From: Julien Grall <julien.grall@linaro.org>
To: Vijay Kilari <vijay.kilari@gmail.com>,
Ian Campbell <Ian.Campbell@citrix.com>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
Subject: Re: xen/arm: VCPU scheduling
Date: Mon, 22 Dec 2014 11:36:58 +0100 [thread overview]
Message-ID: <5497F44A.7030201@linaro.org> (raw)
In-Reply-To: <CALicx6tEQ+MXu51UN55KtVwDRPECNgqnvMaAM_MivubB7AsO+g@mail.gmail.com>
On 20/12/2014 20:48, Vijay Kilari wrote:
> Hi,
Hi Vijay,
>
> I want to know what is the criteria followed in Xen for scheduling VCPUs.
> Assume below scenario:
>
> - Run 2 VPCUs on 1 Physical CPU
> - VCPUs does not trap on WFE or WFE ( either by WFI/WFE trap is
> disabled in HCR OR no WFE/WFI in EL1 is executed).
>
> In such scenario, does Xen assumes that VCPU0 is always running because it has
> NOT trapped on WFI and WFE (not yielded voluntary) and does not
> schedule VCPU1? or is it time shared?
The scheduler allocates time slice to each VCPU. Once the slice is
ending, another VCPU may be scheduled.
Xen is also trapping WFE/WFI to allow better performance. Why would you
want to disable WFE/WFI traps?
Regards,
--
Julien Grall
prev parent reply other threads:[~2014-12-22 10:36 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-20 19:48 xen/arm: VCPU scheduling Vijay Kilari
2014-12-22 10:36 ` Julien Grall [this message]
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