On 05/01/2013 13:49, Lon Willett wrote: > On 2012-12-25 00:05, Gordon Messmer wrote: >> Following the announcement of comBIOS 1.41c for the Soekris 6501, I did >> some work on addressing the remaining quirks present when using CentOS 6 >> x86_64. Hopefully this information is useful to other Linux users. >> These are the notes that I shared with my coworkers: >> >> We updated the kernel parameters to include: >> pcie_aspm=off processor.max_cstate=1 clocksource=tsc > I'm running Debian Wheezy, with a 32 bit 3.6.6 kernel including the HPET > quirks patch. I looked into these settings, and found the following: > > pcie_aspm=off -- not needed; ASPM seems to be disabled for this chipset > already. > > processor.max_cstate=1 -- not used; one can get a similar effect with > "intel_idle.max_cstate=1". > > clocksource=tsc -- not needed. If "intel_idle.max_cstate" is set to 1, > then TSC will be automatically selected as the clock source. Otherwise, > HPET will be used (since the kernel was compiled with the HPET quirks > patch). > > So my question, to anyone who knows, is whether it is better to use HPET > as the clocksource, or to set "intel_idle.max_cstate=1" and use TSC? Or > is there no noticeable difference? >
As long as the TSC is stable, which it should be on such a modern CPU, then it is the better timer to use. This is because it can be read very quickly using a single instruction, whereas reading the HPET requires a slow IO operation instead. HTH, Chris -- Chris Boot [email protected] _______________________________________________ Soekris-tech mailing list [email protected] http://lists.soekris.com/mailman/listinfo/soekris-tech
