Re: [Qemu-block] [PATCH RFC v3 2/8] block: Add aio_context field in ThrottleGroupMember

[Manos Pitsidianakis]

On Wed, Jun 28, 2017 at 01:27:36PM +0200, Kevin Wolf wrote:
> Am 23.06.2017 um 14:46 hat Manos Pitsidianakis geschrieben:
> > timer_cb() needs to know about the current Aio context of the throttle
> > request that is woken up. In order to make ThrottleGroupMember backend
> > agnostic, this information is stored in an aio_context field instead of
> > accessing it from BlockBackend.
> >
> > Signed-off-by: Manos Pitsidianakis <address@hidden>
>
> You're copying the AioContext when the BlockBackend is registered for
> the throttle group, but what keeps both sides in sync when the context
> is changed later on? Don't we need to update the ThrottleGroupMember in
> blk_set_aio_context?

blk_set_aio_context calls throttle_timers_attach_aio_context which 
updates this. Though as Alberto said util/throttle.c should not know 
about ThrottleGroupMember. This is not needed in the later patches 
because the ThrottleGroupMember's aio_context gets updated as a node in 
the driver's bdrv_attach_aio_context

We can add a new function in block/throttle.c that updates a member's 
aio context but I'm not sure if it's really needed if members are only 
used in throttle nodes.

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