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| 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 /init | |
| parent | 7d7efec368d537226142cbe559f45797f18672f9 (diff) | |
| download | lwn-d59cfc09c32a2ae31f1c3bc2983a0cd79afb3f14.tar.gz lwn-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 'init')
| -rw-r--r-- | init/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/init/Kconfig b/init/Kconfig index dc24dec60232..b9b824bf8f6b 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -938,6 +938,7 @@ config NUMA_BALANCING_DEFAULT_ENABLED menuconfig CGROUPS bool "Control Group support" select KERNFS + select PERCPU_RWSEM help This option adds support for grouping sets of processes together, for use with process control subsystems such as Cpusets, CFS, memory |