I'm sorry for the delay in replying.
On Thu, 27 Mar 2025 14:43:54 +0100, Markus wrote:
> zoudongjie <zoudong...@huawei.com> writes:
> > On Thu, 27 Mar 2025 09:04:51 +0100, Markus wrote:
> >> zoudongjie <zoudong...@huawei.com> writes:
> >>
> >> > On Wed, Mar 26, 2025 at 10:53:20 +0100, Markus wrote:
> >> >> zoudongjie via <qemu-de...@nongnu.org> writes:
> >> >>
> >> >> > From: Zhu Yangyang <zhuyangyan...@huawei.com>
> >> >> >
> >> >> > Calling qmp_block_set_io_throttle() will be blocked for a long time
> >> >> > when a network disk is configured and the network failure is just
> >> >> > about
> >> >> > to occur.
> >>
> >> What other commands could similarly block?
> >
> > In theory, any command may be blocked if it calls bdrv_drained_begin().
> > I did a quick check, qmp_block_resize() could similarly block, since it
> > called
> > bdrv_drained_begin(), I'm going to verify it later.
>
> Please do.
>
> Should all these commands support time out?
Yes, I think it is.
Later in v4, I'll add timeout support for qmp_block_resize().
If I find a similar block command in the future, I'll email again.
>
> >> >> > Therefore, we add a timeout parameter for qmp_block_set_io_throttle
> >> >> > to control
> >> >> > its execution duration.
> >> >>
> >> >> What's the QMP reply when a block_set_io_throttle command times out?
> >> >
> >> > The reply is:
> >> > {"id":"libvirt-484","error":{"class":"GenericError","desc":"Blk io
> >> > limits disable timeout"}}
> >>
> >> I find the error message confusing. Suggest "command timed out".
> >
> > This message doesn't provide more details about the error, especially for
> > developers.
> > How about using "command timed out: disable I/O limits"
>
> I don't get what "disable I/O limits" is trying to tell the user. Can
> you explain?
In fact, block_set_io_throttle() has two branches: enable io limits
and disable io limits. If there is a possibility of timeout in both
branches in command, detailed reason may be useful. But now "command timed out"
is enough and I will use it in v4.
>
> >> >> > The default value of timeout is 0, that is infinite wait, consistent
> >> >> > with
> >> >> > previous behavior.
> >> >> >
> >> >> > Signed-off-by: Zhu Yangyang <zhuyangyan...@huawei.com>
> >>
> >> [...]
