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Re: [Xen-devel] [PATCH] xen/arm: Don't save/restore context for idle VCPU

On Wed, 2014-07-09 at 16:50 +0100, Ian Campbell wrote:
> On Mon, 2014-07-07 at 16:29 +0100, Julien Grall wrote:
> > When an idle VCPU is running, Xen will never exit the hypervisor mode.
> > Futhermore, some part of the VCPU/domain initialization is already skipped 
> > for
> > them to avoid memory consumption.
> > 
> > Actually each save/restore functions are checking themself if the vcpu is
> > an idle one or not. We can safely skipped the context switch in one place
> > and gain a bit of time when we {,un}schedule idle VCPU. This is because
> > the saving part will take care of disabling anything related to guest (such
> > as GICv).
> > 
> > Also replace every check of and idle VCPU in save/restore functions by an
> > ASSERT, to know if someone is calling them with an idle VCPU in argument.
> > 
> > Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>


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