From: Peter Zijlstra <peterz@infradead.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
linux-pm@vger.kernel.org, daniel.lezcano@linaro.org
Subject: Re: [PATCH 4/4] sched/core: split iowait state into two states
Date: Wed, 24 Apr 2024 12:01:27 +0200 [thread overview]
Message-ID: <20240424100127.GV40213@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20240416121526.67022-5-axboe@kernel.dk>
On Tue, Apr 16, 2024 at 06:11:21AM -0600, Jens Axboe wrote:
> iowait is a bogus metric, but it's helpful in the sense that it allows
> short waits to not enter sleep states that have a higher exit latency
> than would've otherwise have been picked for iowait'ing tasks. However,
> it's harmless in that lots of applications and monitoring assumes that
> iowait is busy time, or otherwise use it as a health metric.
> Particularly for async IO it's entirely nonsensical.
Let me get this straight, all of this is about working around
cpuidle menu governor insaity?
Rafael, how far along are we with fully deprecating that thing? Yes it
still exists, but should people really be using it still?
next prev parent reply other threads:[~2024-04-24 10:01 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-16 12:11 [PATCHSET v4 0/4] Split iowait into two states Jens Axboe
2024-04-16 12:11 ` [PATCH 1/4] sched/core: add helpers for iowait handling Jens Axboe
2024-04-16 12:11 ` [PATCH 2/4] sched/core: change rq->nr_iowait type to atomic_long_t on 64-bit Jens Axboe
2024-04-24 9:56 ` Peter Zijlstra
2024-04-16 12:11 ` [PATCH 3/4] sched/core: have io_schedule_prepare() return a long Jens Axboe
2024-04-16 12:11 ` [PATCH 4/4] sched/core: split iowait state into two states Jens Axboe
2024-04-16 14:10 ` Christian Loehle
2024-04-16 14:25 ` Christian Loehle
2024-04-24 10:01 ` Peter Zijlstra [this message]
2024-04-24 10:08 ` Christian Loehle
2024-04-25 10:16 ` Peter Zijlstra
2024-04-25 10:39 ` Christian Loehle
2024-04-25 14:20 ` Rafael J. Wysocki
-- strict thread matches above, loose matches on Subject: below --
2024-08-17 20:45 [PATCHSET v5 0/4] Split iowait " Jens Axboe
2024-08-17 20:45 ` [PATCH 4/4] sched/core: split iowait state " Jens Axboe
2024-08-19 15:39 [PATCHSET v6 0/4] Split iowait " Jens Axboe
2024-08-19 15:39 ` [PATCH 4/4] sched/core: split iowait state " Jens Axboe
2024-09-05 10:55 ` Peter Zijlstra
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