Re: [Xen-devel] [PATCH v6.1 08/20] xen/sched: make vcpu_wake() and vcpu_sleep() core scheduling aware

[Julien Grall <julien.grall@xxxxxxx>]

Hi,

On 10/2/19 3:43 PM, Juergen Gross wrote:
> vcpu_wake() and vcpu_sleep() need to be made core scheduling aware:
> they might need to switch a single vcpu of an already scheduled unit
> between running and not running.
>
> Especially when vcpu_sleep() for a vcpu is being called by a vcpu of
> the same scheduling unit special care must be taken in order to avoid
> a deadlock: the vcpu to be put asleep must be forced through a
> context switch without doing so for the calling vcpu. For this
> purpose add a vcpu flag handled in sched_slave() and in
> sched_wait_rendezvous_in() allowing a vcpu of the currently running
> unit to switch state at a higher priority than a normal schedule
> event.
>
> Use the same mechanism when waking up a vcpu of a currently active
> unit.
>
> While at it make vcpu_sleep_nosync_locked() static as it is used in
> schedule.c only.
>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> Reviewed-by: Dario Faggioli <dfaggioli@xxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxx>

Dario, can you confirm you are happy with the slight changes to cater Arm?

Cheers,

--
Julien Grall

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