Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

2016-09-10 0:38 GMT+08:00 Paolo Bonzini : > > > On 09/09/2016 00:13, David Matlack wrote: >> Hi Paolo, >> >> On Tue, Sep 6, 2016 at 3:29 PM, Paolo Bonzini wrote: >>> Bad things happen if a guest using the TSC deadline timer is migrated. >>> The guest

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

2016-09-10 0:38 GMT+08:00 Paolo Bonzini : > > > On 09/09/2016 00:13, David Matlack wrote: >> Hi Paolo, >> >> On Tue, Sep 6, 2016 at 3:29 PM, Paolo Bonzini wrote: >>> Bad things happen if a guest using the TSC deadline timer is migrated. >>> The guest doesn't re-calibrate the TSC after migration,

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

2016-09-16 17:06+0200, Paolo Bonzini: > On 16/09/2016 16:59, Radim Krčmář wrote: >> KVM_MSR_DEADLINE would be interface in kvmclock nanosecond values and >> MSR_IA32_TSCDEADLINE in TSC values. KVM_MSR_DEADLINE would follow >> similar rules as MSR_IA32_TSCDEADLINE -- the interrupt fires when >>

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

2016-09-16 17:06+0200, Paolo Bonzini: > On 16/09/2016 16:59, Radim Krčmář wrote: >> KVM_MSR_DEADLINE would be interface in kvmclock nanosecond values and >> MSR_IA32_TSCDEADLINE in TSC values. KVM_MSR_DEADLINE would follow >> similar rules as MSR_IA32_TSCDEADLINE -- the interrupt fires when >>

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

On 16/09/2016 16:59, Radim Krčmář wrote: > KVM_MSR_DEADLINE would be interface in kvmclock nanosecond values and > MSR_IA32_TSCDEADLINE in TSC values. KVM_MSR_DEADLINE would follow > similar rules as MSR_IA32_TSCDEADLINE -- the interrupt fires when > kvmclock reaches the value, you read what

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

On 16/09/2016 16:59, Radim Krčmář wrote: > KVM_MSR_DEADLINE would be interface in kvmclock nanosecond values and > MSR_IA32_TSCDEADLINE in TSC values. KVM_MSR_DEADLINE would follow > similar rules as MSR_IA32_TSCDEADLINE -- the interrupt fires when > kvmclock reaches the value, you read what

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

2016-09-15 23:02+0200, Paolo Bonzini: > On 15/09/2016 21:59, Radim Krčmář wrote: >> 2016-09-15 18:00+0200, Paolo Bonzini: When we are already going the paravirtual route, we could add an interface that accepts the deadline in kvmclock nanoseconds. It would be much more maintanable

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

2016-09-15 23:02+0200, Paolo Bonzini: > On 15/09/2016 21:59, Radim Krčmář wrote: >> 2016-09-15 18:00+0200, Paolo Bonzini: When we are already going the paravirtual route, we could add an interface that accepts the deadline in kvmclock nanoseconds. It would be much more maintanable

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

On 15/09/2016 21:59, Radim Krčmář wrote: > 2016-09-15 18:00+0200, Paolo Bonzini: >> So virtual_tsc_khz does change on migration, at least if your host >> doesn't have TSC scaling (which is pretty much all Intel hosts in >> existence). > > Ugh, I'd consider exposing constant TSC to the guest

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

On 15/09/2016 21:59, Radim Krčmář wrote: > 2016-09-15 18:00+0200, Paolo Bonzini: >> So virtual_tsc_khz does change on migration, at least if your host >> doesn't have TSC scaling (which is pretty much all Intel hosts in >> existence). > > Ugh, I'd consider exposing constant TSC to the guest

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

2016-09-15 18:00+0200, Paolo Bonzini: > On 15/09/2016 17:09, Radim Krčmář wrote: >> 2016-09-07 00:29+0200, Paolo Bonzini: >>> Bad things happen if a guest using the TSC deadline timer is migrated. >>> The guest doesn't re-calibrate the TSC after migration, and the >>> TSC frequency can and will

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

2016-09-15 18:00+0200, Paolo Bonzini: > On 15/09/2016 17:09, Radim Krčmář wrote: >> 2016-09-07 00:29+0200, Paolo Bonzini: >>> Bad things happen if a guest using the TSC deadline timer is migrated. >>> The guest doesn't re-calibrate the TSC after migration, and the >>> TSC frequency can and will

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

On 15/09/2016 17:09, Radim Krčmář wrote: > 2016-09-07 00:29+0200, Paolo Bonzini: >> Bad things happen if a guest using the TSC deadline timer is migrated. >> The guest doesn't re-calibrate the TSC after migration, and the >> TSC frequency can and will change unless your processor supports TSC >>

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

On 15/09/2016 17:09, Radim Krčmář wrote: > 2016-09-07 00:29+0200, Paolo Bonzini: >> Bad things happen if a guest using the TSC deadline timer is migrated. >> The guest doesn't re-calibrate the TSC after migration, and the >> TSC frequency can and will change unless your processor supports TSC >>

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

2016-09-07 00:29+0200, Paolo Bonzini: > Bad things happen if a guest using the TSC deadline timer is migrated. > The guest doesn't re-calibrate the TSC after migration, and the > TSC frequency can and will change unless your processor supports TSC > scaling (on Intel this is only Skylake) or your

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

2016-09-07 00:29+0200, Paolo Bonzini: > Bad things happen if a guest using the TSC deadline timer is migrated. > The guest doesn't re-calibrate the TSC after migration, and the > TSC frequency can and will change unless your processor supports TSC > scaling (on Intel this is only Skylake) or your

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

On Fri, Sep 9, 2016 at 9:38 AM, Paolo Bonzini wrote: > > On 09/09/2016 00:13, David Matlack wrote: >> Hi Paolo, >> >> On Tue, Sep 6, 2016 at 3:29 PM, Paolo Bonzini wrote: >>> Bad things happen if a guest using the TSC deadline timer is migrated. >>> The

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

On Fri, Sep 9, 2016 at 9:38 AM, Paolo Bonzini wrote: > > On 09/09/2016 00:13, David Matlack wrote: >> Hi Paolo, >> >> On Tue, Sep 6, 2016 at 3:29 PM, Paolo Bonzini wrote: >>> Bad things happen if a guest using the TSC deadline timer is migrated. >>> The guest doesn't re-calibrate the TSC after

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

On 09/09/2016 00:13, David Matlack wrote: > Hi Paolo, > > On Tue, Sep 6, 2016 at 3:29 PM, Paolo Bonzini wrote: >> Bad things happen if a guest using the TSC deadline timer is migrated. >> The guest doesn't re-calibrate the TSC after migration, and the >> TSC frequency can

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

On 09/09/2016 00:13, David Matlack wrote: > Hi Paolo, > > On Tue, Sep 6, 2016 at 3:29 PM, Paolo Bonzini wrote: >> Bad things happen if a guest using the TSC deadline timer is migrated. >> The guest doesn't re-calibrate the TSC after migration, and the >> TSC frequency can and will change

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

Hi Paolo, On Tue, Sep 6, 2016 at 3:29 PM, Paolo Bonzini wrote: > Bad things happen if a guest using the TSC deadline timer is migrated. > The guest doesn't re-calibrate the TSC after migration, and the > TSC frequency can and will change unless your processor supports TSC >

Re: [PATCH 2/2] x86, kvm: use kvmclock to compute TSC deadline value

Hi Paolo, On Tue, Sep 6, 2016 at 3:29 PM, Paolo Bonzini wrote: > Bad things happen if a guest using the TSC deadline timer is migrated. > The guest doesn't re-calibrate the TSC after migration, and the > TSC frequency can and will change unless your processor supports TSC > scaling (on Intel