This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] Benchmark results

To: <bbmailing@xxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Benchmark results
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Sun, 03 Aug 2008 18:07:39 +0100
Delivery-date: Sun, 03 Aug 2008 10:08:02 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <1409402707@xxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: Acj1i27nrWMhqmF+Ed21FgAWy6hiGQ==
Thread-topic: [Xen-devel] Benchmark results
User-agent: Microsoft-Entourage/
If the virtual disc is a loopback-mounted file then the domU is probably
benefitting from dom0's buffer cache (i.e., domU is happening to exploit
dom0's memory to cache its own data).

 -- Keir

On 3/8/08 17:51, "bbmailing@xxxxxx" <bbmailing@xxxxxx> wrote:

> Hey everyone,
> I hope you guys can help me explaining a pretty strange result that came up
> when benchmarking a native Red Hat installation against a Xen DomU (installed
> in a file container). I used lmbench3 on a dualcore AMD-machine. To make the
> results comparable, I "unplugged" all CPU cores but one in the native
> installation (setting the "online"-entry to 0). The DomU had only one vCPU
> assigned. The installed packages on both machines were identical as well.
> After doing the initial configuration of lmbench3 I ran a script doing 10
> times a "make rerun".
> All results seem to be OK somehow. But I cannot explain why Xen is faster than
> the native installation when creating and deleting files? Its 12ms (DomU)
> against 24ms (native) for creating a 0K file and 50ms (DomU) against 60ms
> (native) for creating a 10K file. Please find all the results attached.
> Is there any way this is possible? Maybe the communication methods used by the
> shared device drivers make the virtual machine think the operation has been
> finished successfully faster than the native way? Is there is anyone out there
> who can help me understanding this result?
> Furthermore: Is there a special recommendation for benchmarking Xen against
> native installations? I liked lmbench so far since it puts the focus on basic
> operations... what are your favourites? Is lmbench from a design perspective
> the wrong tool to use?
> I have to find some reliable results so I am really thankful for every single
> hint here... please feel free to email me directly as well!
> Thank you so much in advance!
> Best regards,
> Bjoern 
> _______________________________________________________________________
> Jetzt neu! Schützen Sie Ihren PC mit McAfee und WEB.DE. 30 Tage
> kostenlos testen. http://www.pc-sicherheit.web.de/startseite/?mc=022220
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel

Xen-devel mailing list

<Prev in Thread] Current Thread [Next in Thread>