From: Blaisorblade <blaisorblade@yahoo.it>
To: user-mode-linux-devel@lists.sourceforge.net
Cc: Victor Condino <un1tz3r0@gmail.com>
Subject: Re: [uml-devel] host cpu frequency scaling and guest bogomips
Date: Tue, 12 Jul 2005 17:56:39 +0200 [thread overview]
Message-ID: <200507121756.40169.blaisorblade@yahoo.it> (raw)
In-Reply-To: <42D3549D.50308@gmail.com>
On Tuesday 12 July 2005 07:26, Victor Condino wrote:
> just noticed something interesting while testing out my gentoo/uml
> root-fs generation script on my laptop. my l/t is an thinkpad T42p,
> which has a p3 centrino with speedstep. i use cpufreqd to throttle the
> cpu when not on ac between 600 and 1800MHz based on load. what i noticed
> is that when I fired up UML while the host's core frequency was at
> 600mhz, /proc/cpuinfo reported ~600 bogomips in the guest, but when i
> put some load on the host and cpufreq stepped up the core frequency, UML
> still reports ~600 bogomips. likewise, when I fired up UML while the
> host was under load and it's core at 1200MHz, UML reports higher
> bogomips, but then when the host drops back down to the lower core freq,
> UML still reports the same higher bogomips.
> Not that this actually affects anything I do or would affect most
> people... just thought you guys might want to know =D
Hmm, bogomips are calculated at startup and that won't change easily. However,
they become inaccurate in a much wider variety of situation, for instance
when there's some load on the host; so, using CONFIG_UML_REAL_TIME_CLOCK
(IIRC) uses the host clock for time calculation.
When you disable this option, I guess that a "sleep 10" when host is at 600,
if UML was started at 1800, might last 30 seconds more or less...
> - V. Condino
--
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
http://www.user-mode-linux.org/~blaisorblade
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next prev parent reply other threads:[~2005-07-12 15:49 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-07-12 5:26 [uml-devel] host cpu frequency scaling and guest bogomips Victor Condino
2005-07-12 15:56 ` Blaisorblade [this message]
2005-07-12 16:25 ` Victor Condino
2005-07-12 16:35 ` Geert Uytterhoeven
2005-07-12 17:14 ` Blaisorblade
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