diff options
author | mav <mav@FreeBSD.org> | 2010-09-14 04:57:30 +0000 |
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committer | mav <mav@FreeBSD.org> | 2010-09-14 04:57:30 +0000 |
commit | 5864d6e457c81a0a80b2ab3b57ee852e6f62efcb (patch) | |
tree | 7ebc0caf40fbbb671d81071747111bf265d27381 /sys/kern/kern_clock.c | |
parent | 5f7bd119f789c2177608328cdeed25a4f22997f8 (diff) | |
download | FreeBSD-src-5864d6e457c81a0a80b2ab3b57ee852e6f62efcb.zip FreeBSD-src-5864d6e457c81a0a80b2ab3b57ee852e6f62efcb.tar.gz |
Replace spin lock with the set of atomics. It is impractical for one
tc_ticktock() call to wait for another's completion -- just skip it.
Diffstat (limited to 'sys/kern/kern_clock.c')
-rw-r--r-- | sys/kern/kern_clock.c | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/sys/kern/kern_clock.c b/sys/kern/kern_clock.c index ff5747e..7fb70d0 100644 --- a/sys/kern/kern_clock.c +++ b/sys/kern/kern_clock.c @@ -374,8 +374,7 @@ int ticks; int psratio; static DPCPU_DEFINE(int, pcputicks); /* Per-CPU version of ticks. */ -static struct mtx global_hardclock_mtx; -MTX_SYSINIT(global_hardclock_mtx, &global_hardclock_mtx, "ghc_mtx", MTX_SPIN); +static int global_hardclock_run = 0; /* * Initialize clock frequencies and start both clocks running. @@ -485,8 +484,10 @@ hardclock_anycpu(int cnt, int usermode) struct thread *td = curthread; struct proc *p = td->td_proc; int *t = DPCPU_PTR(pcputicks); - int flags; - int global, newticks; + int flags, global, newticks; +#ifdef SW_WATCHDOG + int i; +#endif /* SW_WATCHDOG */ /* * Update per-CPU and possibly global ticks values. @@ -535,19 +536,22 @@ hardclock_anycpu(int cnt, int usermode) callout_tick(); /* We are in charge to handle this tick duty. */ if (newticks > 0) { - mtx_lock_spin(&global_hardclock_mtx); - tc_ticktock(); + /* Dangerous and no need to call these things concurrently. */ + if (atomic_cmpset_acq_int(&global_hardclock_run, 0, 1)) { + tc_ticktock(); #ifdef DEVICE_POLLING - hardclock_device_poll(); /* This is very short and quick. */ + /* This is very short and quick. */ + hardclock_device_poll(); #endif /* DEVICE_POLLING */ + atomic_store_rel_int(&global_hardclock_run, 0); + } #ifdef SW_WATCHDOG if (watchdog_enabled > 0) { - watchdog_ticks -= newticks; - if (watchdog_ticks <= 0) + i = atomic_fetchadd_int(&watchdog_ticks, -newticks); + if (i > 0 && i <= newticks) watchdog_fire(); } #endif /* SW_WATCHDOG */ - mtx_unlock_spin(&global_hardclock_mtx); } if (curcpu == CPU_FIRST()) cpu_tick_calibration(); |