Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support

2017-02-17 Thread Thomas Gleixner
On Fri, 17 Feb 2017, Andy Lutomirski wrote: > On Fri, Feb 17, 2017 at 2:14 AM, Vitaly Kuznetsov wrote: > > Not only. As far as I understand (and I *think* K. Y. pointed this out) > > when VM is migrating to another host TSC page clocksource is disabled for > > extended period

Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support

2017-02-17 Thread Andy Lutomirski
On Fri, Feb 17, 2017 at 2:14 AM, Vitaly Kuznetsov wrote: > Thomas Gleixner writes: > >> On Wed, 15 Feb 2017, Vitaly Kuznetsov wrote: >>> Actually, we already have an implementation of TSC page update in KVM >>> (see arch/x86/kvm/hyperv.c,

Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support

2017-02-17 Thread Thomas Gleixner
On Fri, 17 Feb 2017, Vitaly Kuznetsov wrote: > Thomas Gleixner writes: > > On Wed, 15 Feb 2017, Vitaly Kuznetsov wrote: > >> Actually, we already have an implementation of TSC page update in KVM > >> (see arch/x86/kvm/hyperv.c, kvm_hv_setup_tsc_page()) and the update does > >>

Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support

2017-02-17 Thread Vitaly Kuznetsov
Thomas Gleixner writes: > On Wed, 15 Feb 2017, Vitaly Kuznetsov wrote: >> Actually, we already have an implementation of TSC page update in KVM >> (see arch/x86/kvm/hyperv.c, kvm_hv_setup_tsc_page()) and the update does >> the following: >> >> 0) stash seq into seq_prev >>

Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support

2017-02-16 Thread Thomas Gleixner
On Wed, 15 Feb 2017, Vitaly Kuznetsov wrote: > Actually, we already have an implementation of TSC page update in KVM > (see arch/x86/kvm/hyperv.c, kvm_hv_setup_tsc_page()) and the update does > the following: > > 0) stash seq into seq_prev > 1) seq = 0 making all reads from the page invalid > 2)

Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support

2017-02-15 Thread Vitaly Kuznetsov
Andy Lutomirski writes: > On Tue, Feb 14, 2017 at 7:50 AM, Vitaly Kuznetsov wrote: >> Thomas Gleixner writes: >> >>> On Tue, 14 Feb 2017, Vitaly Kuznetsov wrote: >>> Hi, while we're still waiting for a definitive ACK

Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support

2017-02-14 Thread Andy Lutomirski
On Tue, Feb 14, 2017 at 7:50 AM, Vitaly Kuznetsov wrote: > Thomas Gleixner writes: > >> On Tue, 14 Feb 2017, Vitaly Kuznetsov wrote: >> >>> Hi, >>> >>> while we're still waiting for a definitive ACK from Microsoft that the >>> algorithm is good for SMP

Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support

2017-02-14 Thread Vitaly Kuznetsov
Thomas Gleixner writes: > On Tue, 14 Feb 2017, Vitaly Kuznetsov wrote: > >> Hi, >> >> while we're still waiting for a definitive ACK from Microsoft that the >> algorithm is good for SMP case (as we can't prevent the code in vdso from >> migrating between CPUs) I'd like to

Re: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support

2017-02-14 Thread Thomas Gleixner
On Tue, 14 Feb 2017, Vitaly Kuznetsov wrote: > Hi, > > while we're still waiting for a definitive ACK from Microsoft that the > algorithm is good for SMP case (as we can't prevent the code in vdso from > migrating between CPUs) I'd like to send v2 with some modifications to keep > the discussion

RE: [PATCH v2 0/3] x86/vdso: Add Hyper-V TSC page clocksource support

2017-02-14 Thread KY Srinivasan
> -Original Message- > From: Vitaly Kuznetsov [mailto:vkuzn...@redhat.com] > Sent: Tuesday, February 14, 2017 4:44 AM > To: x...@kernel.org; Andy Lutomirski > Cc: Thomas Gleixner ; Ingo Molnar ; > H. Peter Anvin