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From: Eric Sandeen <sandeen@redhat.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: cmm@us.ibm.com, tytso@mit.edu, linux-ext4@vger.kernel.org
Subject: Re: [PATCH] ext4: Don't allow lg prealloc list to be grow large.
Date: Mon, 21 Jul 2008 14:37:19 -0500	[thread overview]
Message-ID: <4884E56F.3010007@redhat.com> (raw)
In-Reply-To: <1216633234-24194-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>

Aneesh Kumar K.V wrote:
> The locality group prealloc list is freed only when there is a block allocation
> failure. This can result in large number of per cpu locality group prealloc space
> and also make the ext4_mb_use_preallocated expensive. Add a tunable max_lg_prealloc
> which default to 1000. If we have more than 1000 Per-CPU prealloc space and if we
> fail to find a suitable prealloc space during allocation we will now free all
> the prealloc space in the locality group.

It looks like this helps, but does not fare as well as the "perfectly
tuned" default (where the prealloc size is a multiple of the 20k/5 block
file size used in the test.)

I've added a plot of a delalloc run with your patch to the graph at:

http://people.redhat.com/esandeen/ext4/fs_mark.png

-Eric



  parent reply	other threads:[~2008-07-21 19:37 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-07-21  9:40 [PATCH] ext4: Don't allow lg prealloc list to be grow large Aneesh Kumar K.V
2008-07-21  9:40 ` [PATCH] ext4: Improve error handling in mballoc Aneesh Kumar K.V
2008-07-21 19:37 ` Eric Sandeen [this message]
  -- strict thread matches above, loose matches on Subject: below --
2008-07-22 11:10 [PATCH] ext4: Don't allow lg prealloc list to be grow large Aneesh Kumar K.V
2008-07-22 12:36 ` Aneesh Kumar K.V
2008-07-22 17:42 ` Eric Sandeen
2008-07-23 17:10 Patches for patchqueue Aneesh Kumar K.V
2008-07-23 17:10 ` [PATCH] ext4: Improve error handling in mballoc Aneesh Kumar K.V
2008-07-23 17:10   ` [PATCH] ext4: Convert the usage of NR_CPUS to nr_cpu_ids Aneesh Kumar K.V
2008-07-23 17:10     ` [PATCH] ext4: Don't allow lg prealloc list to be grow large Aneesh Kumar K.V
2008-07-23 18:13       ` Theodore Tso

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