linux-kernel - [PATCH 1/6] cpufreq_stats: Correct jiffies64/cputime64 conversion

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Message-ID: <20081125214442.22900.20172.stgit@elm3a70.beaverton.ibm.com>
Date:	Tue, 25 Nov 2008 13:44:42 -0800
From:	"Darrick J. Wong" <djwong@...ibm.com>
To:	"Darrick J. Wong" <djwong@...ibm.com>,
	Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
	Dipankar Sarma <dipankar.sarma@...ibm.com>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>
Subject: [PATCH 1/6] cpufreq_stats: Correct jiffies64/cputime64 conversion

Since cpufreq_stats->time_in_state is a cputime64_t value, we ought
to convert the jiffies64 values to cputime64_t.  On platforms where
cputime != jiffies, this leads to accounting errors in the sysfs
reports.

Signed-off-by: Darrick J. Wong <djwong@...ibm.com>
---
 drivers/cpufreq/cpufreq_stats.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index c0ff97d..b5ccf86 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -55,14 +55,18 @@ cpufreq_stats_update (unsigned int cpu)
 {
 	struct cpufreq_stats *stat;
 	unsigned long long cur_time;
+	cputime64_t d;
 
 	cur_time = get_jiffies_64();
 	spin_lock(&cpufreq_stats_lock);
 	stat = per_cpu(cpufreq_stats_table, cpu);
-	if (stat->time_in_state)
+	if (stat->time_in_state) {
+		d = jiffies64_to_cputime64(cputime_sub(cur_time,
+					   stat->last_time));
 		stat->time_in_state[stat->last_index] =
 			cputime64_add(stat->time_in_state[stat->last_index],
-				      cputime_sub(cur_time, stat->last_time));
+				      d);
+	}
 	stat->last_time = cur_time;
 	spin_unlock(&cpufreq_stats_lock);
 	return 0;

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