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From: Theodore Ts'o <tytso@mit.edu>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: linux-ext4@vger.kernel.org
Subject: Re: [PATCH 5/6] libext2fs/e2fsck: provide routines to read-ahead metadata
Date: Mon, 11 Aug 2014 14:32:58 -0400	[thread overview]
Message-ID: <20140811183258.GF6553@thunk.org> (raw)
In-Reply-To: <20140811180509.GE2808@birch.djwong.org>

On Mon, Aug 11, 2014 at 11:05:09AM -0700, Darrick J. Wong wrote:
> 
> Using the bitmap turns out to be pretty quick (~130us to start RA for 4 groups
> vs. ~70us per group if I issue the RA directly).  Each fadvise call seems to
> cost us ~1ms, so I'll keep using the bitmap to minimize the number of fadvise
> calls, since it's also a lot less code.

4 groups?  Since the default flex_bg size is 16 block groups, I would
have expected that you would want to start RA every 16 groups.

(And BTW, I've been wondering whether we should increase the flex_bg
size for bigger file systems.  By the time we get to 4TB disks, Having
a flex_bg every 2GB seems a little small.)

						- Ted

  reply	other threads:[~2014-08-11 18:33 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-08-09  4:26 [PATCH 0/6] e2fsprogs Summer 2014 patchbomb, part 5 Darrick J. Wong
2014-08-09  4:26 ` [PATCH 1/6] libext2fs: create inlinedata symlinks Darrick J. Wong
2014-08-24 16:15   ` Theodore Ts'o
2014-08-09  4:26 ` [PATCH 2/6] misc: fix gcc warnings Darrick J. Wong
2014-08-24 16:24   ` Theodore Ts'o
2014-08-09  4:26 ` [PATCH 3/6] mke2fs: set block_validity as a default mount option Darrick J. Wong
2014-08-24 22:47   ` Theodore Ts'o
2014-08-25 15:52     ` Darrick J. Wong
2014-08-25 16:36       ` [PATCH] ext4: enable block_validity by default Darrick J. Wong
2014-09-02  2:02         ` Theodore Ts'o
2014-08-09  4:26 ` [PATCH 4/6] ext2fs: add readahead method to improve scanning Darrick J. Wong
2014-08-09  4:26 ` [PATCH 5/6] libext2fs/e2fsck: provide routines to read-ahead metadata Darrick J. Wong
2014-08-11  5:21   ` Darrick J. Wong
2014-08-11  6:24     ` Theodore Ts'o
2014-08-11  6:31       ` Darrick J. Wong
2014-08-11 14:34         ` Theodore Ts'o
2014-08-11 18:05           ` Darrick J. Wong
2014-08-11 18:32             ` Theodore Ts'o [this message]
2014-08-11 18:55               ` Darrick J. Wong
2014-08-11 20:10                 ` Theodore Ts'o
2014-08-11 20:50                   ` Darrick J. Wong
2014-08-09  4:26 ` [PATCH 6/6] e2fsck: read-ahead metadata during passes 1, 2, and 4 Darrick J. Wong
2014-08-09  5:53 ` [PATCH 0/6] e2fsprogs Summer 2014 patchbomb, part 5 Theodore Ts'o
2014-08-09  5:59   ` Darrick J. Wong

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