Carsten Otte/Germany/[EMAIL PROTECTED] wrote on 10/11/2007 12:57:38 PM: > Dong, Eddie wrote: > > [EMAIL PROTECTED] wrote: > >> Jim Paris wrote: > >>> If I stop KVM in the monitor with "stop", wait a minute, and do > >>> "cont", a Linux guest gives me a "BUG: soft lockup detected on > >>> CPU#0". Is that expected behavior? > >> We have the same behavior on s390 when running in a virtual > >> environment. The issue is, that the guest physical cpu may be > >> scheduled away while a timer runs down. I don't think there's anything > >> kvm could do better regerding the soft lockup code. Soft lockup is > >> just broken for virtualized environments and needs to be fixed. For > >> the time being, just disable it in kconfig. > >> > > This is a well known issue, but we can fix by syncing TSC with PIT etc. > > But doing this we need to froze guest TSC when a VP is descheduled. > > > > We enable this in Xen but feel it is too complicated so never wanna > > to do same thing in KVM per previous discussion. There are some > > side effect of course due to this. > > > > In Xen some time you will see PV domain soft lockup, but never in > > hardware HVM :-) Hopefully Linux will have pv timer soon. > Yes, virtual timers will be the right fix for it. I believe Jan has a > patch for that. Am I mistaken Jan? [adding Jan to CC:]
Well, we have an instruction for that ;- (but that's not the whole story). The idea is simply to make sched_clock using a virtual timer, so softlockup does only account time the guest was scheduled. Currently we have softlockup disabled on s390 too, since there are some open issues with CFS and the virtual sched_clock. -- Jan ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
