From: Shaohua Li <shaohua.li@intel.com>
To: Chris Mason <chris.mason@oracle.com>,
linux-btrfs@vger.kernel.org,
Arjan van de Ven <arjan@linux.intel.com>,
"Wu, Fengguang" <fengguang.wu@intel.com>
Subject: Re: [patch 1/2]btrfs: add an ioctl to dump metadata info
Date: Tue, 20 Jul 2010 08:37:30 +0800 [thread overview]
Message-ID: <20100720003730.GA14218@sli10-desk.sh.intel.com> (raw)
In-Reply-To: <20100719112705.GX8623@think>
On Mon, Jul 19, 2010 at 07:27:05PM +0800, Chris Mason wrote:
> On Wed, Jul 14, 2010 at 04:02:21PM +0800, Shaohua Li wrote:
> > Add an ioctl to dump btrfs btree_inode's existing pages. Userspace collects such
> > info and uses it to do metadata readahead.
>
> In your tests, how often is the mincore done on metadata? With cow
> (especially with cow and atime), the metadata blocks are going to change
> quite a lot.
Meego uses relatime. The proposal is doing mincore in every boot. In my test,
I delete several files and a dir, create a dir and several files, the hit rate
is > 80%, which is already pretty good for boot. In userspace, we record some
extra pages. For example, if mincore returns two pages 2 and 4, userspace will
record pages 2-4, in total 3 pages, this will slightly increase hit rate too.
Thanks,
Shaohua
prev parent reply other threads:[~2010-07-20 0:37 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-14 8:02 [patch 1/2]btrfs: add an ioctl to dump metadata info Shaohua Li
2010-07-19 11:27 ` Chris Mason
2010-07-20 0:37 ` Shaohua Li [this message]
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