Messages in this thread | | | Subject | Re: [PATCH] xen: add steal_clock support on x86 | From | Juergen Gross <> | Date | Wed, 18 May 2016 17:42:02 +0200 |
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On 18/05/16 17:25, Boris Ostrovsky wrote: > On 05/18/2016 10:53 AM, Juergen Gross wrote: >> On 18/05/16 16:46, Boris Ostrovsky wrote: >>> On 05/18/2016 08:15 AM, Juergen Gross wrote: >>>> } >>>> >>>> +void __init xen_time_setup_guest(void) >>>> +{ >>>> + pv_time_ops.steal_clock = xen_steal_clock; >>>> + >>>> + static_key_slow_inc(¶virt_steal_enabled); >>>> + /* >>>> + * We can't set paravirt_steal_rq_enabled as this would require the >>>> + * capability to read another cpu's runstate info. >>>> + */ >>>> +} >>> Won't we be accounting for stolen cycles twice now --- once from >>> steal_account_process_tick()->steal_clock() and second time from >>> do_stolen_accounting()? >> Uuh, yes. >> >> I guess I should rip do_stolen_accounting() out, too? > > I don't think PARAVIRT_TIME_ACCOUNTING is always selected for Xen. If
This is easy to accomplish. :-)
> that's indeed the case then we should ifndef do_stolen_accounting(). Or > maybe check for paravirt_steal_enabled.
Is this really a sensible thing to do? There is a mechanism used by KVM to do the stolen accounting. I think we should use it instead of having a second implementation doing the same thing in case the generic one isn't enabled.
Juergen
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