[patch] fix per task latencytop accumulator

From: Ken Chen
Date: Mon Nov 08 2010 - 20:14:15 EST


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@xxxxxxxxxx>


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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