[PATCH v2 30/35] sched: latency warn for TIF_NEED_RESCHED_LAZY

Ankur Arora
2024-05-28T00:37:14Z

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@redhat.com>
Cc: Peter Ziljstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.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 2bc3ae21a9d0..4f0ac90b7d47 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5673,7 +5673,7 @@ 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..a1be40101844 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(RESCHED_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