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.
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=212601
@ -374,8 +374,7 @@ int ticks;
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int psratio;
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static DPCPU_DEFINE(int, pcputicks); /* Per-CPU version of ticks. */
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static struct mtx global_hardclock_mtx;
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MTX_SYSINIT(global_hardclock_mtx, &global_hardclock_mtx, "ghc_mtx", MTX_SPIN);
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static int global_hardclock_run = 0;
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/*
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* Initialize clock frequencies and start both clocks running.
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@ -485,8 +484,10 @@ hardclock_anycpu(int cnt, int usermode)
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struct thread *td = curthread;
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struct proc *p = td->td_proc;
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int *t = DPCPU_PTR(pcputicks);
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int flags;
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int global, newticks;
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int flags, global, newticks;
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#ifdef SW_WATCHDOG
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int i;
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#endif /* SW_WATCHDOG */
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/*
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* Update per-CPU and possibly global ticks values.
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@ -535,19 +536,22 @@ hardclock_anycpu(int cnt, int usermode)
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callout_tick();
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/* We are in charge to handle this tick duty. */
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if (newticks > 0) {
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mtx_lock_spin(&global_hardclock_mtx);
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tc_ticktock();
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/* Dangerous and no need to call these things concurrently. */
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if (atomic_cmpset_acq_int(&global_hardclock_run, 0, 1)) {
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tc_ticktock();
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#ifdef DEVICE_POLLING
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hardclock_device_poll(); /* This is very short and quick. */
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/* This is very short and quick. */
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hardclock_device_poll();
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#endif /* DEVICE_POLLING */
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atomic_store_rel_int(&global_hardclock_run, 0);
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}
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#ifdef SW_WATCHDOG
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if (watchdog_enabled > 0) {
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watchdog_ticks -= newticks;
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if (watchdog_ticks <= 0)
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i = atomic_fetchadd_int(&watchdog_ticks, -newticks);
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if (i > 0 && i <= newticks)
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watchdog_fire();
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}
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#endif /* SW_WATCHDOG */
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mtx_unlock_spin(&global_hardclock_mtx);
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}
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if (curcpu == CPU_FIRST())
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cpu_tick_calibration();
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