From: Ming Lei <ming.lei@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-kernel@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH] fs/buffer: try to submit writeback bio in unit of page
Date: Mon, 4 Jan 2021 17:24:25 +0800 [thread overview]
Message-ID: <20210104092425.GA3587310@T590> (raw)
In-Reply-To: <20210104084415.GA28741@lst.de>
On Mon, Jan 04, 2021 at 09:44:15AM +0100, Christoph Hellwig wrote:
> On Wed, Dec 30, 2020 at 08:08:15AM +0800, Ming Lei wrote:
> > It is observed that __block_write_full_page() always submit bio with size of block size,
> > which is often 512 bytes.
> >
> > In case of sequential IO, or >=4k BS random/seq writeback IO, most of times IO
> > represented by all buffer_head in each page can be done in single bio. It is actually
> > done in single request IO by block layer's plug merge too.
> >
> > So check if IO represented by buffer_head can be merged to single page
> > IO, if yes, just submit single bio instead of submitting one bio for each buffer_head.
>
> There is some very weird formatting in here. From a very quick look
> the changes look sensible, but I wonder if we should spend so much
> time optimizing the legacy buffer_head I/O path, rather than switching
> callers to saner helpers.
It may take long to convert fs code into iomap, and I understand fs/block_dev.c
can't be converted to iomap until all FS removes buffer_head, correct me
if it is wrong.
Thanks,
Ming
prev parent reply other threads:[~2021-01-04 9:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-30 0:08 [PATCH] fs/buffer: try to submit writeback bio in unit of page Ming Lei
2021-01-04 8:44 ` Christoph Hellwig
2021-01-04 9:24 ` Ming Lei [this message]
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