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From: Andi Kleen <andi@firstfloor.org>
To: acme@kernel.org
Cc: peterz@infradead.org, jolsa@kernel.org,
	linux-kernel@vger.kernel.org, Andi Kleen <ak@linux.intel.com>
Subject: [PATCH 01/11] x86, perf: Support sysfs files depending on SMT status
Date: Wed, 27 Apr 2016 13:00:41 -0700
Message-ID: <1461787251-6702-2-git-send-email-andi@firstfloor.org> (raw)
In-Reply-To: <1461787251-6702-1-git-send-email-andi@firstfloor.org>

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

Add a way to show different sysfs events attributes depending on
HyperThreading is on or off. This is difficult to determine
early at boot, so we just do it dynamically when the sysfs
attribute is read.

v2:
Compute HT status only once in CPU online/offline hooks.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 arch/x86/events/core.c       | 35 +++++++++++++++++++++++++++++++++++
 arch/x86/events/perf_event.h | 19 +++++++++++++++++++
 include/linux/perf_event.h   |  7 +++++++
 3 files changed, 61 insertions(+)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 41d93d0e972b..f1411062ccfb 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -1477,6 +1477,7 @@ x86_pmu_notifier(struct notifier_block *self, unsigned long action, void *hcpu)
 	unsigned int cpu = (long)hcpu;
 	struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);
 	int i, ret = NOTIFY_OK;
+	bool ht_on;
 
 	switch (action & ~CPU_TASKS_FROZEN) {
 	case CPU_UP_PREPARE:
@@ -1496,6 +1497,7 @@ x86_pmu_notifier(struct notifier_block *self, unsigned long action, void *hcpu)
 			kfree(cpuc->kfree_on_online[i]);
 			cpuc->kfree_on_online[i] = NULL;
 		}
+		x86_pmu.ht_on = cpumask_weight(topology_sibling_cpumask(cpu)) > 1;
 		break;
 
 	case CPU_DYING:
@@ -1507,6 +1509,15 @@ x86_pmu_notifier(struct notifier_block *self, unsigned long action, void *hcpu)
 	case CPU_DEAD:
 		if (x86_pmu.cpu_dead)
 			x86_pmu.cpu_dead(cpu);
+		/* Recompute HT state for all CPUs on offline */
+		ht_on = false;
+		for_each_online_cpu (cpu) {
+			if (cpumask_weight(topology_sibling_cpumask(cpu)) > 1) {
+				ht_on = true;
+				break;
+			}
+		}
+		x86_pmu.ht_on = ht_on;
 		break;
 
 	default:
@@ -1616,6 +1627,30 @@ ssize_t events_sysfs_show(struct device *dev, struct device_attribute *attr, cha
 }
 EXPORT_SYMBOL_GPL(events_sysfs_show);
 
+ssize_t events_ht_sysfs_show(struct device *dev, struct device_attribute *attr,
+			  char *page)
+{
+	struct perf_pmu_events_ht_attr *pmu_attr =
+		container_of(attr, struct perf_pmu_events_ht_attr, attr);
+
+	/*
+	 * Report conditional events depending on Hyper-Threading.
+	 *
+	 * This is overly conservative as usually the HT special
+	 * handling is not needed if the other CPU thread is idle.
+	 *
+	 * Note this does not (cannot) handle the case when thread
+	 * siblings are invisible, for example with virtualization
+	 * if they are owned by some other guest.  The user tool
+	 * has to re-read when a thread sibling gets onlined later.
+	 */
+
+	return sprintf(page, "%s",
+			x86_pmu.ht_on ?
+			pmu_attr->event_str_ht :
+			pmu_attr->event_str_noht);
+}
+
 EVENT_ATTR(cpu-cycles,			CPU_CYCLES		);
 EVENT_ATTR(instructions,		INSTRUCTIONS		);
 EVENT_ATTR(cache-references,		CACHE_REFERENCES	);
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index 7d62a02f49a4..6ae84bb91402 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -622,6 +622,11 @@ struct x86_pmu {
 	 * Intel host/guest support (KVM)
 	 */
 	struct perf_guest_switch_msr *(*guest_get_msrs)(int *nr);
+
+	/*
+	 * Hyper Threading on?
+	 */
+	bool ht_on;
 };
 
 struct x86_perf_task_context {
@@ -667,6 +672,14 @@ static struct perf_pmu_events_attr event_attr_##v = {			\
 	.event_str	= str,						\
 };
 
+#define EVENT_ATTR_STR_HT(_name, v, noht, ht)				\
+static struct perf_pmu_events_ht_attr event_attr_##v = {		\
+	.attr		= __ATTR(_name, 0444, events_ht_sysfs_show, NULL),\
+	.id		= 0,						\
+	.event_str_noht	= noht,						\
+	.event_str_ht	= ht,						\
+}
+
 extern struct x86_pmu x86_pmu __read_mostly;
 
 static inline bool x86_pmu_has_lbr_callstack(void)
@@ -937,6 +950,12 @@ int p6_pmu_init(void);
 
 int knc_pmu_init(void);
 
+ssize_t events_sysfs_show(struct device *dev, struct device_attribute *attr,
+			  char *page);
+
+ssize_t events_ht_sysfs_show(struct device *dev, struct device_attribute *attr,
+			  char *page);
+
 static inline int is_ht_workaround_enabled(void)
 {
 	return !!(x86_pmu.flags & PMU_FL_EXCL_ENABLED);
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index a090700cccca..b293b89a276f 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1205,6 +1205,13 @@ struct perf_pmu_events_attr {
 	const char *event_str;
 };
 
+struct perf_pmu_events_ht_attr {
+	struct device_attribute attr;
+	u64 id;
+	const char *event_str_ht;
+	const char *event_str_noht;
+};
+
 ssize_t perf_event_sysfs_show(struct device *dev, struct device_attribute *attr,
 			      char *page);
 
-- 
2.5.5

  reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-27 20:00 Add top down metrics to perf stat Andi Kleen
2016-04-27 20:00 ` Andi Kleen [this message]
2016-04-28  8:06   ` [PATCH 01/11] x86, perf: Support sysfs files depending on SMT status Peter Zijlstra
2016-04-28  8:17     ` Peter Zijlstra
2016-04-27 20:00 ` [PATCH 02/11] x86, perf: Add Top Down events to Intel Core Andi Kleen
2016-04-27 20:00 ` [PATCH 03/11] x86, perf: Add Top Down events to Intel Atom Andi Kleen
2016-04-27 20:00 ` [PATCH 04/11] x86, perf: Use new ht_on flag in HT leak workaround Andi Kleen
2016-04-27 20:00 ` [PATCH 05/11] perf, tools: Parse an .aggr-per-core event attribute Andi Kleen
2016-04-27 20:00 ` [PATCH 06/11] perf, tools, stat: Force --per-core mode for .aggr-per-core aliases Andi Kleen
2016-04-27 20:00 ` [PATCH 07/11] perf, tools, stat: Avoid fractional digits for integer scales Andi Kleen
2016-04-27 20:00 ` [PATCH 08/11] perf, tools, stat: Scale values by unit before metrics Andi Kleen
2016-04-27 20:00 ` [PATCH 09/11] perf, tools, stat: Basic support for TopDown in perf stat Andi Kleen
2016-04-27 20:00 ` [PATCH 10/11] perf, tools, stat: Add computation of TopDown formulas Andi Kleen
2016-04-27 20:00 ` [PATCH 11/11] perf, tools, stat: Add extra output of counter values with -vv Andi Kleen
2016-05-07  4:57   ` [tip:perf/core] perf " tip-bot for Andi Kleen
  -- strict thread matches above, loose matches on Subject: below --
2016-04-04 20:41 Add top down metrics to perf stat Andi Kleen
2016-04-04 20:41 ` [PATCH 01/11] x86, perf: Support sysfs files depending on SMT status Andi Kleen
2016-03-22 23:08 Add top down metrics to perf stat Andi Kleen
2016-03-22 23:08 ` [PATCH 01/11] x86, perf: Support sysfs files depending on SMT status Andi Kleen

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