From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Keith Busch <kbusch@kernel.org>, Christoph Hellwig <hch@lst.de>,
ming.lei@redhat.com, linux-block@vger.kernel.org
Subject: Re: [PATCH] block: avoid blk_bio_segment_split for small I/O operations
Date: Mon, 4 Nov 2019 23:57:36 +0100 [thread overview]
Message-ID: <20191104225736.GA25569@lst.de> (raw)
In-Reply-To: <2822bfe1-5d9d-ec87-9607-36617e528985@kernel.dk>
On Mon, Nov 04, 2019 at 03:55:41PM -0700, Jens Axboe wrote:
> > All existing ones I'm aware of are 128k, so 4k aligned, but if the LBA
> > format is 512B, you could start a 4k IO at a 126k offset to straddle the
> > boundary. Hm, maybe we don't care about the split penalty in that case
> > since unaligned access is already going to be slower for other reasons ...
>
> Yeah, not sure that's a huge concern for that particular case. If you
> think it's a real world issue, it should be possible to set aside a
> queue bit for this and always have them hit the slower split path.
Well, we use that field for zoned devices also, in which case it is an
issue. I think I'll need to send a patch to skip the fast path if
we have chunk_sectors set.
next prev parent reply other threads:[~2019-11-04 22:57 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-04 18:05 [PATCH] block: avoid blk_bio_segment_split for small I/O operations Christoph Hellwig
2019-11-04 18:24 ` Jens Axboe
2019-11-04 19:30 ` Keith Busch
2019-11-04 20:13 ` Jens Axboe
2019-11-04 22:50 ` Keith Busch
2019-11-04 22:55 ` Jens Axboe
2019-11-04 22:57 ` Christoph Hellwig [this message]
2019-11-04 22:59 ` Jens Axboe
2019-11-04 22:58 ` Bart Van Assche
2019-11-04 23:04 ` Keith Busch
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