From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir@xensource.com>
Subject: Re: [PATCH][TOOLS] Reducing impact
	ofdomainsave/restore/dump on Dom0
Date: Wed, 21 Feb 2007 15:10:21 +0000
Message-ID: <C202115D.9DAA%keir@xensource.com>
References: <342BAC0A5467384983B586A6B0B3767104BE068C@EXNA.corp.stratus.com>
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To: "Graham, Simon" <Simon.Graham@stratus.com>, Keir Fraser <keir@xensource.com>, xen-devel@lists.xensource.com
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On 21/2/07 15:06, "Graham, Simon" <Simon.Graham@stratus.com> wrote:

> 2. sync-then-advise is only done at the end of writing a file to ensure
> that all
>    of the cached pages are discarded. Whilst writing the file, I only
> fadvise
>    which triggers a write back and discards any clean pages up to the
> specified offset.
>    This is indeed a performance thing -- fsyncing on every write makes
> it very slow.

Do you need the fsync at all? It's possible that the kernel will
launder-then-discard the affected pages automatically, just from the
fadvise() alone.

 -- Keir