diff options
| author | Ben Gamari <ben@smart-cactus.org> | 2020-10-29 16:14:29 -0400 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2020-10-30 14:02:19 -0400 |
| commit | 105d43db7bb7f399be3e5474d207e330d1b2da5a (patch) | |
| tree | 7503c1b1f78e841d6439e2aec745f3b39c54bf11 /includes | |
| parent | a80cc8577774a744d684cd1f513e373405cd2f2b (diff) | |
| download | haskell-105d43db7bb7f399be3e5474d207e330d1b2da5a.tar.gz | |
rts/SpinLock: Separate out slow path
Not only is this in general a good idea, but it turns out that GCC
unrolls the retry loop, resulting is massive code bloat in critical
parts of the RTS (e.g. `evacuate`).
Diffstat (limited to 'includes')
| -rw-r--r-- | includes/rts/SpinLock.h | 15 |
1 files changed, 5 insertions, 10 deletions
diff --git a/includes/rts/SpinLock.h b/includes/rts/SpinLock.h index 0ac51455dd..c1fe6c866c 100644 --- a/includes/rts/SpinLock.h +++ b/includes/rts/SpinLock.h @@ -39,19 +39,14 @@ typedef struct SpinLock_ #define IF_PROF_SPIN(x) #endif +void acquire_spin_lock_slow_path(SpinLock * p); + // acquire spin lock INLINE_HEADER void ACQUIRE_SPIN_LOCK(SpinLock * p) { - do { - for (uint32_t i = 0; i < SPIN_COUNT; i++) { - StgWord32 r = cas((StgVolatilePtr)&(p->lock), 1, 0); - if (r != 0) return; - IF_PROF_SPIN(__atomic_fetch_add(&p->spin, 1, __ATOMIC_RELAXED)); - busy_wait_nop(); - } - IF_PROF_SPIN(__atomic_fetch_add(&p->yield, 1, __ATOMIC_RELAXED)); - yieldThread(); - } while (1); + StgWord32 r = cas((StgVolatilePtr)&(p->lock), 1, 0); + if (RTS_UNLIKELY(r == 0)) + acquire_spin_lock_slow_path(p); } // release spin lock |