From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Lieven <pl@dlhnet.de>
Cc: Vadim Rozenfeld <vrozenfe@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
kvm@vger.kernel.org, gleb@redhat.com, pl@dlh.net
Subject: Re: [RFC PATCH v2 1/2] add support for Hyper-V reference time counter
Date: Thu, 23 May 2013 15:40:23 +0200 [thread overview]
Message-ID: <519E1C47.3070700@redhat.com> (raw)
In-Reply-To: <519E1A09.5080601@dlhnet.de>
Il 23/05/2013 15:30, Peter Lieven ha scritto:
>>>> So I would prefer to remove kvm->arch.hv_ref_count altogether.
>>>
>>> But only if the migration support is guaranteed.
>>
>> Migration support wouldn't work yet anyway, you need to recompute the
>> scale and sequence. But that could be done by KVM_SET_CLOCK.
>
> hv_ref_counter does work out of the box. what I was trying to say is
> even it is slower than iTSC, it is significantly faster than hpet
> or pmtimer and I can confirm it works flawlessly with migration.
I can't see how without a userspace patch to migrate hv_ref_count.
>>> And what if we have a host which lacks invariant TSC support?
>>
>> Then the sequence must be set to 0 or 0xFFFFFFFF, I still haven't
>> understood. :)
>
> yes, but windows does then fall back to pmtimer or hpet which is much
> slower then reference counter.
IIUC, with 0 it doesn't.
Paolo
next prev parent reply other threads:[~2013-05-23 13:40 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-19 7:06 [RFC PATCH v2 0/2] Hyper-V timers Vadim Rozenfeld
2013-05-19 7:06 ` [RFC PATCH v2 1/2] add support for Hyper-V reference time counter Vadim Rozenfeld
2013-05-19 13:47 ` Gleb Natapov
2013-05-19 14:37 ` Paolo Bonzini
2013-05-22 0:46 ` Marcelo Tosatti
2013-05-22 3:28 ` Gleb Natapov
2013-05-22 3:32 ` Marcelo Tosatti
2013-05-22 3:38 ` Gleb Natapov
2013-05-22 14:31 ` Marcelo Tosatti
2013-05-22 7:32 ` Vadim Rozenfeld
2013-05-22 21:55 ` Paolo Bonzini
2013-05-23 6:17 ` Peter Lieven
2013-05-23 9:54 ` Paolo Bonzini
2013-05-23 10:45 ` Peter Lieven
2013-05-23 12:25 ` Vadim Rozenfeld
2013-05-23 13:18 ` Paolo Bonzini
2013-05-23 13:20 ` Peter Lieven
2013-05-23 13:23 ` Paolo Bonzini
2013-05-23 13:30 ` Peter Lieven
2013-05-23 13:40 ` Paolo Bonzini [this message]
2013-05-19 7:06 ` [RFC PATCH v2 2/2] add support for Hyper-V invariant TSC Vadim Rozenfeld
2013-05-22 0:50 ` Marcelo Tosatti
2013-05-22 7:22 ` Vadim Rozenfeld
2013-05-22 21:23 ` Marcelo Tosatti
2013-05-23 6:18 ` Peter Lieven
2013-05-23 9:13 ` Gleb Natapov
2013-05-23 13:35 ` Marcelo Tosatti
2013-05-23 15:14 ` Gleb Natapov
2013-05-24 9:57 ` Vadim Rozenfeld
2013-05-23 12:33 ` Vadim Rozenfeld
2013-05-23 12:44 ` Peter Lieven
2013-05-23 12:45 ` Gleb Natapov
2013-05-23 12:54 ` Vadim Rozenfeld
2013-05-23 9:12 ` Gleb Natapov
2013-05-23 13:53 ` Marcelo Tosatti
2013-05-23 15:31 ` Gleb Natapov
2013-05-24 10:11 ` Vadim Rozenfeld
2013-05-24 19:41 ` Marcelo Tosatti
2013-05-27 12:33 ` Vadim Rozenfeld
2013-05-23 12:21 ` Vadim Rozenfeld
2013-05-23 13:47 ` Marcelo Tosatti
2013-05-24 10:01 ` Vadim Rozenfeld
2013-05-23 16:44 ` Paolo Bonzini
2013-05-24 10:16 ` Vadim Rozenfeld
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