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perf/x86: Fix n_pair for cancelled txn

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Kan reported that n_metric gets corrupted for cancelled transactions;
a similar issue exists for n_pair for AMD's Large Increment thing.

The problem was confirmed and confirmed fixed by Kim using:

  sudo perf stat -e "{cycles,cycles,cycles,cycles}:D" -a sleep 10 &

  # should succeed:
  sudo perf stat -e "{fp_ret_sse_avx_ops.all}:D" -a workload

  # should fail:
  sudo perf stat -e "{fp_ret_sse_avx_ops.all,fp_ret_sse_avx_ops.all,cycles}:D" -a workload

  # previously failed, now succeeds with this patch:
  sudo perf stat -e "{fp_ret_sse_avx_ops.all}:D" -a workload

Fixes: 5738891229 ("perf/x86/amd: Add support for Large Increment per Cycle Events")
Reported-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Kim Phillips <kim.phillips@amd.com>
Link: https://lkml.kernel.org/r/20201005082516.GG2628@hirez.programming.kicks-ass.net
This commit is contained in:
Peter Zijlstra 2020-10-05 10:09:06 +02:00
parent 59d5396a46
commit 871a93b0aa
2 changed files with 6 additions and 1 deletions
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6
arch/x86/events/core.c
View File

@ -1064,8 +1064,10 @@ static int collect_event(struct cpu_hw_events *cpuc, struct perf_event *event,
return -EINVAL;
cpuc->event_list[n] = event;
if (is_counter_pair(&event->hw))
if (is_counter_pair(&event->hw)) {
cpuc->n_pair++;
cpuc->n_txn_pair++;
}
return 0;
}
@ -2006,6 +2008,7 @@ static void x86_pmu_start_txn(struct pmu *pmu, unsigned int txn_flags)
perf_pmu_disable(pmu);
__this_cpu_write(cpu_hw_events.n_txn, 0);
__this_cpu_write(cpu_hw_events.n_txn_pair, 0);
}
/*
@ -2031,6 +2034,7 @@ static void x86_pmu_cancel_txn(struct pmu *pmu)
*/
__this_cpu_sub(cpu_hw_events.n_added, __this_cpu_read(cpu_hw_events.n_txn));
__this_cpu_sub(cpu_hw_events.n_events, __this_cpu_read(cpu_hw_events.n_txn));
__this_cpu_sub(cpu_hw_events.n_pair, __this_cpu_read(cpu_hw_events.n_txn_pair));
perf_pmu_enable(pmu);
}

1
arch/x86/events/perf_event.h
View File

@ -235,6 +235,7 @@ struct cpu_hw_events {
they've never been enabled yet */
int n_txn; /* the # last events in the below arrays;
added in the current transaction */
int n_txn_pair;
int assign[X86_PMC_IDX_MAX]; /* event to counter assignment */
u64 tags[X86_PMC_IDX_MAX];