sin/samba-mirror
1
0
Fork 0
mirror of https://github.com/samba-team/samba.git synced 2024-12-22 13:34:15 +03:00
Code

ctdb-locking: Use vfork instead of fork to exec helpers

Browse Source 
There is a significant overhead using fork() over vfork(), specially
when the child process execs a helper.  The overhead is in memory space
and time.

    # strace -c ./test_fork 1024 200
    count=1024, size=204800, total=200M
    failed fork=0
    time for fork() = 4879.597000 us
    % time     seconds  usecs/call     calls    errors syscall
    ------ ----------- ----------- --------- --------- ----------------
    100.00    4.543321        3304      1375       375 clone
      0.00    0.000071           0      1033           mmap
      0.00    0.000000           0         1           read
      0.00    0.000000           0         3           write
      0.00    0.000000           0         2           open
      0.00    0.000000           0         2           close
      0.00    0.000000           0         3           fstat
      0.00    0.000000           0         3           mprotect
      0.00    0.000000           0         1           munmap
      0.00    0.000000           0         3           brk
      0.00    0.000000           0         1         1 access
      0.00    0.000000           0         1           execve
      0.00    0.000000           0         1           arch_prctl
    ------ ----------- ----------- --------- --------- ----------------
    100.00    4.543392                  2429       376 total

    # strace -c ./test_vfork 1024 200
    count=1024, size=204800, total=200M
    failed fork=0
    time for fork() = 82.041000 us
    % time     seconds  usecs/call     calls    errors syscall
    ------ ----------- ----------- --------- --------- ----------------
     96.47    0.001204           1      1000           vfork
      3.53    0.000044           0      1033           mmap
      0.00    0.000000           0         1           read
      0.00    0.000000           0         3           write
      0.00    0.000000           0         2           open
      0.00    0.000000           0         2           close
      0.00    0.000000           0         3           fstat
      0.00    0.000000           0         3           mprotect
      0.00    0.000000           0         1           munmap
      0.00    0.000000           0         3           brk
      0.00    0.000000           0         1         1 access
      0.00    0.000000           0         1           execve
      0.00    0.000000           0         1           arch_prctl
    ------ ----------- ----------- --------- --------- ----------------
    100.00    0.001248                  2054         1 total

Signed-off-by: Amitay Isaacs <amitay@gmail.com>
Reviewed-by: Michael Adam <obnox@samba.org>
This commit is contained in:
Amitay Isaacs 2013-11-19 15:31:39 +11:00 committed by Michael Adam
parent d21919c8b4
commit 4ea721b2c1
1 changed files with 5 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
ctdb/server/ctdb_lock.c
View File

@ -528,10 +528,12 @@ static void ctdb_lock_timeout_handler(struct tevent_context *ev,
}
}
if (debug_locks != NULL) {
pid = fork();
pid = vfork();
if (pid == 0) {
execl(debug_locks, debug_locks, NULL);
_exit(0);
}
ctdb_track_child(ctdb, pid);
} else {
DEBUG(DEBUG_WARNING,
(__location__
@ -810,7 +812,7 @@ static void ctdb_lock_schedule(struct ctdb_context *ctdb)
return;
}
lock_ctx->child = ctdb_fork(ctdb);
lock_ctx->child = vfork();
if (lock_ctx->child == (pid_t)-1) {
DEBUG(DEBUG_ERR, ("Failed to create a child in ctdb_lock_schedule\n"));
@ -832,6 +834,7 @@ static void ctdb_lock_schedule(struct ctdb_context *ctdb)
}
/* Parent process */
ctdb_track_child(ctdb, lock_ctx->child);
close(lock_ctx->fd[1]);
talloc_set_destructor(lock_ctx, ctdb_lock_context_destructor);