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author | Tejun Heo <tj@kernel.org> | 2015-05-13 23:35:17 +0300 |
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committer | Tejun Heo <tj@kernel.org> | 2015-05-27 03:35:00 +0300 |
commit | d59cfc09c32a2ae31f1c3bc2983a0cd79afb3f14 (patch) | |
tree | 077533cef8f5e16c8f7fd65d7e255d75828f3820 /Makefile | |
parent | 7d7efec368d537226142cbe559f45797f18672f9 (diff) | |
download | linux-d59cfc09c32a2ae31f1c3bc2983a0cd79afb3f14.tar.xz |
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 'Makefile')
0 files changed, 0 insertions, 0 deletions