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Tidy up hardclock.

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- use fcmpset for updating ticks
- move (rarely used) itimer handling to a dedicated function

Sponsored by:	The FreeBSD Foundation
This commit is contained in:
mjg 2018-11-29 03:44:02 +00:00
parent 0ed135f404
commit 23115d3e81
1 changed files with 39 additions and 27 deletions
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66
sys/kern/kern_clock.c
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@ -421,36 +421,14 @@ initclocks(void *dummy)
#endif
}
void
hardclock(int cnt, int usermode)
static __noinline void
hardclock_itimer(struct thread *td, struct pstats *pstats, int cnt, int usermode)
{
struct pstats *pstats;
struct thread *td = curthread;
struct proc *p = td->td_proc;
int *t = DPCPU_PTR(pcputicks);
int flags, global, newticks;
int i;
struct proc *p;
int flags;
/*
* Update per-CPU and possibly global ticks values.
*/
*t += cnt;
do {
global = ticks;
newticks = *t - global;
if (newticks <= 0) {
if (newticks < -1)
*t = global - 1;
newticks = 0;
break;
}
} while (!atomic_cmpset_int(&ticks, global, *t));
/*
* Run current process's virtual and profile time, as needed.
*/
pstats = p->p_stats;
flags = 0;
p = td->td_proc;
if (usermode &&
timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
PROC_ITIMLOCK(p);
@ -471,6 +449,40 @@ hardclock(int cnt, int usermode)
td->td_flags |= flags;
thread_unlock(td);
}
}
void
hardclock(int cnt, int usermode)
{
struct pstats *pstats;
struct thread *td = curthread;
struct proc *p = td->td_proc;
int *t = DPCPU_PTR(pcputicks);
int global, i, newticks;
/*
* Update per-CPU and possibly global ticks values.
*/
*t += cnt;
global = ticks;
do {
newticks = *t - global;
if (newticks <= 0) {
if (newticks < -1)
*t = global - 1;
newticks = 0;
break;
}
} while (!atomic_fcmpset_int(&ticks, &global, *t));
/*
* Run current process's virtual and profile time, as needed.
*/
pstats = p->p_stats;
if (__predict_false(
timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) ||
timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)))
hardclock_itimer(td, pstats, cnt, usermode);
#ifdef HWPMC_HOOKS
if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))