From: kan.liang@linux.intel.com
To: peterz@infradead.org, acme@kernel.org, mingo@redhat.com,
linux-kernel@vger.kernel.org
Cc: tglx@linutronix.de, jolsa@kernel.org, eranian@google.com,
alexander.shishkin@linux.intel.com, ak@linux.intel.com,
Kan Liang <kan.liang@linux.intel.com>
Subject: [PATCH V5 06/12] perf/x86/lbr: Avoid reading the LBRs when adaptive PEBS handles them
Date: Tue, 2 Apr 2019 12:45:03 -0700 [thread overview]
Message-ID: <20190402194509.2832-7-kan.liang@linux.intel.com> (raw)
In-Reply-To: <20190402194509.2832-1-kan.liang@linux.intel.com>
From: Andi Kleen <ak@linux.intel.com>
With adaptive PEBS the CPU can directly supply the LBR information,
so we don't need to read it again. But the LBRs still need to be
enabled. Add a special count to the cpuc that distinguishes these
two cases, and avoid reading the LBRs unnecessarily when PEBS is
active.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
---
No changes since V4.
arch/x86/events/intel/lbr.c | 13 ++++++++++++-
arch/x86/events/perf_event.h | 1 +
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index 07b7175fc378..6f814a27416b 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -488,6 +488,8 @@ void intel_pmu_lbr_add(struct perf_event *event)
* be 'new'. Conversely, a new event can get installed through the
* context switch path for the first time.
*/
+ if (x86_pmu.intel_cap.pebs_baseline && event->attr.precise_ip > 0)
+ cpuc->lbr_pebs_users++;
perf_sched_cb_inc(event->ctx->pmu);
if (!cpuc->lbr_users++ && !event->total_time_running)
intel_pmu_lbr_reset();
@@ -507,8 +509,11 @@ void intel_pmu_lbr_del(struct perf_event *event)
task_ctx->lbr_callstack_users--;
}
+ if (x86_pmu.intel_cap.pebs_baseline && event->attr.precise_ip > 0)
+ cpuc->lbr_pebs_users--;
cpuc->lbr_users--;
WARN_ON_ONCE(cpuc->lbr_users < 0);
+ WARN_ON_ONCE(cpuc->lbr_pebs_users < 0);
perf_sched_cb_dec(event->ctx->pmu);
}
@@ -658,7 +663,13 @@ void intel_pmu_lbr_read(void)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
- if (!cpuc->lbr_users)
+ /*
+ * Don't read when all LBRs users are using adaptive PEBS.
+ *
+ * This could be smarter and actually check the event,
+ * but this simple approach seems to work for now.
+ */
+ if (!cpuc->lbr_users || cpuc->lbr_users == cpuc->lbr_pebs_users)
return;
if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_32)
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index d95014f88ef7..089c38e3d2bf 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -234,6 +234,7 @@ struct cpu_hw_events {
* Intel LBR bits
*/
int lbr_users;
+ int lbr_pebs_users;
struct perf_branch_stack lbr_stack;
struct perf_branch_entry lbr_entries[MAX_LBR_ENTRIES];
struct er_account *lbr_sel;
--
2.17.1
next prev parent reply other threads:[~2019-04-02 19:48 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-02 19:44 [PATCH V5 00/12] perf: Add Icelake support (kernel only, except Topdown) kan.liang
2019-04-02 19:44 ` [PATCH V5 01/12] perf/x86: Fix wrong PEBS_REGS kan.liang
2019-04-16 11:32 ` [tip:perf/core] perf/x86: Fix incorrect PEBS_REGS tip-bot for Kan Liang
2019-04-02 19:44 ` [PATCH V5 02/12] perf/x86: Support outputting XMM registers kan.liang
2019-04-16 11:34 ` [tip:perf/core] " tip-bot for Kan Liang
2019-04-02 19:45 ` [PATCH V5 03/12] perf/x86/intel: Extract memory code PEBS parser for reuse kan.liang
2019-04-16 11:35 ` [tip:perf/core] " tip-bot for Andi Kleen
2019-04-02 19:45 ` [PATCH V5 04/12] perf/x86/intel/ds: Extract code of event update in short period kan.liang
2019-04-16 11:35 ` [tip:perf/core] " tip-bot for Kan Liang
2019-04-02 19:45 ` [PATCH V5 05/12] perf/x86/intel: Support adaptive PEBSv4 kan.liang
2019-04-08 14:55 ` Peter Zijlstra
2019-04-16 11:36 ` [tip:perf/core] perf/x86/intel: Support adaptive PEBS v4 tip-bot for Kan Liang
2019-04-02 19:45 ` kan.liang [this message]
2019-04-16 11:37 ` [tip:perf/core] perf/x86/lbr: Avoid reading the LBRs when adaptive PEBS handles them tip-bot for Andi Kleen
2019-04-02 19:45 ` [PATCH V5 07/12] perf/x86: Support constraint ranges kan.liang
2019-04-16 11:37 ` [tip:perf/core] " tip-bot for Peter Zijlstra
2019-04-02 19:45 ` [PATCH V5 08/12] perf/x86/intel: Add Icelake support kan.liang
2019-04-08 15:06 ` Peter Zijlstra
2019-04-08 15:45 ` Liang, Kan
2019-04-10 18:22 ` Liang, Kan
2019-04-10 19:47 ` Peter Zijlstra
2019-04-11 9:00 ` Peter Zijlstra
2019-04-11 13:29 ` Liang, Kan
2019-04-16 11:38 ` [tip:perf/core] " tip-bot for Kan Liang
2019-04-02 19:45 ` [PATCH V5 09/12] perf/x86/intel/cstate: " kan.liang
2019-04-16 11:39 ` [tip:perf/core] " tip-bot for Kan Liang
2019-04-02 19:45 ` [PATCH V5 10/12] perf/x86/intel/rapl: " kan.liang
2019-04-16 11:39 ` [tip:perf/core] " tip-bot for Kan Liang
2019-04-02 19:45 ` [PATCH V5 11/12] perf/x86/msr: " kan.liang
2019-04-16 11:40 ` [tip:perf/core] " tip-bot for Kan Liang
2019-04-02 19:45 ` [PATCH V5 12/12] perf/x86/intel/uncore: Add Intel Icelake uncore support kan.liang
2019-04-16 11:40 ` [tip:perf/core] " tip-bot for Kan Liang
2019-04-08 15:41 ` [PATCH V5 00/12] perf: Add Icelake support (kernel only, except Topdown) Peter Zijlstra
2019-04-08 16:06 ` Liang, Kan
2019-04-08 16:25 ` Liang, Kan
2019-04-08 16:28 ` Peter Zijlstra
2019-04-08 22:49 ` Liang, Kan
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