host cpu frequency scaling and guest bogomips
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
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
- - V. Condino
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.1 (GNU/Linux)
iD8DBQFC01SbW5g8mX2/4TYRAjs0AKCKRXwTy6g/UK5w5ioA8WxpgcB/3QCfRZyj H9HTVRNl0FzeqUiYRxwrTAg=
=VsPI
-----END PGP SIGNATURE-----
-------------------------------------------------------
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 [email protected]
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
Quoted 12 lines · Victor Condino
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/cpuinforeported ~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.
Quoted 2 lines
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...
Quoted 1 line
- V. Condino
Signature · 20 lines
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! Messenger: chiamate gratuite in tutto il mondo http://it.beta.messenger.yahoo.com ------------------------------------------------------- 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 [email protected] https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
Quoted 7 lines · Blaisorblade
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...
hmm... so the moral is, CONFIG_UML_REAL_TIME_CLOCK is a "good thing"(tm) if your host is going to vary it's core freq?
- - V.C.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.1 (GNU/Linux)
iD8DBQFC0+73W5g8mX2/4TYRAvv3AJ9uA3HzbsM27evJHwUofX+1WOViMACfRL3J AqZgxrkfanj50IaQxjdcyec=
=K/Cr
-----END PGP SIGNATURE-----
-------------------------------------------------------
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 [email protected]
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
Quoted 15 lines · Blaisorblade
Quoted 12 lines · Victor Condino
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/cpuinforeported ~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.Quoted 2 lines
Not that this actually affects anything I do or would affect most people... just thought you guys might want to know =D
Quoted 7 lines
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()...
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
-------------------------------------------------------
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 [email protected]
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
Quoted 23 lines · Geert Uytterhoeven
Quoted 21 lines · Blaisorblade
Quoted 12 lines · Victor Condino
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/cpuinforeported ~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.Quoted 2 lines
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.
Quoted 4 lines
Quoted 2 lines
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()ormdelay()...
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.
Signature · 23 lines
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 [email protected] https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel