Re: [PATCH 1/2] perf/x86/intel: Support adaptive PEBS for fixed counters

From: Liang, Kan
Date: Wed Apr 10 2019 - 09:57:56 EST




On 4/10/2019 3:41 AM, Peter Zijlstra wrote:
On Tue, Apr 09, 2019 at 06:09:59PM -0700, kan.liang@xxxxxxxxxxxxxxx wrote:
From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>

Fixed counters can also generate adaptive PEBS record, if the
corresponding bit in IA32_FIXED_CTR_CTRL is set.
Otherwise, only basic record is generated.

Unconditionally set the bit when PEBS is enabled on fixed counters.
Let MSR_PEBS_CFG decide which format of PEBS record should be generated.
There is no harmful to leave the bit set.

I'll merge this back into:

Subject: perf/x86/intel: Support adaptive PEBSv4

such that this bug never existed, ok?

Yes, please.

Thanks,
Kan



Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
---
arch/x86/events/intel/core.c | 5 +++++
arch/x86/include/asm/perf_event.h | 1 +
2 files changed, 6 insertions(+)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 56df0f6..f34d92b 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2174,6 +2174,11 @@ static void intel_pmu_enable_fixed(struct perf_event *event)
bits <<= (idx * 4);
mask = 0xfULL << (idx * 4);
+ if (x86_pmu.intel_cap.pebs_baseline && event->attr.precise_ip) {
+ bits |= ICL_FIXED_0_ADAPTIVE << (idx * 4);
+ mask |= ICL_FIXED_0_ADAPTIVE << (idx * 4);
+ }
+
rdmsrl(hwc->config_base, ctrl_val);
ctrl_val &= ~mask;
ctrl_val |= bits;
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index dcb8bac..ce0dc88 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -33,6 +33,7 @@
#define HSW_IN_TX (1ULL << 32)
#define HSW_IN_TX_CHECKPOINTED (1ULL << 33)
#define ICL_EVENTSEL_ADAPTIVE (1ULL << 34)
+#define ICL_FIXED_0_ADAPTIVE (1ULL << 32)
#define AMD64_EVENTSEL_INT_CORE_ENABLE (1ULL << 36)
#define AMD64_EVENTSEL_GUESTONLY (1ULL << 40)
--
2.7.4