And let the final binaries get it from that. Fixes building with
-Wl,--as-needed
Signed-off-by: Diego "Flameeyes" Pettenò <flameeyes@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
[acme@filo pahole]$ cat examples/expand_typedefs.c
<SNIP>
typedef struct {
int a, b, c;
} inner;
static struct outer {
int q, b;
inner m;
} foo;
<SNIP>
[acme@filo pahole]$ pahole --expand_types examples/expand_typedefs
/* <158> /home/acme/git/pahole/examples/expand_typedefs.c:7 */
struct outer {
int q; /* 0 4 */
int b; /* 4 4 */
/* typedef inner */ struct {
int a; /* 0 4 */
int b; /* 4 4 */
int c; /* 8 4 */
} m; /* 8 12 */
}; /* size: 20, cachelines: 1 */
/* last cacheline: 20 bytes */
/* definitions: 1 */
[acme@filo pahole]$
For now it does all typedef expansions, which in at least the base types may be
a bit too much, e.g. u32 -> unsigned long int, lets see if somebody complains,
perhaps even myself 8) If that is the case we can add yet another command line
option to specify that such base type expansions should be filtered out, making
the expand_types parameter be flag mask, not just a boolean as it is today.
To see a more complete output look at:
http://oops.ghostprotocols.net:81/acme/dwarves/vmlinux-pahole-expand_types-typedef_unfolding.txt
Suggested by Jeff Muizelaar.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
To tell where to find the elfutils/libdw.h, etc if they are not in the standard
system include dirs, i.e. its no use to find the paths if we don't tell the
cmake system to use the paths found 8)
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
So that we get rid of all the buffer limits, if we need to format into strings
we can use string streams, like we're doing now in just one case, tag__name for
DW_TAG_subroutine_type, that is bogus as it is, as we need to have the name of
the type inside the type declaration (void (*type_name)(parameters)) and not
after (void (*)(parameters) type_name)), but leave this for an upcoming cset.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
1. We now use relayfs
2. ostra-cg is shipped and used in the Makefile
3. README.ctracer has all the details
I followed README.ctracer and the result, in my workstation, was this one:
http://oops.ghostprotocols.net:81/acme/dwarves/callgraphs/acme_eating_his_dog_food/6.html
I've started on the 6th page as it is more interesting, having tcp and netlink
callchains, don't be disappointed by some pages having just one level of
nesting, that is just the lack of containers and aliases (to follow tcp_sock,
skb->sk, etc) from the OSTRA days, but it's getting there! :-)
Ah, it is collecting all the base types in the specified struct by doing a
struct "view", i.e. trimming the struct to have just members that are
"reducible" to basic types (int, long, char, signed and unsigned), then
reorganizing it with the code introduced in pahole --reorganize to get it to
the best layout possible, reducing the size of the entry probe points trace
entries.
Updated rpms are available at the usual place:
http://oops.ghostprotocols.net:81/acme/dwarves/rpm/
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
And use it in a new tool, pglobal, that shows global variables and functions.
Signed-off-by: Davi Arnaut <davi@haxent.com.br>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
So that in tools like ctracer we can print to a file, most of the tools just
pass stdout, keeping the previous behaviour.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Will be used in ctracer to create a struct subset with just the types for which
we have "collectors", i.e. functions that reduce complex types to base types
that will be put in the mini-struct, that will be as tightly packed as it can
be.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This cset also does a fixup for cases where the compiler keeps the type
specified by the programmer for a bitfield but uses less space to combine with
the next, non-bitfield member, these cases can be caught using plain pahole and
will appear with this comment:
/* --- cacheline 1 boundary (64 bytes) --- */
int bitfield1:1; /* 64 4 */
int bitfield2:1; /* 64 4 */
/* XXX 14 bits hole, try to pack */
/* Bitfield WARNING: DWARF size=4, real size=2 */
short int d; /* 66 2 */
The fixup is done prior to reorganizing the fields.
Now an example of this code in action:
[acme@filo examples]$ cat swiss_cheese.c
<SNIP>
struct cheese {
char id;
short number;
char name[52];
int a:1;
int b;
int bitfield1:1;
int bitfield2:1;
short d;
short e;
short last:5;
};
<SNIP>
[acme@filo examples]$
Lets look at the layout:
[acme@filo examples]$ pahole swiss_cheese cheese
/* <11b> /home/acme/git/pahole/examples/swiss_cheese.c:3 */
struct cheese {
char id; /* 0 1 */
/* XXX 1 byte hole, try to pack */
short int number; /* 2 2 */
char name[52]; /* 4 52 */
int a:1; /* 56 4 */
/* XXX 31 bits hole, try to pack */
int b; /* 60 4 */
/* --- cacheline 1 boundary (64 bytes) --- */
int bitfield1:1; /* 64 4 */
int bitfield2:1; /* 64 4 */
/* XXX 14 bits hole, try to pack */
/* Bitfield WARNING: DWARF size=4, real size=2 */
short int d; /* 66 2 */
short int e; /* 68 2 */
short int last:5; /* 70 2 */
}; /* size: 72, cachelines: 2 */
/* sum members: 71, holes: 1, sum holes: 1 */
/* bit holes: 2, sum bit holes: 45 bits */
/* bit_padding: 11 bits */
/* last cacheline: 8 bytes */
[acme@filo examples]$
Full of holes, has bit padding and uses more than one 64 bytes cacheline.
Now lets ask pahole to reorganize it:
[acme@filo examples]$ pahole --reorganize --verbose swiss_cheese cheese
/* Demoting bitfield ('a' ... 'a') from 'int' to 'unsigned char' */
/* Demoting bitfield ('bitfield1' ... 'bitfield2') from 'short unsigned int' to 'unsigned char' */
/* Demoting bitfield ('last') from 'short int' to 'unsigned char' */
/* Moving 'bitfield2:1' from after 'bitfield1' to after 'a:1' */
/* Moving 'bitfield1:1' from after 'b' to after 'bitfield2:1' */
/* Moving 'last:5' from after 'e' to after 'bitfield1:1' */
/* Moving bitfield('a' ... 'last') from after 'name' to after 'id' */
/* Moving 'e' from after 'd' to after 'b' */
/* <11b> /home/acme/git/pahole/examples/swiss_cheese.c:3 */
struct cheese {
char id; /* 0 1 */
unsigned char a:1; /* 1 1 */
unsigned char bitfield2:1; /* 1 1 */
unsigned char bitfield1:1; /* 1 1 */
unsigned char last:5; /* 1 1 */
short int number; /* 2 2 */
char name[52]; /* 4 52 */
int b; /* 56 4 */
short int e; /* 60 2 */
short int d; /* 62 2 */
/* --- cacheline 1 boundary (64 bytes) --- */
}; /* size: 64, cachelines: 1 */
/* saved 8 bytes and 1 cacheline! */
[acme@filo examples]$
Instant karma, it gets completely packed, and look ma, no
__attribute__((packed)) :-)
With this struct task_struct in the linux kernel is shrunk by 12 bytes, there
is more 4 bytes to save with another technique that involves not combining
holes, but using the last single hole to fill it with members at the tail of
the struct.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This allows us to save 4 more bytes in struct task_struct, for instance, now we
need to combine whole bitfields with other fields if some bitfield has a size
less than sizeof(void *) and there is a suitable hole.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Using export CFLAGS="-Wall -Wfatal-errors -Wformat=2 -Wsequence-point -Wextra
-Wno-parentheses -g", suggested by Davi Arnault, amazing how cruft piles up
when one is not looking ;)
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Some are just typedefs, others are inside structs and in some cases its
useful to see the statistics for them, so add two new cmd line options:
-a, --anon_include include anonymous classes\
-A, --nested_anon_include include nested (inside other structs) anonymous classes
Commiter note: I've reworked several aspects of the patch, but mostly to
give better names for the new find_first_typedef_of_type function, adding
a clarifying comment and introducing --nested_anon_include so that we
can select just the typedef'ed anonymous structs.
Damn, I had commited just dwarves.c, here is the dwarves.h and pahole.c bits.
Signed-off-by: Davi Arnaut <davi@haxent.com.br>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Some are just typedefs, others are inside structs and in some cases its
useful to see the statistics for them, so add two new cmd line options:
-a, --anon_include include anonymous classes\
-A, --nested_anon_include include nested (inside other structs) anonymous classes
Commiter note: I've reworked several aspects of the patch, but mostly to
give better names for the new find_first_typedef_of_type function, adding
a clarifying comment and introducing --nested_anon_include so that we
can select just the typedef'ed anonymous structs.
Signed-off-by: Davi Arnaut <davi@haxent.com.br>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
So that we don't have to do all the code emission inside ctracer.c, add
a Makefile too that uses the kernel rpm files shipped by your distro to
easily build a module for your workstation, see README.ctracer, that was
updated to describe the steps needed to have ctracer running in your
machine.
Now to polish the relay code.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diego "Flameeyes" Pettenò
Arnaldo Carvalho de Melo
Arnaldo Carvalho de Melo
Davi Arnaut