From: Dave Chinner <dgc@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Tal Zussman <tz2294@columbia.edu>, Jens Axboe <axboe@kernel.dk>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Christian Brauner <brauner@kernel.org>,
"Darrick J. Wong" <djwong@kernel.org>,
Carlos Maiolino <cem@kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz>,
Bart Van Assche <bvanassche@acm.org>,
Gao Xiang <hsiangkao@linux.alibaba.com>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH 8/8] RFC: use a TASK_FIFO kthread for read completion support
Date: Sat, 11 Apr 2026 08:11:22 +1000 [thread overview]
Message-ID: <adl1iqhldFvJwSw-@dread> (raw)
In-Reply-To: <20260409160243.1008358-9-hch@lst.de>
On Thu, Apr 09, 2026 at 06:02:21PM +0200, Christoph Hellwig wrote:
> Commit 3fffb589b9a6 ("erofs: add per-cpu threads for decompression as an
> option") explains why workqueue aren't great for low-latency completion
> handling. Switch to a per-cpu kthread to handle it instead. This code
> is based on the erofs code in the above commit, but further simplified
> by directly using a kthread instead of a kthread_work.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
Can we please not go back to the (bad) old days of individual
subsystems needing their own set of per-cpu kernel tasks just
sitting around idle most of of the time? The whole point of the
workqueue infrastructure was to get rid of this widely repeated
anti-pattern.
If there's a latency problem with workqueue scheduling, then we
should be fixing that problem rather than working around it in every
subsystem that thinkgs it has a workqueue scheduling latency
issue...
-Dave.
--
Dave Chinner
dgc@kernel.org
next prev parent reply other threads:[~2026-04-10 22:11 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-09 16:02 bio completion in task enhancements / experiments Christoph Hellwig
2026-04-09 16:02 ` [PATCH 1/8] block: add BIO_COMPLETE_IN_TASK for task-context completion Christoph Hellwig
2026-04-09 16:02 ` [PATCH 2/8] iomap: use BIO_COMPLETE_IN_TASK for dropbehind writeback Christoph Hellwig
2026-04-09 16:02 ` [PATCH 3/8] block: enable RWF_DONTCACHE for block devices Christoph Hellwig
2026-04-09 16:02 ` [PATCH 4/8] FOLD: block: change the defer in task context interface to be procedural Christoph Hellwig
2026-04-09 20:18 ` Matthew Wilcox
2026-04-10 6:17 ` Christoph Hellwig
2026-04-10 13:26 ` Matthew Wilcox
2026-04-15 5:44 ` Christoph Hellwig
2026-04-15 14:30 ` Matthew Wilcox
2026-04-09 16:02 ` [PATCH 5/8] FOLD: don't use in_task() to decide for offloading Christoph Hellwig
2026-04-09 16:02 ` [PATCH 6/8] iomap: use bio_complete_in_task for buffered read errors Christoph Hellwig
2026-05-14 18:30 ` Tal Zussman
2026-04-09 16:02 ` [PATCH 7/8] iomap: use bio_complete_in_task for buffered write completions Christoph Hellwig
2026-04-09 16:02 ` [PATCH 8/8] RFC: use a TASK_FIFO kthread for read completion support Christoph Hellwig
2026-04-09 19:06 ` Tal Zussman
2026-04-10 6:19 ` Christoph Hellwig
2026-04-10 22:11 ` Dave Chinner [this message]
2026-04-10 23:44 ` Gao Xiang
2026-04-10 23:53 ` Gao Xiang
2026-04-14 0:58 ` Dave Chinner
2026-04-14 2:23 ` Gao Xiang
2026-04-15 5:55 ` Christoph Hellwig
2026-04-15 6:05 ` Gao Xiang
2026-04-15 6:30 ` Sebastian Andrzej Siewior
2026-04-15 6:59 ` Christoph Hellwig
2026-04-15 12:49 ` Sandeep Dhavale
2026-04-15 8:28 ` David Laight
2026-04-15 5:48 ` Christoph Hellwig
2026-04-15 5:50 ` Christoph Hellwig
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