Re: [libvirt] [PATCH] Use unsigned timeout in cmdMigrateSetMaxDowntime
John Ferlan <jferlan(a)redhat.com> wrote on 07/10/2017 06:41:34 AM:
From: John Ferlan <jferlan(a)redhat.com>
To: Scott Garfinkle <seg(a)us.ibm.com>, libvir-list(a)redhat.com
Date: 07/10/2017 06:41 AM
Subject: Re: [libvirt] [PATCH] Use unsigned timeout in
cmdMigrateSetMaxDowntime
On 06/27/2017 11:19 AM, Scott Garfinkle wrote:
> While looking to implement a migrate-getmaxdowntime command (coming),
> I noticed that the setmaxdowntime is incorrectly looking at its
> parameter as a signed longlong. Not sure how that got past gcc, but
> here's a simple patch to make the command line parsing and the
parameter
to
> the worker functions all have the correct (unsigned) type.
>
> Signed-off-by: Scott Garfinkle <seg(a)us.ibm.com>
> ---
> tools/virsh-domain.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
"For some commands" allowing a -1 provides a mechanism to set an almost
infinite time without having to type such a large value. Still in this
case since, the "downtime < 1" check immediately follows it seems that
wouldn't be the case here!
Yes, and maybe removing that check would have been a
better alternative?
Still, thanks.
Looking at QEMU code briefly - I do note the QEMU set downtime (and
speed) commands that end up getting called are listed as "deprecated" in
favor of migrate-set-parameters (downtime-limit and max-bandwidth, since
QEMU 2.8). So while you're at thinking about a getmaxdowntime type
functionality maybe you'd want to give that a go as well (of course
you'd have to add capabilities to detect when it was implemented using
set-parameters)...
Thanks for pointing that out. So, I have patches to implement the
get-maxdowntime, which would seem to be a separate but related effort.
Being a newcomer to the code, I'll what are probably obvious questions: is
the concern that qemu will eventually just stop providing that interface?
Or, is there something inherently useful about changing the set-*
commands? Otherwise, I'm not sure what the value to the code is of
changing the already-working set commands.
regards, Scott Garfinkle
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