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| author | mjg <mjg@FreeBSD.org> | 2016-06-01 18:32:20 +0000 |
|---|---|---|
| committer | mjg <mjg@FreeBSD.org> | 2016-06-01 18:32:20 +0000 |
| commit | 25669dd1d9562b9b1717d5ef59b15e1716c81634 (patch) | |
| tree | fd835dd80fc66ba43f6cdb85dc37e7ec1c12c055 /sys/sys/mutex.h | |
| parent | 1a924c729cc82916157766dbb0389b73fd4a79d8 (diff) | |
| download | FreeBSD-src-25669dd1d9562b9b1717d5ef59b15e1716c81634.zip FreeBSD-src-25669dd1d9562b9b1717d5ef59b15e1716c81634.tar.gz | |
Microoptimize locking primitives by avoiding unnecessary atomic ops.
Inline version of primitives do an atomic op and if it fails they fallback to
actual primitives, which immediately retry the atomic op.
The obvious optimisation is to check if the lock is free and only then proceed
to do an atomic op.
Reviewed by: jhb, vangyzen
Diffstat (limited to 'sys/sys/mutex.h')
| -rw-r--r-- | sys/sys/mutex.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/sys/sys/mutex.h b/sys/sys/mutex.h index a9ec072..0443922 100644 --- a/sys/sys/mutex.h +++ b/sys/sys/mutex.h @@ -185,7 +185,7 @@ void thread_lock_flags_(struct thread *, int, const char *, int); #define __mtx_lock(mp, tid, opts, file, line) do { \ uintptr_t _tid = (uintptr_t)(tid); \ \ - if (!_mtx_obtain_lock((mp), _tid)) \ + if (((mp)->mtx_lock != MTX_UNOWNED || !_mtx_obtain_lock((mp), _tid)))\ _mtx_lock_sleep((mp), _tid, (opts), (file), (line)); \ else \ LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, \ @@ -203,7 +203,7 @@ void thread_lock_flags_(struct thread *, int, const char *, int); uintptr_t _tid = (uintptr_t)(tid); \ \ spinlock_enter(); \ - if (!_mtx_obtain_lock((mp), _tid)) { \ + if (((mp)->mtx_lock != MTX_UNOWNED || !_mtx_obtain_lock((mp), _tid))) {\ if ((mp)->mtx_lock == _tid) \ (mp)->mtx_recurse++; \ else \ @@ -232,7 +232,7 @@ void thread_lock_flags_(struct thread *, int, const char *, int); \ if ((mp)->mtx_recurse == 0) \ LOCKSTAT_PROFILE_RELEASE_LOCK(adaptive__release, mp); \ - if (!_mtx_release_lock((mp), _tid)) \ + if ((mp)->mtx_lock != _tid || !_mtx_release_lock((mp), _tid)) \ _mtx_unlock_sleep((mp), (opts), (file), (line)); \ } while (0) |
