On Fri, Feb 19, 2016 at 15:44:23 +0100, Radim Krčmář wrote: > [Cc'd Peter, the last guy that touched timers in libvirt, because he > might know what tick policies are supposed to be.] I found the following RFC that describes the design of timer access in libvirt: http://www.redhat.com/archives/libvir-list/2010-March/msg00304.html > > 2016-02-18 18:55+0100, Paolo Bonzini: > > On 18/02/2016 18:33, Paolo Bonzini wrote: > >> On 18/02/2016 17:56, Radim Krčmář wrote: > >>> 2016-02-18 17:13+0100, Paolo Bonzini: > >>>> On 17/02/2016 20:14, Radim Krčmář wrote: > >>>>> Discard policy uses ack_notifiers to prevent injection of PIT interrupts > >>>>> before EOI from the last one. > >>>>> > >>>>> This patch changes the policy to always try to deliver the interrupt, > >>>>> which makes a difference when its vector is in ISR. > >>>>> Old implementation would drop the interrupt, but proposed one injects to > >>>>> IRR, like real hardware would. > >>>> > >>>> This seems like what libvirt calls the "merge" policy: > >>> > >>> Oops, I never looked beyond QEMU after seeing that the naming in libvirt > >>> doesn't even match ... > >>> > >>> I think the policy that KVM implements (which I call discard) is "delay" > >>> in libvirt. (https://libvirt.org/formatdomain.html#elementsTime) > > (I looked at libvirt code, but couldn't find any use of merge or discard > policies, so please bear with me as I disagree wherever it's possible.) Indeed, it looks like it never was implemented. Unfortunately i'm not able to assist more in this case. Peter
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