From: Josef Bacik <jbacik@fb.com>
To: Miao Xie <miaox@cn.fujitsu.com>, <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH] Btrfs: improve the performance fluctuating of the fsync
Date: Wed, 18 Dec 2013 16:38:47 -0500 [thread overview]
Message-ID: <52B215E7.7000809@fb.com> (raw)
In-Reply-To: <1387363964-20316-1-git-send-email-miaox@cn.fujitsu.com>
On 12/18/2013 05:52 AM, Miao Xie wrote:
> In order to improve the performance of fsync, we use the outstanding
> ordered extents to avoid looking up the checksum from the csum tree.
> But we didn't filter out the ordered extents whose csum is still being
> calculated, when we got those ordered extents, we had to wait for the
> csum calculation. It made the performance dropped down suddenly. (On
> my box, it drop down from 56MB/s to 4-10MB/s)
>
> But actually, the csum calculation of the ordered extents which were
> introduced by the current fsync had already completed. Those ordered
> extents whose csum was being calculated didn't belong to the current
> fsync, we can ignore them.
This isn't true because we will just start IO and carry on and wait
later on, so we could very well have ordered extents that we started for
this fsync without their csums ready which is why this code exists. Thanks,
Josef
prev parent reply other threads:[~2013-12-18 21:38 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-18 10:52 [PATCH] Btrfs: improve the performance fluctuating of the fsync Miao Xie
2013-12-18 11:09 ` Leonidas Spyropoulos
2014-01-02 10:10 ` Sander
2013-12-18 21:38 ` Josef Bacik [this message]
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