From: Peter Zijlstra <peterz@infradead.org>
To: Florian Schmaus <flo@geekplace.eu>
Cc: Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Valentin Schneider <vschneid@redhat.com>,
Kent Overstreet <kent.overstreet@linux.dev>,
linux-bcachefs@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] bcachefs: set rebalance thread to SCHED_BATCH and nice 19
Date: Tue, 14 Jan 2025 15:32:14 +0100 [thread overview]
Message-ID: <20250114143214.GT5388@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20250114130513.498482-4-flo@geekplace.eu>
On Tue, Jan 14, 2025 at 01:47:28PM +0100, Florian Schmaus wrote:
> While the rebalance thread is isually not compute bound, it does cause
> a considerable amount of I/O. Since "reducing" the nice level from 0
> to 19, also implicitly reduces the threads best-effort I/O scheduling
> class level from 4 to 7, the reblance thread's I/O will be depriotized
> over normal I/O.
>
> Furthermore, we set the rebalance thread's scheduling class to BATCH,
> which means that it will potentially receive a higher scheduling
> latency. Making room for threads that need a low
> schedulinglatency (e.g., interactive onces).
sorta.. what worries me most about these patches are the claims without
backing numbers.
Supposedly there is a problem, and this here fixes it, but it doesn't
really get quantified much here.
next prev parent reply other threads:[~2025-01-14 14:32 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-14 12:47 [RESEND] Add sched_set_batch() and run bcachefs-rebalance under SCHED_BATCH Florian Schmaus
2025-01-14 12:47 ` [PATCH 1/2] sched: provide sched_set_batch() Florian Schmaus
2025-01-14 12:47 ` [PATCH 2/2] bcachefs: set rebalance thread to SCHED_BATCH and nice 19 Florian Schmaus
2025-01-14 13:29 ` Christian Loehle
2025-01-14 14:40 ` Peter Zijlstra
2025-01-14 15:05 ` Christian Loehle
2025-01-14 15:32 ` Kent Overstreet
2025-01-14 15:19 ` Kent Overstreet
2025-01-14 16:45 ` Florian Schmaus
2025-01-14 14:32 ` Peter Zijlstra [this message]
2025-01-14 15:25 ` Kent Overstreet
2025-01-14 16:45 ` Florian Schmaus
[not found] <20241114210649.71377-1-flo@geekplace.eu>
2024-11-14 21:06 ` [PATCH 2/2] bcachefs: Set " Florian Schmaus
2024-11-15 5:43 ` Kent Overstreet
2024-11-15 8:26 ` Florian Schmaus
2024-11-15 20:42 ` Kent Overstreet
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