diff options
| author | Tejun Heo <tj@kernel.org> | 2015-05-13 16:35:17 -0400 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2015-05-26 20:35:00 -0400 |
| commit | d59cfc09c32a2ae31f1c3bc2983a0cd79afb3f14 (patch) | |
| tree | 077533cef8f5e16c8f7fd65d7e255d75828f3820 /kernel/fork.c | |
| parent | 7d7efec368d537226142cbe559f45797f18672f9 (diff) | |
sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem
The cgroup side of threadgroup locking uses signal_struct->group_rwsem
to synchronize against threadgroup changes. This per-process rwsem
adds small overhead to thread creation, exit and exec paths, forces
cgroup code paths to do lock-verify-unlock-retry dance in a couple
places and makes it impossible to atomically perform operations across
multiple processes.
This patch replaces signal_struct->group_rwsem with a global
percpu_rwsem cgroup_threadgroup_rwsem which is cheaper on the reader
side and contained in cgroups proper. This patch converts one-to-one.
This does make writer side heavier and lower the granularity; however,
cgroup process migration is a fairly cold path, we do want to optimize
thread operations over it and cgroup migration operations don't take
enough time for the lower granularity to matter.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 03c1eaaa6ef5..9531275e12a9 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1144,10 +1144,6 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) tty_audit_fork(sig); sched_autogroup_fork(sig); -#ifdef CONFIG_CGROUPS - init_rwsem(&sig->group_rwsem); -#endif - sig->oom_score_adj = current->signal->oom_score_adj; sig->oom_score_adj_min = current->signal->oom_score_adj_min; |