Re: [PATCH 1/2] powerpc/perf: Fix finding overflowed PMC in interrupt
flat view
From: Anshuman Khandual <hidden>
Date: 2012-11-06 06:47:26
On 11/06/2012 07:23 AM, Michael Neuling wrote:
quoted hunk ↗ jump to hunk
+ if (!found && pvr_version_is(PVR_POWER7)) { + /* check active counters for special buggy p7 overflow */ + for (i = 0; i < cpuhw->n_events; ++i) { + event = cpuhw->event[i]; + if (!event->hw.idx || is_limited_pmc(event->hw.idx)) continue; - val = read_pmc(i + 1); - if (pmc_overflow(val)) - write_pmc(i + 1, 0); + if (pmc_overflow_power7(val[event->hw.idx - 1])) {
I have couple of questions. Can the buggy overflow happen on any of the available counters PMC1-PMC4 ? Will this approach never reset an actual user defined event (with sample period < 256) ? Is this related to the counter or the event which it is counting ? Just wondering if we have to do something more than checking for the count < 256. Just a thought. Regards Anshuman