Marcelo Tosatti wrote: > On Tue, Oct 28, 2008 at 12:36:14PM -0600, David S. Ahern wrote: >>> That is, the fact that KVM does not handle unsynced TSC's on the host is >>> not an argument against this patch which clearly fixes a bug. >>> >>> Take commit 019960ae9933161c2809fa4ee608ba30d9639fd2 for example. >>> >> Has anything changed "recently" with the TSC code? Recently here being >> the past 2 months since you first crafted the patch. I ask because in >> the past few runs based on kvm.git trees (e.g., as recently as a pull on >> 10/26), this tsc offset patch no longer fixes the problem. > > Hi David, > > Can you share showtime output? Works for me. >
Hi Marcelo: I pulled kvm.git this morning and ran three cases: 1. kvm.git with no patches, 2. kvm.git with your TSC offset patch from September 10th, 3. kvm.git with TSC offset set to 0. In all cases the host is a DL380G5, Fedora 9 OS, kvm-77 userspace. Guest is running RHEL3U8. 3 samples for each case: 1. kvm.git, no patches: cpu 0: 1225374376.351910 * cpu 1: 1225374376.598833 cpu 2: 1225374378.154530 cpu 3: 1225374377.874563 * sleeping 1 with affinity set to 0x8 cpu 0: 1225374377.361762 * cpu 1: 1225374377.608669 cpu 2: 1225374379.164366 cpu 3: 1225374378.884393 * sleeping 1 with affinity set to 0x8 cpu 0: 1225374378.371607 * cpu 1: 1225374378.618517 cpu 2: 1225374380.174213 cpu 3: 1225374379.894246 * 2. kvm.git, Marcelo patch cpu 0: 1225374671.069711 cpu 1: 1225374671.069711 cpu 2: 1225374671.069804 cpu 3: 1225374671.069761 * sleeping 1 with affinity set to 0x8 cpu 0: 1225374672.079221 cpu 1: 1225374672.079220 * cpu 2: 1225374672.079309 cpu 3: 1225374672.079267 * sleeping 1 with affinity set to 0x8 cpu 0: 1225374673.088703 cpu 1: 1225374673.088701 * cpu 2: 1225374673.088802 cpu 3: 1225374673.088763 * 3. tsc offset 0 cpu 0: 1225374910.953226 cpu 1: 1225374910.953307 cpu 2: 1225374910.953355 cpu 3: 1225374910.953446 sleeping 1 with affinity set to 0x8 cpu 0: 1225374911.962735 cpu 1: 1225374911.962808 cpu 2: 1225374911.962857 cpu 3: 1225374911.962949 sleeping 1 with affinity set to 0x8 cpu 0: 1225374912.972211 cpu 1: 1225374912.972284 cpu 2: 1225374912.972333 cpu 3: 1225374912.972425 I'll repeat the test later on a PowerEdge 2950 with a similar setup, but it has the same processor as the DL380G5. david >> The following one does fix the problem with kvm.git pulled on 10/26/08: >> >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >> index 64e2439..d5da717 100644 >> --- a/arch/x86/kvm/vmx.c >> +++ b/arch/x86/kvm/vmx.c >> @@ -860,7 +860,7 @@ static void guest_write_tsc(u64 guest_tsc) >> u64 host_tsc; >> >> rdtscll(host_tsc); >> - vmcs_write64(TSC_OFFSET, guest_tsc - host_tsc); >> + vmcs_write64(TSC_OFFSET, 0); >> } >> >> /* >> >> This is the vmx counterpart (or at least to my understanding) to a >> suggestion Ben had for the svm code. >> >> david -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
