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Groups > linux.kernel > #1283394

[PATCH 1/2] x86, perf: Remove warning for zero PEBS status

From Andi Kleen <andi@firstfloor.org>
Newsgroups linux.kernel
Subject [PATCH 1/2] x86, perf: Remove warning for zero PEBS status
Date 2015-12-03 22:30 +0100
Message-ID <qBJBU-22d-3@gated-at.bofh.it> (permalink)
Organization linux.* mail to news gateway

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From: Andi Kleen <ak@linux.intel.com>

The recent change 75f80859b1 (... Robustify PEBS buffer drain)
causes lots of warnings on different CPUs before Skylake
when running PEBS intensive workloads.

They can have a zero status field in the PEBS record when
PEBS is racing with clearing of GLOBAl_STATUS.

This also can cause hangs (it seems there are still
problems with printk in NMI)

Disable the warning, but still ignore the record.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 arch/x86/kernel/cpu/perf_event_intel_ds.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index 7f11784..da294de 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -1237,10 +1237,7 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
 
 		bit = find_first_bit((unsigned long *)&pebs_status,
 					x86_pmu.max_pebs_events);
-		if (WARN(bit >= x86_pmu.max_pebs_events,
-			 "PEBS record without PEBS event! status=%Lx pebs_enabled=%Lx active_mask=%Lx",
-			 (unsigned long long)p->status, (unsigned long long)cpuc->pebs_enabled,
-			 *(unsigned long long *)cpuc->active_mask))
+		if (bit >= x86_pmu.max_pebs_events)
 			continue;
 
 		/*
-- 
2.4.3

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[PATCH 1/2] x86, perf: Remove warning for zero PEBS status Andi Kleen <andi@firstfloor.org> - 2015-12-03 22:30 +0100
  Re: [PATCH 1/2] x86, perf: Remove warning for zero PEBS status Peter Zijlstra <peterz@infradead.org> - 2015-12-03 22:30 +0100

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