Messages in this thread | | | From | "Liang, Kan" <> | Subject | RE: [PATCH V7 3/6] perf, x86: handle multiple records in PEBS buffer | Date | Tue, 5 May 2015 17:22:38 +0000 |
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> On Tue, May 05, 2015 at 04:30:25PM +0000, Liang, Kan wrote: > > > > + for (at = base; at < top; at += x86_pmu.pebs_record_size) { > > > > struct pebs_record_nhm *p = at; > > > > > > > > for_each_set_bit(bit, (unsigned long *)&p->status, > > > > x86_pmu.max_pebs_events) { > > > > event = cpuc->events[bit]; > > > > WARN_ON_ONCE(!event); > > > > > > > > + if (event->attr.precise_ip) > > > > + break; > > > > + } > > > > > > Would it make sense to delay looking for the event until you've > > > found there is a single bit set -- and already know which bit that is? > > > > > > > Yes, I think we can test cpuc->pebs_enabled here. > > It should be better than attr.precise_ip checking. > > > > - for (; at < top; at += x86_pmu.pebs_record_size) { > > + for (at = base; at < top; at += x86_pmu.pebs_record_size) { > > struct pebs_record_nhm *p = at; > > > > for_each_set_bit(bit, (unsigned long *)&p->status, > > x86_pmu.max_pebs_events) { > > - event = cpuc->events[bit]; > > - if (!test_bit(bit, cpuc->active_mask)) > > - continue; > > - > > - WARN_ON_ONCE(!event); > > > > - if (!event->attr.precise_ip) > > - continue; > > + if (test_bit(bit, cpuc->pebs_enabled)) > > + break; > > + } > > > > Can't we take that entire for_each_set_bit() loop out? > > It appears to me we effectively do that single test_bit() test you left in > there already with the & cpuc->pebs_enabled later on. > > Right, will use find_first_bit to replace.
+ for (at = base; at < top; at += x86_pmu.pebs_record_size) { struct pebs_record_nhm *p = at;
- for_each_set_bit(bit, (unsigned long *)&p->status, - x86_pmu.max_pebs_events) { - event = cpuc->events[bit]; - if (!test_bit(bit, cpuc->active_mask)) - continue; - - WARN_ON_ONCE(!event); - - if (!event->attr.precise_ip) - continue; - - if (__test_and_set_bit(bit, (unsigned long *)&status)) + bit = find_first_bit((unsigned long *)&p->status, + x86_pmu.max_pebs_events);
Thanks, Kan
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