lkml.org 
[lkml]   [2008]   [Nov]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/5] x86: ret_from_fork - get rid of jump back
[Ingo Molnar - Thu, Nov 27, 2008 at 02:41:21PM +0100]
|
| * Cyrill Gorcunov <gorcunov@gmail.com> wrote:
|
...
|
| Could you test something like the patch attached below, which cleans
| up this code and applies the code reduction and speedup? Warning:
| completely untested! Please check that things like strace -f and gdb
| attaching to forked tasks still works fine. (it should by all means)
|
| Thanks,
|
| Ingo

Ingo, I found 2.6.26 test machine where I've patched the entry_64.S
in a manner you pointed. So here is a test program and strace output.
Seems all works fine. Didn't check "audit" code which I simply don't
know how to be done.

- Cyrill -
---
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
int pid;
pid = fork();

if (pid < 0) {
fprintf(stderr, "Fork failed!\n");
exit(-1);
}
else if (pid == 0) {
printf("I am the child, return from fork=%d\n", pid);
} else {
printf("I am the parent, return from fork, child pid=%d\n", pid);
printf("Parent exiting!\n");
exit(0);
}
}
---
5897 execve("./main", ["./main"], [/* 18 vars */]) = 0
5897 brk(0) = 0x2514000
5897 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fa0e517f000
5897 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
5897 mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fa0e517d000
5897 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
5897 open("/etc/ld.so.cache", O_RDONLY) = 3
5897 fstat(3, {st_mode=S_IFREG|0644, st_size=48530, ...}) = 0
5897 mmap(NULL, 48530, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fa0e5171000
5897 close(3) = 0
5897 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
5897 open("/lib/libc.so.6", O_RDONLY) = 3
5897 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\220\345"..., 832) = 832
5897 fstat(3, {st_mode=S_IFREG|0755, st_size=1502520, ...}) = 0
5897 mmap(NULL, 3609304, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fa0e4bf0000
5897 mprotect(0x7fa0e4d59000, 2093056, PROT_NONE) = 0
5897 mmap(0x7fa0e4f58000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x168000) = 0x7fa0e4f58000
5897 mmap(0x7fa0e4f5d000, 17112, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fa0e4f5d000
5897 close(3) = 0
5897 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fa0e5170000
5897 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fa0e516f000
5897 arch_prctl(ARCH_SET_FS, 0x7fa0e516f6e0) = 0
5897 mprotect(0x7fa0e4f58000, 16384, PROT_READ) = 0
5897 mprotect(0x7fa0e5180000, 4096, PROT_READ) = 0
5897 munmap(0x7fa0e5171000, 48530) = 0
5897 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7fa0e516f770) = 5898
5897 fstat(1, {st_mode=S_IFCHR|0600, st_rdev=makedev(5, 1), ...}) = 0
5898 fstat(1, <unfinished ...>
5897 ioctl(1, SNDCTL_TMR_TIMEBASE or TCGETS <unfinished ...>
5898 <... fstat resumed> {st_mode=S_IFCHR|0600, st_rdev=makedev(5, 1), ...}) = 0
5897 <... ioctl resumed> , {B38400 opost isig icanon echo ...}) = 0
5897 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0 <unfinished ...>
5898 ioctl(1, SNDCTL_TMR_TIMEBASE or TCGETS <unfinished ...>
5897 <... mmap resumed> ) = 0x7fa0e517c000
5898 <... ioctl resumed> , {B38400 opost isig icanon echo ...}) = 0
5897 write(1, "I am the parent, return from for"..., 50 <unfinished ...>
5898 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0 <unfinished ...>
5897 <... write resumed> ) = 50
5898 <... mmap resumed> ) = 0x7fa0e517c000
5897 write(1, "Parent exiting!\n", 16 <unfinished ...>
5898 write(1, "I am the child, return from fork"..., 35 <unfinished ...>
5897 <... write resumed> ) = 16
5898 <... write resumed> ) = 35
5897 exit_group(0) = ?
5898 exit_group(0) = ?
---

\
 
 \ /
  Last update: 2008-11-27 20:15    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site