Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751060Ab3IGQfR (ORCPT ); Sat, 7 Sep 2013 12:35:17 -0400 Received: from mail-wi0-f178.google.com ([209.85.212.178]:49153 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750944Ab3IGQfP (ORCPT ); Sat, 7 Sep 2013 12:35:15 -0400 From: Frederic Weisbecker To: "Rafael J. Wysocki" , Viresh Kumar Cc: LKML , Frederic Weisbecker , Carsten Emde , Thomas Gleixner , Clark Williams , Sebastian Andrzej Siewior , "Paul E. McKenney" Subject: [PATCH] cpufreq: Fix wrong time unit conversion Date: Sat, 7 Sep 2013 18:35:08 +0200 Message-Id: <1378571708-27825-1-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.7.5.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2331 Lines: 62 The time spent by a CPU under a given frequency is stored in jiffies unit in the cpu var cpufreq_stats_table->time_in_state[i], i being the index of the frequency. This is what is displayed in the following file on the right column: cat /sys/devices/system/cpu/cpuX/cpufreq/stats/time_in_state 2301000 19835820 2300000 3172 [...] Now cpufreq converts this jiffies unit delta to clock_t before returning it to the user as in the above file. And that conversion is achieved using the API cputime64_to_clock_t(). Although it accidentally works on traditional tick based cputime accounting, where cputime_t maps directly to jiffies, it doesn't work with other types of cputime accounting such as CONFIG_VIRT_CPU_ACCOUNTING_* where cputime_t can map to nsecs or any granularity preffered by the architecture. For example we get a buggy zero delta on full dyntick configurations: cat /sys/devices/system/cpu/cpuX/cpufreq/stats/time_in_state 2301000 0 2300000 0 [...] Fix this with using the proper jiffies_64_t to clock_t conversion. Reported-by: Carsten Emde Tested-by: Carsten Emde Signed-off-by: Frederic Weisbecker Cc: Carsten Emde Cc: Thomas Gleixner Cc: Clark Williams Cc: Sebastian Andrzej Siewior Cc: Paul E. McKenney --- drivers/cpufreq/cpufreq_stats.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c index d37568c..10e6138 100644 --- a/drivers/cpufreq/cpufreq_stats.c +++ b/drivers/cpufreq/cpufreq_stats.c @@ -81,7 +81,7 @@ static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf) for (i = 0; i < stat->state_num; i++) { len += sprintf(buf + len, "%u %llu\n", stat->freq_table[i], (unsigned long long) - cputime64_to_clock_t(stat->time_in_state[i])); + jiffies_64_to_clock_t(stat->time_in_state[i])); } return len; } -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/