On Wed, 2009-09-09 at 16:16 +0300, Alexander Motin wrote: > Robert Noland wrote: > > On Wed, 2009-09-09 at 17:47 +0930, Daniel O'Connor wrote: > >> On Wed, 9 Sep 2009, Alexander Motin wrote: > >>> Daniel O'Connor wrote: > >>>> On Wed, 9 Sep 2009, Alexander Motin wrote: > >>>>> Daniel O'Connor wrote: > >>>>>> I recently discovered a system where the floppy drive cable was > >>>>>> intermittently fouling the CPU fan - I believe this caused the > >>>>>> CPU to overheat and then get throttled by the BIOS. > >>>>>> > >>>>>> Does anyone know if it is possible to determine if this is the > >>>>>> case? ie is there a way to be informed if throttling has > >>>>>> occurred? > >>>>> Theoretically it is possible. I know off-topic tool reporting > >>>>> this. Also you can just monitor CPU temperature, depending on CPU > >>>>> type. > >>>> Monitoring CPU temperature is a bit difficult, there are a lack of > >>>> tools (although I have some code it's not complete). > >>> There indeed problems with MB monitoring, as it is non-standard. But > >>> modern CPUs also include on-chip thermal sensors. For Core2Duo family > >>> coretemp module works fine and precisely. > >> Ahh coretemp, I had forgotten about that. > >> > >> I did a test on the bench (on a 7.2 system) here and realised that I > >> can't actually detect throttling. coretemp reported 72 & 78C but the > >> frequency was still 2933MHz. > >> > >> I am pretty sure it would be throttling but I think that works by > >> maintaining the frequency but stalling the CPU some percentage of the > >> time. I have p4tcc loaded (in GENERIC) but it doesn't show up, I only > >> get.. > > > > Is this a core2duo? IIRC, they generally don't go into TCC until around > > 100C. I did pull the c2d cpu docs at one point trying to look at > > cpufreq. If you are bored, you can grab the docs from intel and double > > check. > > AFAIR C2D supports three protection technologies. When CPU is hot, it > starts reducing frequency (multiplier) and voltage, alike to IEST. If it > is insufficient, it starts to skip core cycles, alike to TCC. If it is > still insufficient and temperature rises above about 100C, emergency > shutdown happens.
Your recollection is probably more accurate than mine. My brain is full, so every new doc that I read pushes something else out. robert. -- Robert Noland <rnol...@freebsd.org> FreeBSD _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
