Re: [PATCH] xen-hvm: Allow disabling buffer_io_timer

[Jason Andryuk <jandryuk@xxxxxxxxx>]

On Tue, Dec 14, 2021 at 8:40 AM Durrant, Paul <xadimgnik@xxxxxxxxx> wrote:
>
> On 10/12/2021 11:34, Jason Andryuk wrote:
> > commit f37f29d31488 "xen: slightly simplify bufioreq handling" hard
> > coded setting req.count = 1 during initial field setup before the main
> > loop.  This missed a subtlety that an early exit from the loop when
> > there are no ioreqs to process, would have req.count == 0 for the return
> > value.  handle_buffered_io() would then remove state->buffered_io_timer.
> > Instead handle_buffered_iopage() is basically always returning true and
> > handle_buffered_io() always re-setting the timer.
> >
> > Restore the disabling of the timer by introducing a new handled_ioreq
> > boolean and use as the return value.  The named variable will more
> > clearly show the intent of the code.
> >
> > Signed-off-by: Jason Andryuk <jandryuk@xxxxxxxxx>
>
> Reviewed-by: Paul Durrant <paul@xxxxxxx>

Thanks, Paul.

What is the next step for getting this into QEMU?

To re-state more plainly, this patch fixes a bug to let QEMU go idle
for longer stretches of time.  Without it, buffer_io_timer continues
to re-arm and fire every 100ms even if there is nothing to do.

Regards,
Jason