[PATCH] tick-sched: Preserve number of idle sleeps across CPU hotplug events

[PATCH] tick-sched: Preserve number of idle sleeps across CPU hotplug events

[Tim Chen]

Patch 71fee48f ("tick-sched: Fix idle and iowait sleeptime accounting vs
CPU hotplug") preserved total idle sleep time and iowait sleeptime
across CPU hotplug events.

In order to derive average sleep time per sleep event, we should also
preserve number of sleeps too in idle_calls and idle_sleeps. Fix that.

Fixes: 71fee48f ("tick-sched: Fix idle and iowait sleeptime accounting vs CPU hotplug")
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
---
 kernel/time/tick-sched.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index d2501673028d..01fb50c1b17e 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -1577,6 +1577,7 @@ void tick_cancel_sched_timer(int cpu)
 {
 	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
 	ktime_t idle_sleeptime, iowait_sleeptime;
+	unsigned long idle_calls, idle_sleeps;
 
 # ifdef CONFIG_HIGH_RES_TIMERS
 	if (ts->sched_timer.base)
@@ -1585,9 +1586,13 @@ void tick_cancel_sched_timer(int cpu)
 
 	idle_sleeptime = ts->idle_sleeptime;
 	iowait_sleeptime = ts->iowait_sleeptime;
+	idle_calls = ts->idle_calls;
+	idle_sleeps = ts->idle_sleeps;
 	memset(ts, 0, sizeof(*ts));
 	ts->idle_sleeptime = idle_sleeptime;
 	ts->iowait_sleeptime = iowait_sleeptime;
+	ts->idle_calls = idle_calls;
+	ts->idle_sleeps = idle_sleeps;
 }
 #endif
 
-- 
2.32.0

Re: [PATCH] tick-sched: Preserve number of idle sleeps across CPU hotplug events

[Thomas Gleixner]

On Mon, Jan 22 2024 at 15:35, Tim Chen wrote:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=71fee48fb772ac4f6cfa63dbebc5629de8b4cc09

Re: [PATCH] tick-sched: Preserve number of idle sleeps across CPU hotplug events

[Frederic Weisbecker]

Le Wed, Jan 24, 2024 at 08:30:28PM +0100, Thomas Gleixner a écrit :
> On Mon, Jan 22 2024 at 15:35, Tim Chen wrote:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=71fee48fb772ac4f6cfa63dbebc5629de8b4cc09
> 

It's a different patch :-)

Re: [PATCH] tick-sched: Preserve number of idle sleeps across CPU hotplug events

[Thomas Gleixner]

On Wed, Jan 24 2024 at 21:11, Frederic Weisbecker wrote:

> Le Wed, Jan 24, 2024 at 08:30:28PM +0100, Thomas Gleixner a écrit :
>> On Mon, Jan 22 2024 at 15:35, Tim Chen wrote:
>> 
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=71fee48fb772ac4f6cfa63dbebc5629de8b4cc09
>> 
>
> It's a different patch :-)

I clearly can't read ....

[tip: timers/urgent] tick/sched: Preserve number of idle sleeps across CPU hotplug events

[tip-bot2 for Tim Chen]

The following commit has been merged into the timers/urgent branch of tip:

Commit-ID:     9a574ea9069be30b835a3da772c039993c43369b
Gitweb:        https://git.kernel.org/tip/9a574ea9069be30b835a3da772c039993c43369b
Author:        Tim Chen <tim.c.chen@linux.intel.com>
AuthorDate:    Mon, 22 Jan 2024 15:35:34 -08:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Thu, 25 Jan 2024 09:52:40 +01:00

tick/sched: Preserve number of idle sleeps across CPU hotplug events

Commit 71fee48f ("tick-sched: Fix idle and iowait sleeptime accounting vs
CPU hotplug") preserved total idle sleep time and iowait sleeptime across
CPU hotplug events.

Similar reasoning applies to the number of idle calls and idle sleeps to
get the proper average of sleep time per idle invocation.

Preserve those fields too.

Fixes: 71fee48f ("tick-sched: Fix idle and iowait sleeptime accounting vs CPU hotplug")
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240122233534.3094238-1-tim.c.chen@linux.intel.com
---
 kernel/time/tick-sched.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index d250167..01fb50c 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -1577,6 +1577,7 @@ void tick_cancel_sched_timer(int cpu)
 {
 	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
 	ktime_t idle_sleeptime, iowait_sleeptime;
+	unsigned long idle_calls, idle_sleeps;
 
 # ifdef CONFIG_HIGH_RES_TIMERS
 	if (ts->sched_timer.base)
@@ -1585,9 +1586,13 @@ void tick_cancel_sched_timer(int cpu)
 
 	idle_sleeptime = ts->idle_sleeptime;
 	iowait_sleeptime = ts->iowait_sleeptime;
+	idle_calls = ts->idle_calls;
+	idle_sleeps = ts->idle_sleeps;
 	memset(ts, 0, sizeof(*ts));
 	ts->idle_sleeptime = idle_sleeptime;
 	ts->iowait_sleeptime = iowait_sleeptime;
+	ts->idle_calls = idle_calls;
+	ts->idle_sleeps = idle_sleeps;
 }
 #endif