From: Hugo Mills <hugo@carfax.org.uk>
To: lilofile <lilofile@aliyun.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: question
Date: Sun, 20 Oct 2013 17:53:36 +0100 [thread overview]
Message-ID: <20131020165336.GD6598@carfax.org.uk> (raw)
In-Reply-To: <1c7f1ff8-7161-4e67-9acc-eb5d4b8b965d@aliyun.com>
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On Sun, Oct 20, 2013 at 11:19:26PM +0800, lilofile wrote:
>
> when i read transaction_kthread function in disk-io.c
>
> delay = HZ * 30;
>
> why commit transaction is 30 seconds, Other values 20 seconds,10 seconds?
> what considerations about the commit transaction interval?
It's a more or less arbitrary number. There's been a patch recently
(last couple of months) to allow modifying the value. If you make it
too large, you end up using lots of RAM for unflushed changes, you
risk losing those changes if the machine crashes. If you make it too
small, you end up writing lots more metadata, because that's always
changing as the FS is modified.
Hugo.
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next prev parent reply other threads:[~2013-10-20 16:53 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-20 15:19 question lilofile
2013-10-20 16:53 ` Hugo Mills [this message]
-- strict thread matches above, loose matches on Subject: below --
2008-08-12 20:06 Question Morey Roof
2008-08-12 20:32 ` Question Jeff Schroeder
2008-08-13 13:19 ` Question Chris Mason
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