linux-kernel - [PATCH v2 3/8] sched: Update the idle statistics in get_cpu_idle_time

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20100509082323.2d2f1945@infradead.org>
Date:	Sun, 9 May 2010 08:23:23 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu, davej@...hat.com
Subject: [PATCH v2  3/8] sched: Update the idle statistics in
 get_cpu_idle_time_us()

From: Arjan van de Ven <arjan@...ux.intel.com>

Right now, get_cpu_idle_time_us() only reports the idle statistics
upto the point the CPU entered last idle; not what is valid right now.

This patch adds an update of the idle statistics to get_cpu_idle_time_us(),
so that calling this function always returns statistics that are accurate
at the point of the call.

This includes resetting the start of the idle time for accounting purposes
to avoid double accounting.

Signed-off-by: Arjan van de Ven <arjan@...ux.intel.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Reviewed-by: Rik van Riel <riel@...hat.com>
---

 kernel/time/tick-sched.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff -puN kernel/time/tick-sched.c~sched-update-the-idle-statistics-in-get_cpu_idle_time_us kernel/time/tick-sched.c
--- a/kernel/time/tick-sched.c~sched-update-the-idle-statistics-in-get_cpu_idle_time_us
+++ a/kernel/time/tick-sched.c
@@ -161,6 +161,7 @@ static void update_ts_time_stats(struct 
 	if (ts->idle_active) {
 		delta = ktime_sub(now, ts->idle_entrytime);
 		ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
+		ts->idle_entrytime = now;
 	}
 }
 
@@ -205,14 +206,18 @@ static ktime_t tick_nohz_start_idle(stru
 u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time)
 {
 	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
+	ktime_t now;
 
 	if (!tick_nohz_enabled)
 		return -1;
 
+	now = ktime_get();
+	update_ts_time_stats(ts, now);
+
 	if (ts->idle_active)
 		*last_update_time = ktime_to_us(ts->idle_lastupdate);
 	else
-		*last_update_time = ktime_to_us(ktime_get());
+		*last_update_time = ktime_to_us(now);
 
 	return ktime_to_us(ts->idle_sleeptime);
 }
_
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/