From: Thavatchai Makphaibulchoke <thavatchai.makpahibulchoke@hp.com>
To: Andreas Dilger <adilger@dilger.ca>
Cc: T Makphaibulchoke <tmac@hp.com>, Theodore Ts'o <tytso@mit.edu>,
Al Viro <viro@zeniv.linux.org.uk>,
"linux-ext4@vger.kernel.org List" <linux-ext4@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org Devel"
<linux-fsdevel@vger.kernel.org>,
aswin@hp.com, Linus Torvalds <torvalds@linux-foundation.org>,
aswin_proj@groups.hp.com
Subject: Re: [PATCH v3 0/2] ext4: increase mbcache scalability
Date: Wed, 04 Sep 2013 15:33:50 +0000 [thread overview]
Message-ID: <522752DE.7090308@hp.com> (raw)
In-Reply-To: <FDD6EB21-7C40-4F4D-904C-8514535CC7C3@dilger.ca>
On 09/04/2013 08:00 PM, Andreas Dilger wrote:
>
> In the past, I've raised the question of whether mbcache is even
> useful on real-world systems. Essentially, this is providing a
> "deduplication" service for ext2/3/4 xattr blocks that are identical.
> The question is how often this is actually the case in modern use?
> The original design was for allowing external ACL blocks to be
> shared between inodes, at a time when ACLs where pretty much the
> only xattrs stored on inodes.
>
> The question now is whether there are common uses where all of the
> xattrs stored on multiple inodes are identical? If that is not the
> case, mbcache is just adding overhead and should just be disabled
> entirely instead of just adding less overhead.
>
> There aren't good statistics on the hit rate for mbcache, but it
> might be possible to generate some with systemtap or similar to
> see how often ext4_xattr_cache_find() returns NULL vs. non-NULL.
>
> Cheers, Andreas
>
Thanks Andreas for the comments. Since I'm not familiar with systemtap, I'm thinking probably the quickest and simplest way is to re-run aim7 and swing bench with mbcache disabled for comparison. Please let me know if you have any other benchmark suggestion or if you think systemtap on ext4_xattr_cache_find() would give a more accurate measurement.
Thanks,
Mak.
next prev parent reply other threads:[~2013-09-04 15:33 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-18 0:55 [PATCH 0/2] ext4: increase mbcache scalability T Makphaibulchoke
2013-08-22 15:54 ` [PATCH v2 " T Makphaibulchoke
2013-08-22 15:54 ` [PATCH v2 1/2] mbcache: decoupling the locking of local from global data T Makphaibulchoke
2013-08-22 16:53 ` Linus Torvalds
2013-08-22 15:33 ` Thavatchai Makphaibulchoke
2013-08-22 15:54 ` [PATCH v2 2/2] ext4: each filesystem creates and uses its own mc_cache T Makphaibulchoke
2014-01-24 18:31 ` [PATCH v4 0/3] ext4: increase mbcache scalability T Makphaibulchoke
2014-01-24 18:31 ` [PATCH v4 1/3] fs/mbcache.c change block and index hash chain to hlist_bl_node T Makphaibulchoke
2014-01-24 18:31 ` [PATCH v4 2/3] mbcache: decoupling the locking of local from global data T Makphaibulchoke
2014-01-24 18:31 ` [PATCH v4 3/3] ext4: each filesystem creates and uses its own mc_cache T Makphaibulchoke
2014-01-24 21:38 ` [PATCH v4 0/3] ext4: increase mbcache scalability Andi Kleen
2014-01-25 1:13 ` Thavatchai Makphaibulchoke
2014-01-25 6:09 ` Andreas Dilger
2014-01-27 12:27 ` Thavatchai Makphaibulchoke
2014-02-09 19:46 ` Thavatchai Makphaibulchoke
2014-02-11 19:58 ` Thavatchai Makphaibulchoke
2014-02-13 2:01 ` Andreas Dilger
2013-09-04 16:39 ` [PATCH v3 0/2] " T Makphaibulchoke
2013-09-04 16:39 ` [PATCH v3 1/2] mbcache: decoupling the locking of local from global data T Makphaibulchoke
2013-10-30 13:27 ` Theodore Ts'o
2013-10-30 14:42 ` Theodore Ts'o
2013-10-30 17:32 ` Thavatchai Makphaibulchoke
2013-09-04 16:39 ` [PATCH v3 2/2] ext4: each filesystem creates and uses its own mb_cache T Makphaibulchoke
2013-10-30 14:30 ` Theodore Ts'o
2013-09-04 20:00 ` [PATCH v3 0/2] ext4: increase mbcache scalability Andreas Dilger
2013-09-04 15:33 ` Thavatchai Makphaibulchoke [this message]
2013-09-05 15:22 ` Thavatchai Makphaibulchoke
2013-09-05 2:35 ` Theodore Ts'o
2013-09-05 9:49 ` Thavatchai Makphaibulchoke
2013-09-06 5:10 ` Andreas Dilger
2013-09-06 12:23 ` Thavatchai Makphaibulchoke
2013-09-10 20:47 ` Andreas Dilger
2013-09-10 21:02 ` Theodore Ts'o
2013-09-10 17:10 ` Thavatchai Makphaibulchoke
2013-09-11 3:13 ` Eric Sandeen
2013-09-11 11:30 ` Theodore Ts'o
2013-09-11 16:49 ` Eric Sandeen
2013-09-11 19:33 ` Eric Sandeen
2013-09-11 20:32 ` David Lang
2013-09-11 20:48 ` Eric Sandeen
2013-09-11 21:25 ` Theodore Ts'o
2013-09-11 20:36 ` Thavatchai Makphaibulchoke
2013-09-12 3:42 ` Eric Sandeen
2014-02-20 18:37 ` [PATCH V5 0/3] " T Makphaibulchoke
2014-02-20 18:37 ` [PATCH V5 1/3] fs/mbcache.c change block and index hash chain to hlist_bl_node T Makphaibulchoke
2014-02-20 18:37 ` [PATCH V5 2/3] mbcache: decoupling the locking of local from global data T Makphaibulchoke
2014-02-20 18:37 ` [PATCH V5 3/3] ext4: each filesystem creates and uses its own mb_cache T Makphaibulchoke
2014-03-12 16:19 ` [PATCH v5 RESEND 0/3] ext4: increase mbcache scalability T Makphaibulchoke
2014-03-12 16:19 ` [PATCH v5 RESEND 1/3] fs/mbcache.c change block and index hash chain to hlist_bl_node T Makphaibulchoke
2014-03-12 16:19 ` [PATCH v5 RESEND 2/3] mbcache: decoupling the locking of local from global data T Makphaibulchoke
2014-03-12 16:19 ` [PATCH v5 RESEND 3/3] ext4: each filesystem creates and uses its own mb_cache T Makphaibulchoke
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