On 2010-10-09 00:06, Marcelo Tosatti wrote: > On Thu, Oct 07, 2010 at 04:47:11PM -1000, Zachary Amsden wrote: >> On 10/07/2010 02:12 PM, Arjan Koers wrote: >>> On 2010-10-03 01:42, Zachary Amsden wrote: >>> ... >>>> Umm... do you guys have this commit? This is supposed to address the >>>> issue where the guest keeps resetting the TSC. A guest which does that >>>> will break kvmclock. It only happens on SMP, and it's much worse on AMD >>>> CPUs... >>>> >>>> sound like your scenario. >>>> >>>> commit bd59fc8ff95126f27b7a0df1b6cc602aa428812d >>>> Author: Zachary Amsden<zamsden@xxxxxxxxxx> >>>> Date: Thu Aug 19 22:07:26 2010 -1000 >>> >>> This commit fixes the problem: >>> >>> commit aad07c4f92bae2edaa42bcef84c2afdd0d082458 >>> Author: Zachary Amsden<zamsden@xxxxxxxxxx> >>> Date: Thu Aug 19 22:07:19 2010 -1000 >>> >>> KVM: x86: Move TSC reset out of vmcb_init >>> >>> The VMCB is reset whenever we receive a startup IPI, so Linux is setting >>> TSC back to zero happens very late in the boot process and destabilizing >>> the TSC. Instead, just set TSC to zero once at VCPU creation time. >>> >>> Why the separate patch? So git-bisect is your friend. >> >> Okay, apparently I need to go poke around 2.6.35 and see what >> patches made it there and what patches didn't. > > Backports attached. Michael, Arjan, please give them a try. > Thanks for the patches. Successfully tested with 2.6.34.7, 2.6.35.7 and 2.6.36-rc7 host (with a 2.6.35.7 guest). It failed with a 2.6.32.24 host. The patch applied, but pvclock_clocksource_read on the guest is still producing wrong results for CPU 1 while it's booting. I'll re-check tomorrow. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
