Re: [PATCH V4 1/5] perf/x86/intel: Fix event update for auto-reload

[Liang, Kan]

On 2/21/2018 5:32 AM, Peter Zijlstra wrote:

On Mon, Feb 12, 2018 at 02:20:31PM -0800, kan.li...@linux.intel.com wrote:

@@ -1389,8 +1456,22 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs 
*iregs)

ds->pebs_index = ds->pebs_buffer_base; - if (unlikely(base >= top))

+       if (unlikely(base >= top)) {
+               /*
+                * The drain_pebs() could be called twice in a short period
+                * for auto-reload event in pmu::read(). There are no
+                * overflows have happened in between.
+                * It needs to call intel_pmu_save_and_restart_reload() to
+                * update the event->count for this case.
+                */
+               for_each_set_bit(bit, (unsigned long *)&cpuc->pebs_enabled,
+                                x86_pmu.max_pebs_events) {
+                       event = cpuc->events[bit];
+                       if (event->hw.flags & PERF_X86_EVENT_AUTO_RELOAD)
+                               intel_pmu_save_and_restart_reload(event, 0);
+               }
                return;
+       }

for (at = base; at < top; at += x86_pmu.pebs_record_size) {

                struct pebs_record_nhm *p = at;

Is there a reason you didn't do intel_pmu_drain_pebs_core() ?

Right, I forgot that the drain_pebs_core() also has auto_reload support.
Sorry for that.
I will re-send all patches.

Thanks,
Kan

--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1435,8 +1435,11 @@ static void intel_pmu_drain_pebs_core(st
                return;

n = top - at;

-       if (n <= 0)
+       if (n <= 0) {
+               if (event->hw.flags & PERF_X86_EVENT_AUTO_RELOAD)
+                       intel_pmu_save_and_restart_reload(event, 0);
                return;
+       }

__intel_pmu_pebs_event(event, iregs, at, top, 0, n);

  }