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 04/22] perf/x86/lbr: Avoid reading the LBRs when adaptive PEBS handles them
Date: Mon, 18 Mar 2019 14:41:26 -0700 [thread overview]
Message-ID: <20190318214144.4639-5-kan.liang@linux.intel.com> (raw)
In-Reply-To: <20190318214144.4639-1-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>
---
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 58889f952959..b8cac31f089c 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 db3b622265fa..27c7945b5174 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -216,6 +216,7 @@ 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:[~2019-03-18 21:44 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-18 21:41 [PATCH 00/22] perf: Add Icelake support kan.liang
2019-03-18 21:41 ` [PATCH 01/22] perf/core: Support outputting registers from a separate array kan.liang
2019-03-19 13:00 ` Peter Zijlstra
2019-03-19 14:13 ` Peter Zijlstra
2019-03-18 21:41 ` [PATCH 02/22] perf/x86/intel: Extract memory code PEBS parser for reuse kan.liang
2019-03-19 13:14 ` Peter Zijlstra
2019-03-18 21:41 ` [PATCH 03/22] perf/x86/intel: Support adaptive PEBSv4 kan.liang
2019-03-19 14:47 ` Peter Zijlstra
2019-03-19 16:03 ` Andi Kleen
2019-03-19 16:11 ` Peter Zijlstra
2019-03-19 21:20 ` Liang, Kan
2019-03-19 21:38 ` Andi Kleen
2019-03-20 15:58 ` Peter Zijlstra
2019-03-18 21:41 ` kan.liang [this message]
2019-03-18 21:41 ` [PATCH 05/22] perf/x86: Support constraint ranges kan.liang
2019-03-19 14:53 ` Peter Zijlstra
2019-03-19 15:27 ` Peter Zijlstra
2019-03-19 15:57 ` Andi Kleen
2019-03-19 16:09 ` Peter Zijlstra
2019-03-18 21:41 ` [PATCH 06/22] perf/x86/intel: Add Icelake support kan.liang
2019-03-20 0:08 ` Stephane Eranian
2019-03-20 14:20 ` Liang, Kan
2019-03-18 21:41 ` [PATCH 07/22] perf/x86/intel/cstate: " kan.liang
2019-03-18 21:41 ` [PATCH 08/22] perf/x86/intel/rapl: " kan.liang
2019-03-18 21:41 ` [PATCH 09/22] perf/x86/msr: " kan.liang
2019-03-18 21:41 ` [PATCH 10/22] perf/x86/intel/uncore: Add Intel Icelake uncore support kan.liang
2019-03-18 21:41 ` [PATCH 11/22] perf/core: Support a REMOVE transaction kan.liang
2019-03-19 15:29 ` Peter Zijlstra
2019-03-18 21:41 ` [PATCH 12/22] perf/x86/intel: Basic support for metrics counters kan.liang
2019-03-18 21:41 ` [PATCH 13/22] perf/x86/intel: Support overflows on SLOTS kan.liang
2019-03-18 21:41 ` [PATCH 14/22] perf/x86/intel: Support hardware TopDown metrics kan.liang
2019-03-18 21:41 ` [PATCH 15/22] perf/x86/intel: Set correct weight for topdown subevent counters kan.liang
2019-03-18 21:41 ` [PATCH 16/22] perf/x86/intel: Export new top down events for Icelake kan.liang
2019-03-18 21:41 ` [PATCH 17/22] perf/x86/intel: Disable sampling read slots and topdown kan.liang
2019-03-18 21:41 ` [PATCH 18/22] perf/x86/intel: Support CPUID 10.ECX to disable fixed counters kan.liang
2019-03-18 21:41 ` [PATCH 19/22] perf, tools: Add support for recording and printing XMM registers kan.liang
2019-03-18 21:41 ` [PATCH 20/22] perf, tools, stat: Support new per thread TopDown metrics kan.liang
2019-03-18 21:41 ` [PATCH 21/22] perf, tools: Add documentation for topdown metrics kan.liang
2019-03-18 21:41 ` [PATCH 22/22] perf vendor events intel: Add JSON files for Icelake kan.liang
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