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| author | Amitay Isaacs <amitay@gmail.com> | 2013-11-19 15:31:39 +1100 |
|---|---|---|
| committer | Michael Adam <obnox@samba.org> | 2013-11-27 18:46:16 +0100 |
| commit | 4ea721b2c16597432dcf517170f7859c713d063e (patch) | |
| tree | 5f7b339b6a36b730591b2a5d35b943d6c548feac /ctdb | |
| parent | d21919c8b4abb5151bdac67c373eb5e85f6a84b4 (diff) | |
| download | samba-4ea721b2c16597432dcf517170f7859c713d063e.tar.gz samba-4ea721b2c16597432dcf517170f7859c713d063e.tar.xz samba-4ea721b2c16597432dcf517170f7859c713d063e.zip | |
ctdb-locking: Use vfork instead of fork to exec helpers
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>
Diffstat (limited to 'ctdb')
| -rw-r--r-- | ctdb/server/ctdb_lock.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/ctdb/server/ctdb_lock.c b/ctdb/server/ctdb_lock.c index 4f9e19bd28e..b71fac28f19 100644 --- a/ctdb/server/ctdb_lock.c +++ b/ctdb/server/ctdb_lock.c @@ -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); |