Update.
* manual/Makefile (chapters): Add resource. * manual/time.texi: Move section on resources to... * manual/resource.texi: ...here. New file. * manual/setjmp.texi: Adjust back reference. Patch by Bryan Henderson <bryanh@giraffe-data.com>.
This commit is contained in:
Ulrich Drepper
parent
171b7cf149
commit
5ce8f2039b
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@ -1,5 +1,12 @@
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2000-04-17 Ulrich Drepper <drepper@redhat.com>
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* manual/Makefile (chapters): Add resource.
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* manual/time.texi: Move section on resources to...
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* manual/resource.texi: ...here. New file.
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* manual/setjmp.texi: Adjust back reference.
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Patch by Bryan Henderson <bryanh@giraffe-data.com>.
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* sysdeps/unix/sysv/aix/lxstat64.c: Uncomment STX_LINK and STX_64
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definition.
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* sysdeps/unix/sysv/aix/lxstat.c: Uncomment STX_LINK definition.
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@ -1,4 +1,4 @@
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# Copyright (C) 1992, 93, 94, 95, 96, 97, 98, 99 Free Software Foundation, Inc.
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# Copyright (C) 1992-1999, 2000 Free Software Foundation, Inc.
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# This file is part of the GNU C Library.
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# The GNU C Library is free software; you can redistribute it and/or
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@ -54,9 +54,9 @@ mkinstalldirs = $(..)scripts/mkinstalldirs
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chapters = $(addsuffix .texi, \
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intro errno memory ctype string charset locale \
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message search pattern io stdio llio filesys \
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pipe socket terminal math arith time setjmp \
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signal startup process job nss users sysinfo conf\
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crypt)
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pipe socket terminal math arith time resource \
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setjmp signal startup process job nss users \
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sysinfo conf crypt)
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add-chapters = $(wildcard $(foreach d, $(add-ons), ../$d/$d.texi))
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appendices = lang.texi header.texi install.texi maint.texi contrib.texi
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@ -0,0 +1,644 @@
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@node Resource Usage And Limitation, Non-Local Exits, Date and Time, Top
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@c %MENU% Functions for examining resource usage and getting and setting limits
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@chapter Resource Usage And Limitation
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This chapter describes functions for examining how much of various kinds of
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resources (CPU time, memory, etc.) a process has used and getting and setting
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limits on future usage.
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@menu
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* Resource Usage:: Measuring various resources used.
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* Limits on Resources:: Specifying limits on resource usage.
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* Priority:: Reading or setting process run priority.
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@end menu
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@node Resource Usage
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@section Resource Usage
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@pindex sys/resource.h
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The function @code{getrusage} and the data type @code{struct rusage}
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are used to examine the resource usage of a process. They are declared
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in @file{sys/resource.h}.
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@comment sys/resource.h
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@comment BSD
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@deftypefun int getrusage (int @var{processes}, struct rusage *@var{rusage})
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This function reports resource usage totals for processes specified by
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@var{processes}, storing the information in @code{*@var{rusage}}.
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In most systems, @var{processes} has only two valid values:
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@table @code
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@comment sys/resource.h
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@comment BSD
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@item RUSAGE_SELF
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Just the current process.
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@comment sys/resource.h
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@comment BSD
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@item RUSAGE_CHILDREN
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All child processes (direct and indirect) that have already terminated.
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@end table
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In the GNU system, you can also inquire about a particular child process
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by specifying its process ID.
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The return value of @code{getrusage} is zero for success, and @code{-1}
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for failure.
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@table @code
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@item EINVAL
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The argument @var{processes} is not valid.
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@end table
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@end deftypefun
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One way of getting resource usage for a particular child process is with
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the function @code{wait4}, which returns totals for a child when it
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terminates. @xref{BSD Wait Functions}.
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@comment sys/resource.h
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@comment BSD
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@deftp {Data Type} {struct rusage}
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This data type stores various resource usage statistics. It has the
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following members, and possibly others:
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@table @code
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@item struct timeval ru_utime
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Time spent executing user instructions.
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@item struct timeval ru_stime
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Time spent in operating system code on behalf of @var{processes}.
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@item long int ru_maxrss
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The maximum resident set size used, in kilobytes. That is, the maximum
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number of kilobytes of physical memory that @var{processes} used
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simultaneously.
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@item long int ru_ixrss
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An integral value expressed in kilobytes times ticks of execution, which
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indicates the amount of memory used by text that was shared with other
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processes.
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@item long int ru_idrss
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An integral value expressed the same way, which is the amount of
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unshared memory used for data.
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@item long int ru_isrss
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An integral value expressed the same way, which is the amount of
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unshared memory used for stack space.
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@item long int ru_minflt
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The number of page faults which were serviced without requiring any I/O.
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@item long int ru_majflt
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The number of page faults which were serviced by doing I/O.
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@item long int ru_nswap
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The number of times @var{processes} was swapped entirely out of main memory.
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@item long int ru_inblock
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The number of times the file system had to read from the disk on behalf
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of @var{processes}.
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@item long int ru_oublock
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The number of times the file system had to write to the disk on behalf
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of @var{processes}.
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@item long int ru_msgsnd
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Number of IPC messages sent.
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@item long int ru_msgrcv
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Number of IPC messages received.
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@item long int ru_nsignals
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Number of signals received.
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@item long int ru_nvcsw
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The number of times @var{processes} voluntarily invoked a context switch
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(usually to wait for some service).
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@item long int ru_nivcsw
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The number of times an involuntary context switch took place (because
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a time slice expired, or another process of higher priority was
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scheduled).
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@end table
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@end deftp
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@code{vtimes} is a historical function that does some of what
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@code{getrusage} does. @code{getrusage} is a better choice.
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@code{vtimes} and its @code{vtimes} data structure are declared in
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@file{sys/vtimes.h}.
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@pindex sys/vtimes.h
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@comment vtimes.h
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@deftypefun int vtimes (struct vtimes @var{current}, struct vtimes @var{child})
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@code{vtimes} reports resource usage totals for a process.
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If @var{current} is non-null, @code{vtimes} stores resource usage totals for
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the invoking process alone in the structure to which it points. If
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@var{child} is non-null, @code{vtimes} stores resource usage totals for all
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past children (which have terminated) of the invoking process in the structure
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to which it points.
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@deftp {Data Type} {struct vtimes}
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This data type contains information about the resource usage of a process.
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Each member corresponds to a member of the @code{struct rusage} data type
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described above.
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@table @code
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@item vm_utime
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User CPU time. Analogous to @code{ru_utime} in @code{struct rusage}
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@item vm_stime
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System CPU time. Analogous to @code{ru_stime} in @code{struct rusage}
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@item vm_idsrss
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Data and stack memory. The sum of the values that would be reported as
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@code{ru_idrss} and @code{ru_isrss} in @code{struct rusage}
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@item vm_ixrss
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Shared memory. Analogous to @code{ru_ixrss} in @code{struct rusage}
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@item vm_maxrss
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Maximent resident set size. Analogous to @code{ru_maxrss} in
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@code{struct rusage}
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@item vm_majflt
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Major page faults. Analogous to @code{ru_majflt} in @code{struct rusage}
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@item vm_minflt
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Minor page faults. Analogous to @code{ru_minflt} in @code{struct rusage}
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@item vm_nswap
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Swap count. Analogous to @code{ru_nswap} in @code{struct rusage}
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@item vm_inblk
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Disk reads. Analogous to @code{ru_inblk} in @code{struct rusage}
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@item vm_oublk
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Disk writes. Analogous to @code{ru_oublk} in @code{struct rusage}
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@end table
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@end deftp
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The return value is zero if the function succeeds; @code{-1} otherwise.
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@end deftypefun
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An additional historical function for examining resource usage,
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@code{vtimes}, is supported but not documented here. It is declared in
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@file{sys/vtimes.h}.
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@node Limits on Resources
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@section Limiting Resource Usage
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@cindex resource limits
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@cindex limits on resource usage
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@cindex usage limits
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You can specify limits for the resource usage of a process. When the
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process tries to exceed a limit, it may get a signal, or the system call
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by which it tried to do so may fail, depending on the resource. Each
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process initially inherits its limit values from its parent, but it can
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subsequently change them.
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There are two per-process limits associated with a resource:
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@cindex limit
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@table @dfn
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@item current limit
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The current limit is the value the system will not allow usage to
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exceed. It is also called the ``soft limit'' because the process being
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limited can generally raise the current limit at will.
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@cindex current limit
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@cindex soft limit
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@item maximum limit
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The maximum limit is the maximum value to which a process is allowed to
|
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set its current limit. It is also called the ``hard limit'' because
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there is no way for a process to get around it. A process may lower
|
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its own maximum limit, but only the superuser may increase a maximum
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limit.
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@cindex maximum limit
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@cindex hard limit
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@end table
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@pindex sys/resource.h
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The symbols for use with @code{getrlimit}, @code{setrlimit},
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@code{getrlimit64}, and @code{seterlimit64} are defined in
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@file{sys/resource.h}.
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@comment sys/resource.h
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@comment BSD
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@deftypefun int getrlimit (int @var{resource}, struct rlimit *@var{rlp})
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Read the current and maximum limits for the resource @var{resource}
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and store them in @code{*@var{rlp}}.
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|
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The return value is @code{0} on success and @code{-1} on failure. The
|
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only possible @code{errno} error condition is @code{EFAULT}.
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|
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When the sources are compiled with @code{_FILE_OFFSET_BITS == 64} on a
|
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32-bit system this function is in fact @code{getrlimit64}. Thus, the
|
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LFS interface transparently replaces the old interface.
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@end deftypefun
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@comment sys/resource.h
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@comment Unix98
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@deftypefun int getrlimit64 (int @var{resource}, struct rlimit64 *@var{rlp})
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This function is similar to @code{getrlimit} but its second parameter is
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a pointer to a variable of type @code{struct rlimit64}, which allows it
|
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to read values which wouldn't fit in the member of a @code{struct
|
||||
rlimit}.
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|
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If the sources are compiled with @code{_FILE_OFFSET_BITS == 64} on a
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||||
32-bit machine, this function is available under the name
|
||||
@code{getrlimit} and so transparently replaces the old interface.
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@end deftypefun
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@comment sys/resource.h
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@comment BSD
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@deftypefun int setrlimit (int @var{resource}, const struct rlimit *@var{rlp})
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Store the current and maximum limits for the resource @var{resource}
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in @code{*@var{rlp}}.
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|
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The return value is @code{0} on success and @code{-1} on failure. The
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following @code{errno} error condition is possible:
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@table @code
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@item EPERM
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@itemize @bullet
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@item
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||||
The process tried to raise a current limit beyond the maximum limit.
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||||
|
||||
@item
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The process tried to raise a maximum limit, but is not superuser.
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@end itemize
|
||||
@end table
|
||||
|
||||
When the sources are compiled with @code{_FILE_OFFSET_BITS == 64} on a
|
||||
32-bit system this function is in fact @code{setrlimit64}. Thus, the
|
||||
LFS interface transparently replaces the old interface.
|
||||
@end deftypefun
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment Unix98
|
||||
@deftypefun int setrlimit64 (int @var{resource}, const struct rlimit64 *@var{rlp})
|
||||
This function is similar to @code{setrlimit} but its second parameter is
|
||||
a pointer to a variable of type @code{struct rlimit64} which allows it
|
||||
to set values which wouldn't fit in the member of a @code{struct
|
||||
rlimit}.
|
||||
|
||||
If the sources are compiled with @code{_FILE_OFFSET_BITS == 64} on a
|
||||
32-bit machine this function is available under the name
|
||||
@code{setrlimit} and so transparently replaces the old interface.
|
||||
@end deftypefun
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@deftp {Data Type} {struct rlimit}
|
||||
This structure is used with @code{getrlimit} to receive limit values,
|
||||
and with @code{setrlimit} to specify limit values for a particular process
|
||||
and resource. It has two fields:
|
||||
|
||||
@table @code
|
||||
@item rlim_t rlim_cur
|
||||
The current limit
|
||||
|
||||
@item rlim_t rlim_max
|
||||
The maximum limit.
|
||||
@end table
|
||||
|
||||
For @code{getrlimit}, the structure is an output; it receives the current
|
||||
values. For @code{setrlimit}, it specifies the new values.
|
||||
@end deftp
|
||||
|
||||
For the LFS functions a similar type is defined in @file{sys/resource.h}.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment Unix98
|
||||
@deftp {Data Type} {struct rlimit64}
|
||||
This structure is analogous to the @code{rlimit} structure above, but
|
||||
its components have wider ranges. It has two fields:
|
||||
|
||||
@table @code
|
||||
@item rlim64_t rlim_cur
|
||||
This is analogous to @code{rlimit.rlim_cur}, but with a different type.
|
||||
|
||||
@item rlim64_t rlim_max
|
||||
This is analogous to @code{rlimit.rlim_max}, but with a different type.
|
||||
@end table
|
||||
|
||||
@end deftp
|
||||
|
||||
Here is a list of resources for which you can specify a limit. Memory
|
||||
and file sizes are measured in bytes.
|
||||
|
||||
@table @code
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_CPU
|
||||
@vindex RLIMIT_CPU
|
||||
The maximum amount of CPU time the process can use. If it runs for
|
||||
longer than this, it gets a signal: @code{SIGXCPU}. The value is
|
||||
measured in seconds. @xref{Operation Error Signals}.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_FSIZE
|
||||
@vindex RLIMIT_FSIZE
|
||||
The maximum size of file the process can create. Trying to write a
|
||||
larger file causes a signal: @code{SIGXFSZ}. @xref{Operation Error
|
||||
Signals}.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_DATA
|
||||
@vindex RLIMIT_DATA
|
||||
The maximum size of data memory for the process. If the process tries
|
||||
to allocate data memory beyond this amount, the allocation function
|
||||
fails.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_STACK
|
||||
@vindex RLIMIT_STACK
|
||||
The maximum stack size for the process. If the process tries to extend
|
||||
its stack past this size, it gets a @code{SIGSEGV} signal.
|
||||
@xref{Program Error Signals}.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_CORE
|
||||
@vindex RLIMIT_CORE
|
||||
The maximum size core file that this process can create. If the process
|
||||
terminates and would dump a core file larger than this, then no core
|
||||
file is created. So setting this limit to zero prevents core files from
|
||||
ever being created.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_RSS
|
||||
@vindex RLIMIT_RSS
|
||||
The maximum amount of physical memory that this process should get.
|
||||
This parameter is a guide for the system's scheduler and memory
|
||||
allocator; the system may give the process more memory when there is a
|
||||
surplus.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_MEMLOCK
|
||||
The maximum amount of memory that can be locked into physical memory (so
|
||||
it will never be paged out).
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_NPROC
|
||||
The maximum number of processes that can be created with the same user ID.
|
||||
If you have reached the limit for your user ID, @code{fork} will fail
|
||||
with @code{EAGAIN}. @xref{Creating a Process}.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_NOFILE
|
||||
@vindex RLIMIT_NOFILE
|
||||
@itemx RLIMIT_OFILE
|
||||
@vindex RLIMIT_OFILE
|
||||
The maximum number of files that the process can open. If it tries to
|
||||
open more files than this, its open attempt fails with @code{errno}
|
||||
@code{EMFILE}. @xref{Error Codes}. Not all systems support this limit;
|
||||
GNU does, and 4.4 BSD does.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment Unix98
|
||||
@item RLIMIT_AS
|
||||
@vindex RLIMIT_AS
|
||||
The maximum size of total memory that this process should get. If the
|
||||
process tries to allocate more memory beyond this amount with, for
|
||||
example, @code{brk}, @code{malloc}, @code{mmap} or @code{sbrk}, the
|
||||
allocation function fails.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIM_NLIMITS
|
||||
@vindex RLIM_NLIMITS
|
||||
The number of different resource limits. Any valid @var{resource}
|
||||
operand must be less than @code{RLIM_NLIMITS}.
|
||||
@end table
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@deftypevr Constant int RLIM_INFINITY
|
||||
This constant stands for a value of ``infinity'' when supplied as
|
||||
the limit value in @code{setrlimit}.
|
||||
@end deftypevr
|
||||
|
||||
|
||||
The following are historical functions to do some of what the functions
|
||||
above do. The functions above are better choices.
|
||||
|
||||
@code{ulimit} and the command symbols are declared in @file{ulimit.h}.
|
||||
@pindex ulimit.h
|
||||
@comment ulimit.h
|
||||
|
||||
@deftypefun int ulimit (int @var{cmd}, ...)
|
||||
|
||||
@code{ulimit} gets the current limit or sets the current and maximum
|
||||
limit for a particular resource for the calling process according to the
|
||||
command @var{cmd}.a
|
||||
|
||||
If you are getting a limit, the command argument is the only argument.
|
||||
If you are setting a limit, there is a second argument:
|
||||
@code{long int} @var{limit} which is the value to which you are setting
|
||||
the limit.
|
||||
|
||||
The @var{cmd} values and the operations they specify are:
|
||||
@table @code
|
||||
|
||||
@item GETFSIZE
|
||||
Get the current limit on the size of a file, in units of 512 bytes.
|
||||
|
||||
@item SETFSIZE
|
||||
Set the current and maximum limit on the size of a file to @var{limit} *
|
||||
512 bytes.
|
||||
|
||||
@end table
|
||||
|
||||
There are also some other @var{cmd} values that may do things on some
|
||||
systems, but they are not supported.
|
||||
|
||||
Only the superuser may increase a maximum limit.
|
||||
|
||||
When you successfully get a limit, the return value of @code{ulimit} is
|
||||
that limit, which is never negative. When you successfully set a limit,
|
||||
the return value is zero. When the function fails, the return value is
|
||||
@code{-1} and @code{errno} is set according to the reason:
|
||||
|
||||
@table @code
|
||||
@item EPERM
|
||||
A process tried to increase a maximum limit, but is not superuser.
|
||||
@end table
|
||||
|
||||
|
||||
@end deftypefun
|
||||
|
||||
@code{vlimit} and its resource symbols are declared in @file{sys/vlimit.h}.
|
||||
@comment sys/vlimit.h
|
||||
@pindex sys/vlimit.h
|
||||
@comment BSD
|
||||
|
||||
@deftypefun int vlimit (int @var{resource}, int @var{limit})
|
||||
|
||||
@code{vlimit} sets the current limit for a resource for a process.
|
||||
|
||||
@var{resource} identifies the resource:
|
||||
|
||||
@table @code
|
||||
@item LIM_CPU
|
||||
Maximum CPU time. Same as @code{RLIMIT_CPU} for @code{setrlimit}.
|
||||
@item LIM_FSIZE
|
||||
Maximum file size. Same as @code{RLIMIT_FSIZE} for @code{setrlimit}.
|
||||
@item LIM_DATA
|
||||
Maximum data memory. Same as @code{RLIMIT_DATA} for @code{setrlimit}.
|
||||
@item LIM_STACK
|
||||
Maximum stack size. Same as @code{RLIMIT_STACK} for @code{setrlimit}.
|
||||
@item LIM_CORE
|
||||
Maximum core file size. Same as @code{RLIMIT_COR} for @code{setrlimit}.
|
||||
@item LIM_MAXRSS
|
||||
Maximum physical memory. Same as @code{RLIMIT_RSS} for @code{setrlimit}.
|
||||
@end table
|
||||
|
||||
The return value is zero for success, and @code{-1} with @code{errno} set
|
||||
accordingly for failure:
|
||||
|
||||
@table @code
|
||||
@item EPERM
|
||||
The process tried to set its current limit beyond its maximum limit.
|
||||
@end table
|
||||
|
||||
@end deftypefun
|
||||
|
||||
@node Priority
|
||||
@section Process Priority
|
||||
@cindex process priority
|
||||
@cindex priority of a process
|
||||
|
||||
@pindex sys/resource.h
|
||||
When several processes try to run, their respective priorities determine
|
||||
what share of the CPU each process gets. This section describes how you
|
||||
can read and set the priority of a process. All these functions and
|
||||
macros are declared in @file{sys/resource.h}.
|
||||
|
||||
The range of valid priority values depends on the operating system, but
|
||||
typically it runs from @code{-20} to @code{20}. A lower priority value
|
||||
means the process runs more often. These constants describe the range of
|
||||
priority values:
|
||||
|
||||
@table @code
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item PRIO_MIN
|
||||
@vindex PRIO_MIN
|
||||
The smallest valid priority value.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item PRIO_MAX
|
||||
@vindex PRIO_MAX
|
||||
The largest valid priority value.
|
||||
@end table
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@deftypefun int getpriority (int @var{class}, int @var{id})
|
||||
Read the priority of a class of processes; @var{class} and @var{id}
|
||||
specify which ones (see below). If the processes specified do not all
|
||||
have the same priority, this returns the smallest value that any of them
|
||||
has.
|
||||
|
||||
The return value is the priority value on success, and @code{-1} on
|
||||
failure. The following @code{errno} error condition are possible for
|
||||
this function:
|
||||
|
||||
@table @code
|
||||
@item ESRCH
|
||||
The combination of @var{class} and @var{id} does not match any existing
|
||||
process.
|
||||
|
||||
@item EINVAL
|
||||
The value of @var{class} is not valid.
|
||||
@end table
|
||||
|
||||
If the return value is @code{-1}, it could indicate failure, or it
|
||||
could be the priority value. The only way to make certain is to set
|
||||
@code{errno = 0} before calling @code{getpriority}, then use @code{errno
|
||||
!= 0} afterward as the criterion for failure.
|
||||
@end deftypefun
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@deftypefun int setpriority (int @var{class}, int @var{id}, int @var{priority})
|
||||
Set the priority of a class of processes to @var{priority}; @var{class}
|
||||
and @var{id} specify which ones (see below).
|
||||
|
||||
The return value is @code{0} on success and @code{-1} on failure. The
|
||||
following @code{errno} error condition are defined for this function:
|
||||
|
||||
@table @code
|
||||
@item ESRCH
|
||||
The combination of @var{class} and @var{id} does not match any existing
|
||||
process.
|
||||
|
||||
@item EINVAL
|
||||
The value of @var{class} is not valid.
|
||||
|
||||
@item EPERM
|
||||
You tried to set the priority of some other user's process, and you
|
||||
don't have privileges for that.
|
||||
|
||||
@item EACCES
|
||||
You tried to lower the priority of a process, and you don't have
|
||||
privileges for that.
|
||||
@end table
|
||||
@end deftypefun
|
||||
|
||||
The arguments @var{class} and @var{id} together specify a set of
|
||||
processes in which you are interested. These are the possible values of
|
||||
@var{class}:
|
||||
|
||||
@table @code
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item PRIO_PROCESS
|
||||
@vindex PRIO_PROCESS
|
||||
Read or set the priority of one process. The argument @var{id} is a
|
||||
process ID.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item PRIO_PGRP
|
||||
@vindex PRIO_PGRP
|
||||
Read or set the priority of one process group. The argument @var{id} is
|
||||
a process group ID.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item PRIO_USER
|
||||
@vindex PRIO_USER
|
||||
Read or set the priority of one user's processes. The argument @var{id}
|
||||
is a user ID.
|
||||
@end table
|
||||
|
||||
If the argument @var{id} is 0, it stands for the current process,
|
||||
current process group, or the current user, according to @var{class}.
|
||||
|
||||
@c ??? I don't know where we should say this comes from.
|
||||
@comment Unix
|
||||
@comment dunno.h
|
||||
@deftypefun int nice (int @var{increment})
|
||||
Increment the priority of the current process by @var{increment}.
|
||||
The return value is the same as for @code{setpriority}.
|
||||
|
||||
Here is an equivalent definition of @code{nice}:
|
||||
|
||||
@smallexample
|
||||
int
|
||||
nice (int increment)
|
||||
@{
|
||||
int old = getpriority (PRIO_PROCESS, 0);
|
||||
return setpriority (PRIO_PROCESS, 0, old + increment);
|
||||
@}
|
||||
@end smallexample
|
||||
@end deftypefun
|
||||
|
|
@ -1,4 +1,4 @@
|
|||
@node Non-Local Exits, Signal Handling, Date and Time, Top
|
||||
@node Non-Local Exits, Signal Handling, Resource Usage And Limitation, Top
|
||||
@c %MENU% Jumping out of nested function calls
|
||||
@chapter Non-Local Exits
|
||||
@cindex non-local exits
|
||||
|
|
|
|||
487
manual/time.texi
487
manual/time.texi
|
|
@ -1,4 +1,4 @@
|
|||
@node Date and Time, Non-Local Exits, Arithmetic, Top
|
||||
@node Date and Time, Resource Usage And Limitation, Arithmetic, Top
|
||||
@c %MENU% Functions for getting the date and time and formatting them nicely
|
||||
@chapter Date and Time
|
||||
|
||||
|
|
@ -29,11 +29,12 @@ an Alarm}.
|
|||
time.
|
||||
* Setting an Alarm:: Sending a signal after a specified time.
|
||||
* Sleeping:: Waiting for a period of time.
|
||||
* Resource Usage:: Measuring various resources used.
|
||||
* Limits on Resources:: Specifying limits on resource usage.
|
||||
* Priority:: Reading or setting process run priority.
|
||||
@end menu
|
||||
|
||||
For functions to examine and control a process' CPU time, see
|
||||
@xref{Resource Usage And Limitation}.
|
||||
|
||||
|
||||
@node Processor Time
|
||||
@section Processor Time
|
||||
|
||||
|
|
@ -2263,481 +2264,3 @@ be protected using cancellation handlers.
|
|||
The @code{nanosleep} function is declared in @file{time.h}.
|
||||
@end deftypefun
|
||||
|
||||
@node Resource Usage
|
||||
@section Resource Usage
|
||||
|
||||
@pindex sys/resource.h
|
||||
The function @code{getrusage} and the data type @code{struct rusage} are
|
||||
used to examine the resource usage of a process. They are declared in
|
||||
@file{sys/resource.h}.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@deftypefun int getrusage (int @var{processes}, struct rusage *@var{rusage})
|
||||
This function reports resource usage totals for processes specified by
|
||||
@var{processes}, storing the information in @code{*@var{rusage}}.
|
||||
|
||||
In most systems, @var{processes} has only two valid values:
|
||||
|
||||
@table @code
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RUSAGE_SELF
|
||||
Just the current process.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RUSAGE_CHILDREN
|
||||
All child processes (direct and indirect) that have already terminated.
|
||||
@end table
|
||||
|
||||
In the GNU system, you can also inquire about a particular child process
|
||||
by specifying its process ID.
|
||||
|
||||
The return value of @code{getrusage} is zero for success, and @code{-1}
|
||||
for failure.
|
||||
|
||||
@table @code
|
||||
@item EINVAL
|
||||
The argument @var{processes} is not valid.
|
||||
@end table
|
||||
@end deftypefun
|
||||
|
||||
One way of getting resource usage for a particular child process is with
|
||||
the function @code{wait4}, which returns totals for a child when it
|
||||
terminates. @xref{BSD Wait Functions}.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@deftp {Data Type} {struct rusage}
|
||||
This data type stores various resource usage statistics. It has the
|
||||
following members, and possibly others:
|
||||
|
||||
@table @code
|
||||
@item struct timeval ru_utime
|
||||
Time spent executing user instructions.
|
||||
|
||||
@item struct timeval ru_stime
|
||||
Time spent in operating system code on behalf of @var{processes}.
|
||||
|
||||
@item long int ru_maxrss
|
||||
The maximum resident set size used, in kilobytes. That is, the maximum
|
||||
number of kilobytes of physical memory that @var{processes} used
|
||||
simultaneously.
|
||||
|
||||
@item long int ru_ixrss
|
||||
An integral value expressed in kilobytes times ticks of execution, which
|
||||
indicates the amount of memory used by text that was shared with other
|
||||
processes.
|
||||
|
||||
@item long int ru_idrss
|
||||
An integral value expressed the same way, which is the amount of
|
||||
unshared memory used for data.
|
||||
|
||||
@item long int ru_isrss
|
||||
An integral value expressed the same way, which is the amount of
|
||||
unshared memory used for stack space.
|
||||
|
||||
@item long int ru_minflt
|
||||
The number of page faults which were serviced without requiring any I/O.
|
||||
|
||||
@item long int ru_majflt
|
||||
The number of page faults which were serviced by doing I/O.
|
||||
|
||||
@item long int ru_nswap
|
||||
The number of times @var{processes} was swapped entirely out of main memory.
|
||||
|
||||
@item long int ru_inblock
|
||||
The number of times the file system had to read from the disk on behalf
|
||||
of @var{processes}.
|
||||
|
||||
@item long int ru_oublock
|
||||
The number of times the file system had to write to the disk on behalf
|
||||
of @var{processes}.
|
||||
|
||||
@item long int ru_msgsnd
|
||||
Number of IPC messages sent.
|
||||
|
||||
@item long ru_msgrcv
|
||||
Number of IPC messages received.
|
||||
|
||||
@item long int ru_nsignals
|
||||
Number of signals received.
|
||||
|
||||
@item long int ru_nvcsw
|
||||
The number of times @var{processes} voluntarily invoked a context switch
|
||||
(usually to wait for some service).
|
||||
|
||||
@item long int ru_nivcsw
|
||||
The number of times an involuntary context switch took place (because a
|
||||
time slice expired, or another process of higher priority was
|
||||
scheduled).
|
||||
@end table
|
||||
@end deftp
|
||||
|
||||
An additional historical function for examining resource usage,
|
||||
@code{vtimes}, is supported but not documented here. It is declared in
|
||||
@file{sys/vtimes.h}.
|
||||
|
||||
@node Limits on Resources
|
||||
@section Limiting Resource Usage
|
||||
@cindex resource limits
|
||||
@cindex limits on resource usage
|
||||
@cindex usage limits
|
||||
|
||||
You can specify limits for the resource usage of a process. When the
|
||||
process tries to exceed a given limit, it may get a signal, or the system call
|
||||
by which it tried to do so may fail, depending on the limit in question. Each
|
||||
process initially inherits its limit values from its parent, but it can
|
||||
subsequently change them.
|
||||
|
||||
@pindex sys/resource.h
|
||||
The symbols in this section are defined in @file{sys/resource.h}.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@deftypefun int getrlimit (int @var{resource}, struct rlimit *@var{rlp})
|
||||
Read the current value and the maximum value of resource @var{resource}
|
||||
and store them in @code{*@var{rlp}}.
|
||||
|
||||
The return value is @code{0} on success and @code{-1} on failure. The
|
||||
only possible @code{errno} error condition is @code{EFAULT}.
|
||||
|
||||
When the sources are compiled with @code{_FILE_OFFSET_BITS == 64} on a
|
||||
32-bit system, this function is in fact @code{getrlimit64}. Thus the
|
||||
LFS interface transparently replaces the old interface.
|
||||
@end deftypefun
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment Unix98
|
||||
@deftypefun int getrlimit64 (int @var{resource}, struct rlimit64 *@var{rlp})
|
||||
This function is similar to @code{getrlimit}, but its second
|
||||
parameter is a pointer to a variable of type @code{struct rlimit64},
|
||||
allowing it to read values which wouldn't fit in the member
|
||||
of a @code{struct rlimit}.
|
||||
|
||||
If the sources are compiled with @code{_FILE_OFFSET_BITS == 64} on a
|
||||
32-bit machine, this function is available under the name
|
||||
@code{getrlimit} and so transparently replaces the old interface.
|
||||
@end deftypefun
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@deftypefun int setrlimit (int @var{resource}, const struct rlimit *@var{rlp})
|
||||
Store the current value and the maximum value of resource @var{resource}
|
||||
in @code{*@var{rlp}}.
|
||||
|
||||
The return value is @code{0} on success and @code{-1} on failure. The
|
||||
following @code{errno} error condition is possible:
|
||||
|
||||
@table @code
|
||||
@item EPERM
|
||||
You tried to change the maximum permissible limit value,
|
||||
but you don't have privileges to do so.
|
||||
@end table
|
||||
|
||||
When the sources are compiled with @code{_FILE_OFFSET_BITS == 64} on a
|
||||
32-bit system this function is in fact @code{setrlimit64}. Thus the
|
||||
LFS interface transparently replaces the old interface.
|
||||
@end deftypefun
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment Unix98
|
||||
@deftypefun int setrlimit64 (int @var{resource}, const struct rlimit64 *@var{rlp})
|
||||
This function is similar to @code{setrlimit}, but its second parameter
|
||||
is a pointer to a variable of type @code{struct rlimit64}, allowing it
|
||||
to set values which wouldn't fit in the member of a @code{struct
|
||||
rlimit}.
|
||||
|
||||
If the sources are compiled with @code{_FILE_OFFSET_BITS == 64} on a
|
||||
32-bit machine, this function is available under the name
|
||||
@code{setrlimit} and so transparently replaces the old interface.
|
||||
@end deftypefun
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@deftp {Data Type} {struct rlimit}
|
||||
This structure is used with @code{getrlimit} to receive limit values,
|
||||
and with @code{setrlimit} to specify limit values. It has two fields:
|
||||
|
||||
@table @code
|
||||
@item rlim_t rlim_cur
|
||||
The current value of the limit in question.
|
||||
This is also called the ``soft limit''.
|
||||
@cindex soft limit
|
||||
|
||||
@item rlim_t rlim_max
|
||||
The maximum permissible value of the limit in question. You cannot set
|
||||
the current value of the limit to a larger number than this maximum.
|
||||
Only the super-user can change the maximum permissible value.
|
||||
This is also called the ``hard limit''.
|
||||
@cindex hard limit
|
||||
@end table
|
||||
|
||||
For @code{getrlimit}, the structure is an output; it receives the current
|
||||
value. With @code{setrlimit} it specifies the new value.
|
||||
@end deftp
|
||||
|
||||
For the LFS functions a similar type is defined in @file{sys/resource.h}.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment Unix98
|
||||
@deftp {Data Type} {struct rlimit64}
|
||||
This structure is used with @code{getrlimit64} to receive limit values,
|
||||
and with @code{setrlimit64} to specify limit values. It has two fields:
|
||||
|
||||
@table @code
|
||||
@item rlim64_t rlim_cur
|
||||
The current value of the limit in question.
|
||||
This is also called the ``soft limit''.
|
||||
|
||||
@item rlim64_t rlim_max
|
||||
The maximum permissible value of the limit in question. You cannot set
|
||||
the current value of the limit to a larger number than this maximum.
|
||||
Only the super-user can change the maximum permissible value.
|
||||
This is also called the ``hard limit''.
|
||||
@end table
|
||||
|
||||
For @code{getrlimit64}, the structure is an output; it receives the current
|
||||
value. With @code{setrlimit64} it specifies the new value.
|
||||
@end deftp
|
||||
|
||||
Here is a list of resources that you can specify a limit for.
|
||||
Memory sizes are measured in bytes.
|
||||
|
||||
@table @code
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_CPU
|
||||
@vindex RLIMIT_CPU
|
||||
The maximum amount of CPU time the process can use. If it runs for
|
||||
longer than this, it gets a signal: @code{SIGXCPU}. The value is
|
||||
measured in seconds. @xref{Operation Error Signals}.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_FSIZE
|
||||
@vindex RLIMIT_FSIZE
|
||||
The maximum size of file the process can create. Trying to write a
|
||||
larger file causes a signal: @code{SIGXFSZ}. @xref{Operation Error
|
||||
Signals}.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_DATA
|
||||
@vindex RLIMIT_DATA
|
||||
The maximum size of data memory for the process. If the process tries
|
||||
to allocate data memory beyond this amount, the allocation function
|
||||
fails.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_STACK
|
||||
@vindex RLIMIT_STACK
|
||||
The maximum stack size for the process. If the process tries to extend
|
||||
its stack past this size, it gets a @code{SIGSEGV} signal.
|
||||
@xref{Program Error Signals}.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_CORE
|
||||
@vindex RLIMIT_CORE
|
||||
The maximum size core file that this process can create. If the process
|
||||
terminates and would dump a core file larger than this,
|
||||
then no core file is created. So setting this limit to zero prevents
|
||||
core files from ever being created.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_RSS
|
||||
@vindex RLIMIT_RSS
|
||||
The maximum amount of physical memory that this process should get.
|
||||
This parameter is a guide for the system's scheduler and memory
|
||||
allocator; the system may give the process more memory when there is a
|
||||
surplus.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_MEMLOCK
|
||||
The maximum amount of memory that can be locked into physical memory (so
|
||||
it will never be paged out).
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_NPROC
|
||||
The maximum number of processes that can be created with the same user ID.
|
||||
If you have reached the limit for your user ID, @code{fork} will fail
|
||||
with @code{EAGAIN}. @xref{Creating a Process}.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIMIT_NOFILE
|
||||
@vindex RLIMIT_NOFILE
|
||||
@itemx RLIMIT_OFILE
|
||||
@vindex RLIMIT_OFILE
|
||||
The maximum number of files that the process can open. If it tries to
|
||||
open more files than this, it gets the error code @code{EMFILE}.
|
||||
@xref{Error Codes}. Not all systems support this limit; GNU does, and
|
||||
4.4 BSD does.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment Unix98
|
||||
@item RLIMIT_AS
|
||||
@vindex RLIMIT_AS
|
||||
The maximum size of total memory that this process should get. If the
|
||||
process tries to allocate more memory beyond this amount with, for
|
||||
example, @code{brk}, @code{malloc}, @code{mmap} or @code{sbrk}, the
|
||||
allocation function fails.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item RLIM_NLIMITS
|
||||
@vindex RLIM_NLIMITS
|
||||
The number of different resource limits. Any valid @var{resource}
|
||||
operand must be less than @code{RLIM_NLIMITS}.
|
||||
@end table
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@deftypevr Constant int RLIM_INFINITY
|
||||
This constant stands for a value of ``infinity'' when supplied as
|
||||
the limit value in @code{setrlimit}.
|
||||
@end deftypevr
|
||||
|
||||
@c ??? Someone want to finish these?
|
||||
Two historical functions for setting resource limits, @code{ulimit} and
|
||||
@code{vlimit}, are not documented here. The latter is declared in
|
||||
@file{sys/vlimit.h} and comes from BSD.
|
||||
|
||||
@node Priority
|
||||
@section Process Priority
|
||||
@cindex process priority
|
||||
@cindex priority of a process
|
||||
|
||||
@pindex sys/resource.h
|
||||
When several processes try to run, their respective priorities determine
|
||||
what share of the CPU each process gets. This section describes how you
|
||||
can read and set the priority of a process. All these functions and
|
||||
macros are declared in @file{sys/resource.h}.
|
||||
|
||||
The range of valid priority values depends on the operating system, but
|
||||
typically it runs from @code{-20} to @code{20}. A lower priority value
|
||||
means the process runs more often. These constants describe the range of
|
||||
priority values:
|
||||
|
||||
@table @code
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item PRIO_MIN
|
||||
@vindex PRIO_MIN
|
||||
The smallest valid priority value.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item PRIO_MAX
|
||||
@vindex PRIO_MAX
|
||||
The largest valid priority value.
|
||||
@end table
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@deftypefun int getpriority (int @var{class}, int @var{id})
|
||||
Read the priority of a class of processes; @var{class} and @var{id}
|
||||
specify which ones (see below). If the processes specified do not all
|
||||
have the same priority, this returns the smallest value that any of them
|
||||
has.
|
||||
|
||||
The return value is the priority value on success, and @code{-1} on
|
||||
failure. The following @code{errno} error condition are possible for
|
||||
this function:
|
||||
|
||||
@table @code
|
||||
@item ESRCH
|
||||
The combination of @var{class} and @var{id} does not match any existing
|
||||
process.
|
||||
|
||||
@item EINVAL
|
||||
The value of @var{class} is not valid.
|
||||
@end table
|
||||
|
||||
If the return value is @code{-1}, it could indicate failure, or it
|
||||
could be the priority value. The only way to make certain is to set
|
||||
@code{errno = 0} before calling @code{getpriority}, then use @code{errno
|
||||
!= 0} afterward as the criterion for failure.
|
||||
@end deftypefun
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@deftypefun int setpriority (int @var{class}, int @var{id}, int @var{priority})
|
||||
Set the priority of a class of processes to @var{priority}; @var{class}
|
||||
and @var{id} specify which ones (see below).
|
||||
|
||||
The return value is @code{0} on success and @code{-1} on failure. The
|
||||
following @code{errno} error condition are defined for this function:
|
||||
|
||||
@table @code
|
||||
@item ESRCH
|
||||
The combination of @var{class} and @var{id} does not match any existing
|
||||
process.
|
||||
|
||||
@item EINVAL
|
||||
The value of @var{class} is not valid.
|
||||
|
||||
@item EPERM
|
||||
You tried to set the priority of some other user's process, and you
|
||||
don't have privileges for that.
|
||||
|
||||
@item EACCES
|
||||
You tried to lower the priority of a process, and you don't have
|
||||
privileges for that.
|
||||
@end table
|
||||
@end deftypefun
|
||||
|
||||
The arguments @var{class} and @var{id} together specify a set of
|
||||
processes you are interested in. These are the possible values of
|
||||
@var{class}:
|
||||
|
||||
@table @code
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item PRIO_PROCESS
|
||||
@vindex PRIO_PROCESS
|
||||
Read or set the priority of one process. The argument @var{id} is a
|
||||
process ID.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item PRIO_PGRP
|
||||
@vindex PRIO_PGRP
|
||||
Read or set the priority of one process group. The argument @var{id} is
|
||||
a process group ID.
|
||||
|
||||
@comment sys/resource.h
|
||||
@comment BSD
|
||||
@item PRIO_USER
|
||||
@vindex PRIO_USER
|
||||
Read or set the priority of one user's processes. The argument @var{id}
|
||||
is a user ID.
|
||||
@end table
|
||||
|
||||
If the argument @var{id} is 0, it stands for the current process,
|
||||
current process group, or the current user, according to @var{class}.
|
||||
|
||||
@c ??? I don't know where we should say this comes from.
|
||||
@comment Unix
|
||||
@comment dunno.h
|
||||
@deftypefun int nice (int @var{increment})
|
||||
Increment the priority of the current process by @var{increment}.
|
||||
The return value is the same as for @code{setpriority}.
|
||||
|
||||
Here is an equivalent definition of @code{nice}:
|
||||
|
||||
@smallexample
|
||||
int
|
||||
nice (int increment)
|
||||
@{
|
||||
int old = getpriority (PRIO_PROCESS, 0);
|
||||
return setpriority (PRIO_PROCESS, 0, old + increment);
|
||||
@}
|
||||
@end smallexample
|
||||
@end deftypefun
|
||||
|
|
|
|||
Loading…
Reference in New Issue