From: Keir Fraser <keir.xen@gmail.com>
To: Juergen Gross <juergen.gross@ts.fujitsu.com>,
Jan Beulich <JBeulich@novell.com>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
Subject: Re: Performance difference between Xen versions
Date: Mon, 02 May 2011 07:41:06 +0100 [thread overview]
Message-ID: <C9E41092.170DB%keir.xen@gmail.com> (raw)
In-Reply-To: <4DBE41C9.1010409@ts.fujitsu.com>
On 02/05/2011 06:31, "Juergen Gross" <juergen.gross@ts.fujitsu.com> wrote:
>>> Is there any easy explanation for this? Both Xen versions are from SLES
>>> (SLES11 or SLES11 SP1).
>> I think cpufreq handling was off by default in 3.3, and is on by
>> default on 4.0. Try turning this off, or using the performance
>> governor.
> Jan, you got it! With cpufreq=none Xen 4.0 has more or less the same numbers
> as 3.3. Now I wonder why the default is so much slower. I looks as if the
> hypervisor would run at a lower speed. I can't believe it should behave like
> that!
It runs at lower frequency unless your test offers sufficient load over a
long enough time period. Short microbenchmarks are probably finished before
the frequency governor can react.
-- Keir
next prev parent reply other threads:[~2011-05-02 6:41 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-29 12:32 Performance difference between Xen versions Juergen Gross
2011-04-29 13:28 ` Keir Fraser
2011-04-29 13:35 ` Juergen Gross
2011-04-29 14:58 ` Keir Fraser
2011-04-29 16:10 ` Jan Beulich
2011-05-02 5:31 ` Juergen Gross
2011-05-02 6:41 ` Keir Fraser [this message]
2011-05-02 7:23 ` Jan Beulich
2011-05-02 8:00 ` Juergen Gross
2011-05-02 8:15 ` Jan Beulich
2011-05-02 8:23 ` Juergen Gross
2011-05-02 8:49 ` Keir Fraser
2011-05-03 3:06 ` Tian, Kevin
2011-05-06 13:49 ` Juergen Gross
2011-05-06 14:27 ` Jan Beulich
2011-05-11 6:08 ` Tian, Kevin
2011-05-11 6:23 ` Juergen Gross
2011-05-02 17:52 ` John Weekes
2011-05-02 18:12 ` Konrad Rzeszutek Wilk
2011-05-02 18:43 ` John Weekes
2011-05-02 19:16 ` John Weekes
2011-05-02 19:36 ` Konrad Rzeszutek Wilk
2011-05-02 19:54 ` John Weekes
2011-05-03 2:16 ` Tian, Kevin
2011-05-03 3:04 ` Tian, Kevin
2011-05-03 3:39 ` John Weekes
2011-05-03 7:23 ` Tian, Kevin
[not found] ` <4DBF13BB.3000309@nuclearfallout.net>
2011-05-03 7:23 ` Jan Beulich
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