linux-kernel - [PATCH 1/4] perf/x86/cqm,mbm: Store cqm,mbm count for all events when RMID is recycled

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Date:	Fri, 22 Apr 2016 17:27:18 -0700
From:	Vikas Shivappa <vikas.shivappa@...ux.intel.com>
To:	tony.luck@...el.com, ravi.v.shankar@...el.com,
	fenghua.yu@...el.com, vikas.shivappa@...el.com,
	vikas.shivappa@...ux.intel.com
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org, hpa@...or.com,
	tglx@...utronix.de, mingo@...nel.org, peterz@...radead.org,
	h.peter.anvin@...el.com
Subject: [PATCH 1/4] perf/x86/cqm,mbm: Store cqm,mbm count for all events when RMID is recycled

During RMID recycling, when an event loses the RMID we saved the counter
for group leader but it was not being saved for all the events in an
event group. This would lead to a situation where if 2 perf instances
are counting the same PID one of them would not see the updated count
which other perf instance is seeing. This patch tries to fix the issue
by saving the count for all the events in the same event group.

Signed-off-by: Vikas Shivappa <vikas.shivappa@...ux.intel.com>
---
 arch/x86/events/intel/cqm.c | 39 ++++++++++++++++++++++++---------------
 1 file changed, 24 insertions(+), 15 deletions(-)

diff --git a/arch/x86/events/intel/cqm.c b/arch/x86/events/intel/cqm.c
index 7b5fd81..8dfba39 100644
--- a/arch/x86/events/intel/cqm.c
+++ b/arch/x86/events/intel/cqm.c
@@ -14,6 +14,14 @@
 #define MSR_IA32_QM_EVTSEL	0x0c8d
 
 #define MBM_CNTR_WIDTH		24
+
+#define __init_rr(old_rmid, config, val)	\
+((struct rmid_read) {				\
+	.rmid = old_rmid,			\
+	.evt_type = config,			\
+	.value = ATOMIC64_INIT(val),		\
+})
+
 /*
  * Guaranteed time in ms as per SDM where MBM counters will not overflow.
  */
@@ -478,7 +486,8 @@ static u32 intel_cqm_xchg_rmid(struct perf_event *group, u32 rmid)
 {
 	struct perf_event *event;
 	struct list_head *head = &group->hw.cqm_group_entry;
-	u32 old_rmid = group->hw.cqm_rmid;
+	u32 old_rmid = group->hw.cqm_rmid, evttype;
+	struct rmid_read rr;
 
 	lockdep_assert_held(&cache_mutex);
 
@@ -486,14 +495,21 @@ static u32 intel_cqm_xchg_rmid(struct perf_event *group, u32 rmid)
 	 * If our RMID is being deallocated, perform a read now.
 	 */
 	if (__rmid_valid(old_rmid) && !__rmid_valid(rmid)) {
-		struct rmid_read rr = {
-			.rmid = old_rmid,
-			.evt_type = group->attr.config,
-			.value = ATOMIC64_INIT(0),
-		};
 
+		rr = __init_rr(old_rmid, group->attr.config, 0);
 		cqm_mask_call(&rr);
 		local64_set(&group->count, atomic64_read(&rr.value));
+		list_for_each_entry(event, head, hw.cqm_group_entry) {
+			if (event->hw.is_group_event) {
+
+				evttype = event->attr.config;
+				rr = __init_rr(old_rmid, evttype, 0);
+
+				cqm_mask_call(&rr);
+					local64_set(&event->count,
+						    atomic64_read(&rr.value));
+			}
+		}
 	}
 
 	raw_spin_lock_irq(&cache_lock);
@@ -983,11 +999,7 @@ static void __intel_mbm_event_init(void *info)
 
 static void init_mbm_sample(u32 rmid, u32 evt_type)
 {
-	struct rmid_read rr = {
-		.rmid = rmid,
-		.evt_type = evt_type,
-		.value = ATOMIC64_INIT(0),
-	};
+	struct rmid_read rr = __init_rr(rmid, evt_type, 0);
 
 	/* on each socket, init sample */
 	on_each_cpu_mask(&cqm_cpumask, __intel_mbm_event_init, &rr, 1);
@@ -1181,10 +1193,7 @@ static void mbm_hrtimer_init(void)
 static u64 intel_cqm_event_count(struct perf_event *event)
 {
 	unsigned long flags;
-	struct rmid_read rr = {
-		.evt_type = event->attr.config,
-		.value = ATOMIC64_INIT(0),
-	};
+	struct rmid_read rr = __init_rr(-1, event->attr.config, 0);
 
 	/*
 	 * We only need to worry about task events. System-wide events
-- 
1.9.1