lkml.org 
[lkml]   [2011]   [Jun]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 3/7] KVM-HV: KVM Steal time implementation
    On Sun, Jun 19, 2011 at 03:35:58PM +0300, Avi Kivity wrote:
    > On 06/15/2011 12:09 PM, Gleb Natapov wrote:
    > >>
    > >> Actually, I'd expect most read/writes to benefit from caching, no?
    > >> So why don't we just rename kvm_write_guest_cached() to
    > >> kvm_write_guest(), and the few places - if any - that need to force
    > >> transversing of the gfn mappings, get renamed to
    > >> kvm_write_guest_uncached ?
    > >>
    > >Good idea. I do not see any places where kvm_write_guest_uncached is
    > >needed from a brief look. Avi?
    > >
    >
    > kvm_write_guest_cached() needs something to supply the cache, and
    > needs recurring writes to the same location. Neither of these are
    > common (for example, instruction emulation doesn't have either).
    >
    Correct. Missed that. So what about changing steal time to use
    kvm_write_guest_cached()?

    > >>
    > >> If done like you said, time spent on the hypervisor is accounted as
    > >> steal time. I don't think it is.
    > >I thought that this is the point of a steal time. Running other
    > >tasks/guests is a hypervisor overhead too after all :) Also what about
    > >time spend serving host interrupts between put/get? It will not be
    > >accounted as steal time, correct?
    >
    > With accurate interrupt time accounting, it should be. Otherwise
    > general hypervisor overhead is not steal time.
    >
    > (i.e. if the host is not overcommitted, steal time should be close to zero).
    >

    --
    Gleb.


    \
     
     \ /
      Last update: 2011-06-19 15:03    [W:0.021 / U:29.976 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site