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hwpstate: use CPU_FOREACH when binding to all available processors

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Also, add a comment mentioning _PSD - on some systems it's enough to
put one logical CPU into a particular P-state to make other CPUs in
the same domain to enter that P-state.

Also, call sched_unbind() after the loop - sched_bind() automatically
rebinds from previous CPU to a new one, and the new arrangement of code
is safer against early loop exit.

Plus one minor style nit.

MFC after:	10 days
This commit is contained in:
Andriy Gapon 2010-11-16 12:43:45 +00:00
parent f9e2e99d5d
commit 40934baa60
1 changed files with 8 additions and 12 deletions
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20
sys/x86/cpufreq/hwpstate.c
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@ -157,7 +157,6 @@ DRIVER_MODULE(hwpstate, cpu, hwpstate_driver, hwpstate_devclass, 0, 0);
static int
hwpstate_goto_pstate(device_t dev, int pstate)
{
struct pcpu *pc;
int i;
uint64_t msr;
int j;
@ -171,18 +170,15 @@ hwpstate_goto_pstate(device_t dev, int pstate)
if(limit > id)
id = limit;
error = 0;
/*
* We are going to the same Px-state on all cpus.
* Probably should take _PSD into account.
*/
for (i = 0; i < mp_ncpus; i++) {
/* Find each cpu. */
pc = pcpu_find(i);
if (pc == NULL)
return (ENXIO);
thread_lock(curthread);
error = 0;
CPU_FOREACH(i) {
/* Bind to each cpu. */
sched_bind(curthread, pc->pc_cpuid);
thread_lock(curthread);
sched_bind(curthread, i);
thread_unlock(curthread);
HWPSTATE_DEBUG(dev, "setting P%d-state on cpu%d\n",
id, PCPU_GET(cpuid));
@ -204,10 +200,10 @@ hwpstate_goto_pstate(device_t dev, int pstate)
HWPSTATE_DEBUG(dev, "error: loop is not enough.\n");
error = ENXIO;
}
thread_lock(curthread);
sched_unbind(curthread);
thread_unlock(curthread);
}
thread_lock(curthread);
sched_unbind(curthread);
thread_unlock(curthread);
return (error);
}