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From: Christoph Hellwig <hch@infradead.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk,
	akpm@linux-foundation.org
Subject: Re: [PATCHSET 0/3] Submit ->readpages() IO as read-ahead
Date: Fri, 25 May 2018 01:32:11 -0700	[thread overview]
Message-ID: <20180525083211.GA25442@infradead.org> (raw)
In-Reply-To: <1527177774-21414-1-git-send-email-axboe@kernel.dk>

On Thu, May 24, 2018 at 10:02:51AM -0600, Jens Axboe wrote:
> The only caller of ->readpages() is from read-ahead, yet we don't
> submit IO flagged with REQ_RAHEAD. This means we don't see it in
> blktrace, for instance, which is a shame. We already make assumptions
> about ->readpages() just being for read-ahead in the mpage
> implementation, using readahead_gfp_mask(mapping) as out GFP mask of
> choice.
> 
> This small series fixes up mpage_readpages() to submit with
> REQ_RAHEAD, which takes care of file systems using mpage_readpages().
> The last two fixup ext4 and btrfs.

What are the benefits?  Any setup where this buys us anything?  Any
setup where this actually regressed because drivers/hardware are
doing stupid things with REQ_RAHEAD?

  parent reply	other threads:[~2018-05-25  8:32 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-24 16:02 [PATCHSET 0/3] Submit ->readpages() IO as read-ahead Jens Axboe
2018-05-24 16:02 ` [PATCH 1/3] mpage: mpage_readpages() should submit " Jens Axboe
2018-05-24 19:43   ` Andrew Morton
2018-05-24 19:57     ` Matthew Wilcox
2018-05-24 20:24       ` Jens Axboe
2018-05-29 14:36     ` Jens Axboe
2018-05-29 21:59       ` Andrew Morton
2018-05-29 22:18         ` Jens Axboe
2018-05-29 22:37           ` Jens Axboe
2018-05-24 16:02 ` [PATCH 2/3] btrfs: readpages() " Jens Axboe
2018-05-24 16:02 ` [PATCH 3/3] ext4: " Jens Axboe
2018-05-24 20:47   ` Theodore Y. Ts'o
2018-05-24 20:53     ` Jens Axboe
2018-05-24 21:05       ` Jens Axboe
2018-05-25  8:32 ` Christoph Hellwig [this message]
2018-05-25 14:21   ` [PATCHSET 0/3] Submit ->readpages() " Jens Axboe

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