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Re: [Xen-devel] [PATCH][TOOLS] Reducing impact ofdomainsave/restore/dump on Dom0

  • To: "Graham, Simon" <Simon.Graham@xxxxxxxxxxx>, Keir Fraser <keir@xxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: Keir Fraser <keir@xxxxxxxxxxxxx>
  • Date: Wed, 21 Feb 2007 15:10:21 +0000
  • Delivery-date: Wed, 21 Feb 2007 07:09:47 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AcdO73yfygbdSnxbR/2AnMRpBcbdNgAy2MewAXo9PloACVlAIAAAS21y
  • Thread-topic: [Xen-devel] [PATCH][TOOLS] Reducing impact ofdomainsave/restore/dump on Dom0

On 21/2/07 15:06, "Graham, Simon" <Simon.Graham@xxxxxxxxxxx> 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

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