linux-kernel - [PATCH tip/core/rcu 11/12] torture: Grace periods do not piggyback off of themselves

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Date:   Mon, 26 Feb 2018 14:02:40 -0800
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 11/12] torture: Grace periods do not piggyback off of themselves

The rcuperf trace-event processing counted every "done" trace event
as a piggyback, which is incorrect because the task that started the
grace period didn't piggyback at all.  This commit fixes this problem
by recording the task that started a given grace period and ignoring
that task's "done" record for that grace period.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
 tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf-ftrace.sh | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf-ftrace.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf-ftrace.sh
index dffb553a7bcc..8948f7926b21 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf-ftrace.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcuperf-ftrace.sh
@@ -44,6 +44,7 @@ $8 == "start" {
 	starttask = $1;
 	starttime = $3;
 	startseq = $7;
+	seqtask[startseq] = starttask;
 }
 
 $8 == "end" {
@@ -62,7 +63,7 @@ $8 == "end" {
 	}
 }
 
-$8 == "done" {
+$8 == "done" && seqtask[$7] != $1 {
 	piggybackcnt[$1]++;
 }
 
-- 
2.5.2