linux-kernel - [PATCH 11/12] perf kvm: only process events for vcpus of interest

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Date:	Mon,  8 Oct 2012 11:17:35 -0600
From:	David Ahern <dsahern@...il.com>
To:	acme@...stprotocols.net, linux-kernel@...r.kernel.org
Cc:	mingo@...nel.org, peterz@...radead.org, fweisbec@...il.com,
	David Ahern <dsahern@...il.com>,
	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>,
	Dong Hao <haodong@...ux.vnet.ibm.com>
Subject: [PATCH 11/12] perf kvm: only process events for vcpus of interest

Minimizing processing overhead for each sample - which becomes important
for the upcoming live mode when it has to deal with 100+k events per
second.

Signed-off-by: David Ahern <dsahern@...il.com>
Cc: Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
Cc: Dong Hao <haodong@...ux.vnet.ibm.com>
---
 tools/perf/builtin-kvm.c |   18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index 6412694..dcbbcc7 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -420,7 +420,10 @@ static double kvm_event_rel_stddev(int vcpu_id, struct kvm_event *event)
 static bool update_kvm_event(struct kvm_event *event, int vcpu_id,
 			     u64 time_diff)
 {
-	kvm_update_event_stats(&event->total, time_diff);
+	if (vcpu_id == -1) {
+		kvm_update_event_stats(&event->total, time_diff);
+		return true;
+	}
 
 	if (!kvm_event_expand(event, vcpu_id))
 		return false;
@@ -436,6 +439,12 @@ static bool handle_end_event(struct perf_kvm *kvm,
 {
 	struct kvm_event *event;
 	u64 time_begin, time_diff;
+	int vcpu;
+
+	if (kvm->trace_vcpu == -1)
+		vcpu = -1;
+	else
+		vcpu = vcpu_record->vcpu_id;
 
 	event = vcpu_record->last_event;
 	time_begin = vcpu_record->start_time;
@@ -465,7 +474,7 @@ static bool handle_end_event(struct perf_kvm *kvm,
 	BUG_ON(timestamp < time_begin);
 
 	time_diff = timestamp - time_begin;
-	return update_kvm_event(event, vcpu_record->vcpu_id, time_diff);
+	return update_kvm_event(event, vcpu, time_diff);
 }
 
 static
@@ -502,6 +511,11 @@ static bool handle_kvm_event(struct perf_kvm *kvm,
 	if (!vcpu_record)
 		return true;
 
+	/* only process events for vcpus user cares about */
+	if ((kvm->trace_vcpu != -1) &&
+	    (kvm->trace_vcpu != vcpu_record->vcpu_id))
+		return true;
+
 	if (kvm->events_ops->is_begin_event(evsel, sample, &key))
 		return handle_begin_event(kvm, vcpu_record, &key, sample->time);
 
-- 
1.7.10.1

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