Re: [Xen-devel] [PATCHv3 4/6] evtchn: use a per-event channel lock for sending events

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.06.15 at 14:03, <david.vrabel@xxxxxxxxxx> wrote:
> When sending an event, use a new per-event channel lock to safely
> validate the event channel state.
> 
> This new lock must be held when changing event channel state.  Note
> that the event channel lock must also be held when changing state from
> ECS_FREE or it will race with a concurrent get_free_port() call.
> 
> To avoid having to take the remote event channel locks when sending to
> an interdomain event channel, the local and remote channel locks are
> both held when binding or closing an interdomain event channel.
> 
> This significantly  increases the  number of events  that can  be sent
> from multiple  VCPUs.  But struct  evtchn increases in  size, reducing
> the number that fit into a single page to 64 (instead of 128).
> 
> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

But iiuc this functionally depends on the earlier patches, and
hence can't go in without the issues there addressed.

Jan


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