From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Ankur Arora <ankur.a.arora@oracle.com>
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
tglx@linutronix.de, paulmck@kernel.org, mingo@kernel.org,
juri.lelli@redhat.com, vincent.guittot@linaro.org,
dietmar.eggemann@arm.com, rostedt@goodmis.org,
bsegall@google.com, mgorman@suse.de, vschneid@redhat.com,
frederic@kernel.org, efault@gmx.de, sshegde@linux.ibm.com,
boris.ostrovsky@oracle.com, Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH v2 6/6] sched: warn for high latency with TIF_NEED_RESCHED_LAZY
Date: Thu, 14 Nov 2024 10:16:14 +0100 [thread overview]
Message-ID: <20241114091614.jSmSI78r@linutronix.de> (raw)
In-Reply-To: <20241106201758.428310-7-ankur.a.arora@oracle.com>
On 2024-11-06 12:17:58 [-0800], Ankur Arora wrote:
> Add support for warning if the TIF_NEED_RESCHED_LAZY bit is set
> without rescheduling for more than the latency_warn_ms period.
You fail to explain _why_ it is required to also check
TIF_NEED_RESCHED_LAZY to not be set.
The problem with NEED_RESCHED set but no scheduling in 100ms is a long
preempt-off or IRQ-off region .
The problem with NEED_RESCHED_LAZY set but no scheduling in 100ms is a
missing timer tick in that time. Also the previous mentioned things
might have happen.
And the code acting on NEED_RESCHED_LAZY is invoked before this check
is.
Sebastian
next prev parent reply other threads:[~2024-11-14 9:16 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-06 20:17 [PATCH v2 0/6] RCU changes for PREEMPT_LAZY Ankur Arora
2024-11-06 20:17 ` [PATCH v2 1/6] rcu: fix header guard for rcu_all_qs() Ankur Arora
2024-11-13 14:50 ` Frederic Weisbecker
2024-11-14 7:06 ` Sebastian Andrzej Siewior
2024-11-15 4:55 ` Ankur Arora
2024-11-06 20:17 ` [PATCH v2 2/6] rcu: rename PREEMPT_AUTO to PREEMPT_LAZY Ankur Arora
2024-11-13 14:59 ` Frederic Weisbecker
2024-11-13 23:51 ` Ankur Arora
2024-11-14 7:07 ` Sebastian Andrzej Siewior
2024-11-06 20:17 ` [PATCH v2 3/6] rcu: limit PREEMPT_RCU configurations Ankur Arora
2024-11-13 15:31 ` Frederic Weisbecker
2024-11-14 0:23 ` Ankur Arora
2024-11-14 8:25 ` Sebastian Andrzej Siewior
2024-11-14 11:36 ` Frederic Weisbecker
2024-11-25 21:40 ` Ankur Arora
2024-11-26 14:49 ` Frederic Weisbecker
2024-11-27 5:35 ` Ankur Arora
2024-11-27 6:19 ` Ankur Arora
2024-11-28 12:33 ` Frederic Weisbecker
2024-11-29 4:39 ` Ankur Arora
2024-11-29 12:49 ` Frederic Weisbecker
2024-11-06 20:17 ` [PATCH v2 4/6] rcu: handle quiescent states for PREEMPT_RCU=n, PREEMPT_COUNT=y Ankur Arora
2024-11-14 8:50 ` Sebastian Andrzej Siewior
2024-11-15 4:58 ` Ankur Arora
2024-11-28 13:36 ` Frederic Weisbecker
2024-11-06 20:17 ` [PATCH v2 5/6] osnoise: handle quiescent states for PREEMPT_RCU=n, PREEMPTION=y Ankur Arora
2024-11-14 9:22 ` Sebastian Andrzej Siewior
2024-11-15 4:59 ` Ankur Arora
2024-11-28 14:33 ` Frederic Weisbecker
2024-11-29 5:03 ` Ankur Arora
2024-11-29 14:22 ` Frederic Weisbecker
2024-11-29 19:21 ` Ankur Arora
2024-11-06 20:17 ` [PATCH v2 6/6] sched: warn for high latency with TIF_NEED_RESCHED_LAZY Ankur Arora
2024-11-14 9:16 ` Sebastian Andrzej Siewior [this message]
2024-11-14 10:01 ` [PATCH v2 0/6] RCU changes for PREEMPT_LAZY Sebastian Andrzej Siewior
2024-11-15 5:20 ` Ankur Arora
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