From: Christoph Hellwig <hch@infradead.org>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>,
Miklos Szeredi <miklos@szeredi.hu>,
Bernd Schubert <bschubert@ddn.com>,
axboe@kernel.dk, io-uring@vger.kernel.org,
linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-xfs@vger.kernel.org, dsingh@ddn.com
Subject: Re: [PATCH 1/2] fs: add FMODE_DIO_PARALLEL_WRITE flag
Date: Sat, 15 Apr 2023 22:54:49 -0700 [thread overview]
Message-ID: <ZDuNqQgpHUw+gi9G@infradead.org> (raw)
In-Reply-To: <20230414153612.GB360881@frogsfrogsfrogs>
On Fri, Apr 14, 2023 at 08:36:12AM -0700, Darrick J. Wong wrote:
> IIUC uring wants to avoid the situation where someone sends 300 writes
> to the same file, all of which end up in background workers, and all of
> which then contend on exclusive i_rwsem. Hence it has some hashing
> scheme that executes io requests serially if they hash to the same value
> (which iirc is the inode number?) to prevent resource waste.
>
> This flag turns off that hashing behavior on the assumption that each of
> those 300 writes won't serialize on the other 299 writes, hence it's ok
> to start up 300 workers.
>
> (apologies for precoffee garbled response)
It might be useful if someone (Jens?) could clearly document the
assumptions for this flag.
next prev parent reply other threads:[~2023-04-16 5:54 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-07 17:20 [PATCHSET for-next 0/2] Flag file systems as supporting parallel dio writes Jens Axboe
2023-03-07 17:20 ` [PATCH 1/2] fs: add FMODE_DIO_PARALLEL_WRITE flag Jens Axboe
2023-04-12 13:40 ` Bernd Schubert
2023-04-12 13:43 ` Bernd Schubert
2023-04-13 7:40 ` Miklos Szeredi
2023-04-13 9:25 ` Bernd Schubert
2023-04-14 5:11 ` Christoph Hellwig
2023-04-14 15:36 ` Darrick J. Wong
2023-04-15 13:15 ` Jens Axboe
2023-04-18 12:42 ` Miklos Szeredi
2023-04-18 12:55 ` Bernd Schubert
2023-04-18 22:13 ` Dave Chinner
2023-04-19 1:28 ` Jens Axboe
2023-04-16 5:54 ` Christoph Hellwig [this message]
2023-04-19 1:29 ` Jens Axboe
2023-03-07 17:20 ` [PATCH 2/2] io_uring: avoid hashing O_DIRECT writes if the filesystem doesn't need it Jens Axboe
2023-03-15 17:40 ` [PATCHSET for-next 0/2] Flag file systems as supporting parallel dio writes Jens Axboe
2023-03-16 4:29 ` Darrick J. Wong
2023-03-17 2:53 ` Jens Axboe
2023-04-03 12:24 ` Christian Brauner
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