linux-fsdevel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Jan Kara <jack@suse.cz>
To: "yukuai (C)" <yukuai3@huawei.com>
Cc: Jan Kara <jack@suse.cz>,
	hch@infradead.org, darrick.wong@oracle.com,
	linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, houtao1@huawei.com,
	zhengbin13@huawei.com, yi.zhang@huawei.com
Subject: Re: [RFC] iomap: fix race between readahead and direct write
Date: Mon, 20 Jan 2020 12:42:07 +0100	[thread overview]
Message-ID: <20200120114207.GE19861@quack2.suse.cz> (raw)
In-Reply-To: <976d09e1-e3b5-a6a6-d159-9bdac3a7dc84@huawei.com>

On Sun 19-01-20 09:17:00, yukuai (C) wrote:
> 
> 
> On 2020/1/17 19:05, Jan Kara wrote:
> > provide
> > allocation for each page separately
> 
> Thank you for your response!
> 
> I do understand there will be additional CPU overhead. But page is allocated
> in __do_page_cache_readahead(), which is called before
> iomap_begin(). And I did not change that.

Sorry, I didn't express myself clearly. In "...one of the big points of iomap
infrastructure is that you call filesystem once to give you large extent
instead of calling it to provide allocation for each page separately." I
meant that with your patch, you call into filesystem to provide "block
allocation information" for each page separately. And it seems we both
agree this is going to cause additional CPU usage in the common case to
improve mostly unsupported corner case.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

  reply	other threads:[~2020-01-20 11:42 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16  6:36 [RFC] iomap: fix race between readahead and direct write yu kuai
2020-01-16 15:32 ` Jan Kara
2020-01-17  9:39   ` yukuai (C)
2020-01-17 11:05     ` Jan Kara
2020-01-17 16:24       ` Darrick J. Wong
2020-01-19  1:25         ` yukuai (C)
2020-01-19  1:17       ` yukuai (C)
2020-01-20 11:42         ` Jan Kara [this message]
2020-01-18 23:08 ` Matthew Wilcox
2020-01-19  1:34   ` yukuai (C)
2020-01-19  1:42     ` Matthew Wilcox
2020-01-19  1:57       ` yukuai (C)
2020-01-19  2:51       ` yukuai (C)
2020-01-19  3:01         ` Gao Xiang
2020-01-19  3:15           ` yukuai (C)
2020-01-19  6:14         ` Matthew Wilcox
2020-01-19  6:55           ` yukuai (C)
2020-01-19  7:58             ` Matthew Wilcox
2020-01-19 11:21               ` yukuai (C)

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200120114207.GE19861@quack2.suse.cz \
    --to=jack@suse.cz \
    --cc=darrick.wong@oracle.com \
    --cc=hch@infradead.org \
    --cc=houtao1@huawei.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-xfs@vger.kernel.org \
    --cc=yi.zhang@huawei.com \
    --cc=yukuai3@huawei.com \
    --cc=zhengbin13@huawei.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).