linux-kernel - [patch] fix per task latencytop accumulator

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Message-ID: <AANLkTi=JKizQkRgY-ev21Cv_33hhxx7U9kpF_OQmp4ou@mail.gmail.com>
Date:	Mon, 8 Nov 2010 17:14:08 -0800
From:	Ken Chen <kenchen@...gle.com>
To:	linux-kernel@...r.kernel.org, arjan@...ux.intel.com,
	akpm@...ux-foundation.org
Subject: [patch] fix per task latencytop accumulator

Per task latencytop accumulator prematurely terminate due to erroneous
placement on latency_record_count.  It should be incremented whenever a
new record is allocated instead of increment on every latencytop event.

Also fix search iterator to only search known record events instead of
blindly search all pre-allocated space.

Signed-off-by: Ken Chen <kenchen@...gle.com>


diff --git a/kernel/latencytop.c b/kernel/latencytop.c
index 877fb30..17110a4 100644
--- a/kernel/latencytop.c
+++ b/kernel/latencytop.c
@@ -194,14 +194,7 @@ __account_scheduler_latency(

 	account_global_scheduler_latency(tsk, &lat);

-	/*
-	 * short term hack; if we're > 32 we stop; future we recycle:
-	 */
-	tsk->latency_record_count++;
-	if (tsk->latency_record_count >= LT_SAVECOUNT)
-		goto out_unlock;
-
-	for (i = 0; i < LT_SAVECOUNT; i++) {
+	for (i = 0; i < tsk->latency_record_count; i++) {
 		struct latency_record *mylat;
 		int same = 1;

@@ -227,8 +220,14 @@ __account_scheduler_latency(
 		}
 	}

+	/*
+	 * short term hack; if we're > 32 we stop; future we recycle:
+	 */
+	if (tsk->latency_record_count >= LT_SAVECOUNT)
+		goto out_unlock;
+
 	/* Allocated a new one: */
-	i = tsk->latency_record_count;
+	i = tsk->latency_record_count++;
 	memcpy(&tsk->latency_record[i], &lat, sizeof(struct latency_record));

 out_unlock:
--
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