diff options
| author | Tejun Heo | 2015-05-13 22:35:17 +0200 |
|---|---|---|
| committer | Tejun Heo | 2015-05-27 02:35:00 +0200 |
| commit | d59cfc09c32a2ae31f1c3bc2983a0cd79afb3f14 (patch) | |
| tree | 077533cef8f5e16c8f7fd65d7e255d75828f3820 /include/linux/sched.h | |
| parent | sched, cgroup: reorganize threadgroup locking (diff) | |
| download | kernel-qcow2-linux-d59cfc09c32a2ae31f1c3bc2983a0cd79afb3f14.tar.gz kernel-qcow2-linux-d59cfc09c32a2ae31f1c3bc2983a0cd79afb3f14.tar.xz kernel-qcow2-linux-d59cfc09c32a2ae31f1c3bc2983a0cd79afb3f14.zip | |
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 'include/linux/sched.h')
| -rw-r--r-- | include/linux/sched.h | 12 |
1 files changed, 0 insertions, 12 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 5ee290003470..add524a910bd 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -743,18 +743,6 @@ struct signal_struct { unsigned audit_tty_log_passwd; struct tty_audit_buf *tty_audit_buf; #endif -#ifdef CONFIG_CGROUPS - /* - * group_rwsem prevents new tasks from entering the threadgroup and - * member tasks from exiting,a more specifically, setting of - * PF_EXITING. fork and exit paths are protected with this rwsem - * using threadgroup_change_begin/end(). Users which require - * threadgroup to remain stable should use threadgroup_[un]lock() - * which also takes care of exec path. Currently, cgroup is the - * only user. - */ - struct rw_semaphore group_rwsem; -#endif oom_flags_t oom_flags; short oom_score_adj; /* OOM kill score adjustment */ |