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

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Date: Thu, 25 Jan 2024 08:58:08 -0000
From: "tip-bot2 for Tim Chen" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Tim Chen <tim.c.chen@...ux.intel.com>,
 Thomas Gleixner <tglx@...utronix.de>, stable@...r.kernel.org, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: timers/urgent] tick/sched: Preserve number of idle sleeps
 across CPU hotplug events

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@...ux.intel.com>
AuthorDate:    Mon, 22 Jan 2024 15:35:34 -08:00
Committer:     Thomas Gleixner <tglx@...utronix.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@...ux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: stable@...r.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