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pmc_process_csw_out: ignore deleted counters

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I see the fllowing panic on AMD when exiting pmcstat:

panic: [pmc,1473] pp_pmcval outside of expected range cpu=2 ri=17
pp_pmcval=fffffffffa529f5b pm_reloadcount=10000

It seems that at least on AMD a performance counter keeps counting after
overflowing.  When pmcstat exits it sets counters that it used to
PMC_STATE_DELETED and waits until their use count goes to zero.
amd_intr() wouldn't reload a counter in that state and, thus, a counter
would be allowed to overflow.  That means that the counter's value would
be allowed to go outside the expected range.

MFC after:	2 weeks
This commit is contained in:
avg 2016-11-10 11:12:45 +00:00
parent 42837ed746
commit 959e19a84a
1 changed files with 2 additions and 2 deletions
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4
sys/dev/hwpmc/hwpmc_mod.c
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@ -1431,8 +1431,8 @@ pmc_process_csw_out(struct thread *td)
* save the reading.
*/
if (pp != NULL && pp->pp_pmcs[ri].pp_pmc != NULL) {
if (pm->pm_state != PMC_STATE_DELETED && pp != NULL &&
pp->pp_pmcs[ri].pp_pmc != NULL) {
KASSERT(pm == pp->pp_pmcs[ri].pp_pmc,
("[pmc,%d] pm %p != pp_pmcs[%d] %p", __LINE__,
pm, ri, pp->pp_pmcs[ri].pp_pmc));