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| author | Yong Zhang <yong.zhang0@gmail.com> | 2011-11-09 16:07:14 +0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-11-14 13:54:11 +0100 |
| commit | 87cdee71166fa107c5dc8e43060eeefa533c6a3b (patch) | |
| tree | 286a359e9e27e404f047ce2fa73458353a4b6e9e /kernel | |
| parent | 7f80850d3f9fd8fda23a317044aef3a6bafab06b (diff) | |
| download | linux-stable-87cdee71166fa107c5dc8e43060eeefa533c6a3b.tar.gz linux-stable-87cdee71166fa107c5dc8e43060eeefa533c6a3b.tar.bz2 linux-stable-87cdee71166fa107c5dc8e43060eeefa533c6a3b.zip | |
lockdep: Always try to set ->class_cache in register_lock_class() lockdep_init_map()
Commit ["62016250 lockdep: Add improved subclass caching"] tries to
improve performance (expecially to reduce the cost of rq->lock)
when using lockdep, but it fails due to lockdep_init_map() in
which ->class_cache is cleared. The typical caller is
lock_set_subclass(), after that class will not be cached anymore.
This patch tries to achive the goal of commit 62016250 by always
setting ->class_cache in register_lock_class().
=== Score comparison of benchmarks ===
for i in `seq 1 10`; do ./perf bench -f simple sched messaging; done
before: min: 0.604, max: 0.660, avg: 0.622
after: min: 0.414, max: 0.473, avg: 0.427
for i in `seq 1 10`; do ./perf bench -f simple sched messaging -g 40; done
before: min: 2.347, max: 2.421, avg: 2.391
after: min: 1.652, max: 1.699, avg: 1.671
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20111109080714.GC8124@zhy
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/lockdep.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/lockdep.c b/kernel/lockdep.c index e69434b070da..103bed8423ff 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -722,7 +722,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force) class = look_up_lock_class(lock, subclass); if (likely(class)) - return class; + goto out_set_class_cache; /* * Debug-check: all keys must be persistent! @@ -807,6 +807,7 @@ out_unlock_set: graph_unlock(); raw_local_irq_restore(flags); +out_set_class_cache: if (!subclass || force) lock->class_cache[0] = class; else if (subclass < NR_LOCKDEP_CACHING_CLASSES) |