1ad3de988d
Hacking the gdb.threads/attach-many-short-lived-threads.exp test to spawn thousands of threads instead of dozens, I saw GDB having trouble keeping up with threads being spawned too fast, when it tried to stop them all. This was because while gdb is doing that, it updates the thread list to make sure no new thread has sneaked in that might need to be paused. It does this a few times until it sees no-new-threads twice in a row. The thread listing update itself is not that expensive, however, in the Linux backend, updating the threads list calls linux_common_core_of_thread for each LWP to record on which core each LWP was last seen running, which opens/reads/closes a /proc file for each LWP which becomes expensive when you need to do it for thousands of LWPs. perf shows gdb in linux_common_core_of_thread 44% of the time, in the stop_all_threads -> update_thread_list path in this use case. This patch simply makes linux_common_core_of_thread avoid updating the core the thread is bound to if the thread hasn't run since the last time we updated that info. This makes linux_common_core_of_thread disappear into the noise in the perf report. gdb/ChangeLog: 2016-05-24 Pedro Alves <palves@redhat.com> PR gdb/19828 * linux-nat.c (linux_resume_one_lwp_throw): Clear the LWP's core field. (linux_nat_update_thread_list): Don't fetch the core if already known. |
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ld | ||
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ChangeLog | ||
MAINTAINERS | ||
Makefile.def | ||
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README | ||
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compile | ||
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configure | ||
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depcomp | ||
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ylwrap |
README
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.