On Tuesday 12 July 2005 18:35, Geert Uytterhoeven wrote: > On Tue, 12 Jul 2005, Blaisorblade wrote: > > 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... > I don't think user space sleep uses the kernel's udelay() or mdelay()... Sorry, right... they're the only one to use bogomips (just learned), still UML_REAL_TIME_CLOCK makes "sleep(1)" in user-space precise. That option drops the assumption that SIGALRM (or VTALRM) is exact, and rather, at ALRM delivery, uses gettimeofday() to discover how long passed from last interrupt. -- 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 ___________________________________ Yahoo! Mail: gratis 1GB per i messaggi e allegati da 10MB http://mail.yahoo.it ------------------------------------------------------- This SF.Net email is sponsored by the 'Do More With Dual!' webinar happening July 14 at 8am PDT/11am EDT. We invite you to explore the latest in dual core and dual graphics technology at this free one hour event hosted by HP, AMD, and NVIDIA. To register visit http://www.hp.com/go/dualwebinar _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
