Hi, if a domain is paused (= not scheduled), its process that keeps otherwise kicking /dev/watchdog and (thusly the hypervisor) "freezes" too. Should pausing a domain suspend (or "inactivate") its watchdog_timers? (I believe this must have been considered and the answer is "you shouldn''t do that", but a confirmation/refutation would be nice.) Thanks L. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
>>> On 13.10.11 at 15:41, Laszlo Ersek <lersek@redhat.com> wrote: > if a domain is paused (= not scheduled), its process that keeps > otherwise kicking /dev/watchdog and (thusly the hypervisor) "freezes" > too. Should pausing a domain suspend (or "inactivate") its watchdog_timers?I would say yes it should. And you say it doesn''t?> (I believe this must have been considered and the answer is "you > shouldn''t do that", but a confirmation/refutation would be nice.)If a domain gets paused from the tools stack, it''s not very reasonable to expect the operator there to know whether a particular domain has a watchdog timer activated. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On 10/13/11 16:21, Jan Beulich wrote:>>>> On 13.10.11 at 15:41, Laszlo Ersek<lersek@redhat.com> wrote: >> if a domain is paused (= not scheduled), its process that keeps >> otherwise kicking /dev/watchdog and (thusly the hypervisor) "freezes" >> too. Should pausing a domain suspend (or "inactivate") its watchdog_timers? > > I would say yes it should. And you say it doesn''t?I must have missed a changeset (or a hunk?) related to pausing: https://bugzilla.redhat.com/show_bug.cgi?id=742880#c1 I backported 21529 from xen-unstable to the RHEL-5 hypervisor version, and Igor tested pausing a Fedora 16 HVM guest. The domU was destroyed while it was paused. Thanks! L. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On 13/10/2011 14:41, "Laszlo Ersek" <lersek@redhat.com> wrote:> Hi, > > if a domain is paused (= not scheduled), its process that keeps > otherwise kicking /dev/watchdog and (thusly the hypervisor) "freezes" > too. Should pausing a domain suspend (or "inactivate") its watchdog_timers? > > (I believe this must have been considered and the answer is "you > shouldn''t do that", but a confirmation/refutation would be nice.)Yes, the ability to pause a domain from the toolstack command line was added way back in the beginning largely because... Well, because it could be done, and it was easy! It''s not actually a very good idea. You won''t actually find the toolstack itself automatically pausing a domain in very many places at all -- most places where it does are debug/diagnostic code, or where a domain is about to be destroyed anyway. So, yes, in short: don''t do that! :-) -- Keir> Thanks > L. > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On 13/10/2011 15:38, "Laszlo Ersek" <lersek@redhat.com> wrote:> On 10/13/11 16:21, Jan Beulich wrote: >>>>> On 13.10.11 at 15:41, Laszlo Ersek<lersek@redhat.com> wrote: >>> if a domain is paused (= not scheduled), its process that keeps >>> otherwise kicking /dev/watchdog and (thusly the hypervisor) "freezes" >>> too. Should pausing a domain suspend (or "inactivate") its watchdog_timers? >> >> I would say yes it should. And you say it doesn''t? > > I must have missed a changeset (or a hunk?) related to pausing: > > https://bugzilla.redhat.com/show_bug.cgi?id=742880#c1 > > I backported 21529 from xen-unstable to the RHEL-5 hypervisor version, > and Igor tested pausing a Fedora 16 HVM guest. The domU was destroyed > while it was paused.You are just as likely to upset a watchdog implemented entirely internally to the guest, and which we have no chance to disable/suspend when a domain is paused. Domain pausing from the dom0 command line really doesn''t have a production use case afaik -- just don''t do it is my helpful suggestion. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On 10/13/11 16:56, Keir Fraser wrote:> On 13/10/2011 15:38, "Laszlo Ersek"<lersek@redhat.com> wrote: > >> On 10/13/11 16:21, Jan Beulich wrote: >>>>>> On 13.10.11 at 15:41, Laszlo Ersek<lersek@redhat.com> wrote: >>>> if a domain is paused (= not scheduled), its process that keeps >>>> otherwise kicking /dev/watchdog and (thusly the hypervisor) "freezes" >>>> too. Should pausing a domain suspend (or "inactivate") its watchdog_timers? >>> >>> I would say yes it should. And you say it doesn''t? >> >> I must have missed a changeset (or a hunk?) related to pausing: >> >> https://bugzilla.redhat.com/show_bug.cgi?id=742880#c1 >> >> I backported 21529 from xen-unstable to the RHEL-5 hypervisor version, >> and Igor tested pausing a Fedora 16 HVM guest. The domU was destroyed >> while it was paused. > > You are just as likely to upset a watchdog implemented entirely internally > to the guest, and which we have no chance to disable/suspend when a domain > is paused. Domain pausing from the dom0 command line really doesn''t have a > production use case afaik -- just don''t do it is my helpful suggestion.Thank you both for the answers. L. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel