linux-kernel - [PATCH 27/30] sched: latency warn for TIF_NEED_RESCHED

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Date: Mon, 12 Feb 2024 21:55:51 -0800
From: Ankur Arora <ankur.a.arora@...cle.com>
To: linux-kernel@...r.kernel.org
Cc: tglx@...utronix.de, peterz@...radead.org, torvalds@...ux-foundation.org,
        paulmck@...nel.org, akpm@...ux-foundation.org, luto@...nel.org,
        bp@...en8.de, dave.hansen@...ux.intel.com, hpa@...or.com,
        mingo@...hat.com, juri.lelli@...hat.com, vincent.guittot@...aro.org,
        willy@...radead.org, mgorman@...e.de, jpoimboe@...nel.org,
        mark.rutland@....com, jgross@...e.com, andrew.cooper3@...rix.com,
        bristot@...nel.org, mathieu.desnoyers@...icios.com,
        geert@...ux-m68k.org, glaubitz@...sik.fu-berlin.de,
        anton.ivanov@...bridgegreys.com, mattst88@...il.com,
        krypton@...ich-teichert.org, rostedt@...dmis.org,
        David.Laight@...LAB.COM, richard@....at, mjguzik@...il.com,
        jon.grimm@....com, bharata@....com, raghavendra.kt@....com,
        boris.ostrovsky@...cle.com, konrad.wilk@...cle.com,
        Ankur Arora <ankur.a.arora@...cle.com>
Subject: [PATCH 27/30] sched: latency warn for TIF_NEED_RESCHED_LAZY

resched_latency_warn() now also warns if TIF_NEED_RESCHED_LAZY
is set without rescheduling for more than the latency_warn_ms period.

Cc: Ingo Molnar <mingo@...hat.com>
Cc: Peter Ziljstra <peterz@...radead.org>
Cc: Juri Lelli <juri.lelli@...hat.com>
Cc: Vincent Guittot <vincent.guittot@...aro.org>
Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>
---
 kernel/sched/core.c  | 2 +-
 kernel/sched/debug.c | 7 +++++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index aa31f23f43f4..cce84ba0417f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5670,7 +5670,7 @@ static u64 cpu_resched_latency(struct rq *rq)
 	if (sysctl_resched_latency_warn_once && warned_once)
 		return 0;
 
-	if (!need_resched() || !latency_warn_ms)
+	if ((!need_resched() && !need_resched_lazy()) || !latency_warn_ms)
 		return 0;
 
 	if (system_state == SYSTEM_BOOTING)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index e53f1b73bf4a..869a09781f2e 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -1114,9 +1114,12 @@ void proc_sched_set_task(struct task_struct *p)
 void resched_latency_warn(int cpu, u64 latency)
 {
 	static DEFINE_RATELIMIT_STATE(latency_check_ratelimit, 60 * 60 * HZ, 1);
+	char *nr;
+
+	nr = tif_need_resched(NR_now) ? "need_resched" : "need_resched_lazy";
 
 	WARN(__ratelimit(&latency_check_ratelimit),
-	     "sched: CPU %d need_resched set for > %llu ns (%d ticks) "
+	     "sched: CPU %d %s set for > %llu ns (%d ticks) "
 	     "without schedule\n",
-	     cpu, latency, cpu_rq(cpu)->ticks_without_resched);
+	     cpu, nr, latency, cpu_rq(cpu)->ticks_without_resched);
 }
-- 
2.31.1