Bug 523127
| Summary: | [RHEL-6 Xen]: Hotplugging vcpus to a 64-bit domU doesn't work | |||
|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 6 | Reporter: | Chris Lalancette <clalance> | |
| Component: | udev | Assignee: | Harald Hoyer <harald> | |
| Status: | CLOSED CURRENTRELEASE | QA Contact: | Jan Ščotka <jscotka> | |
| Severity: | medium | Docs Contact: | ||
| Priority: | high | |||
| Version: | 6.0 | CC: | berrange, dkovalsk, drjones, gcosta, harald, itamar, jane.lv, jeremy, jscotka, jvillalo, kernel-maint, luyu, markmc, pbonzini, pknirsch, virt-maint, xen-maint | |
| Target Milestone: | rc | |||
| Target Release: | --- | |||
| Hardware: | All | |||
| OS: | Linux | |||
| Whiteboard: | ||||
| Fixed In Version: | udev-147-1.fc13 | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | ||
| Clone Of: | 499611 | |||
| : | 630947 (view as bug list) | Environment: | ||
| Last Closed: | 2010-11-10 21:48:56 UTC | Type: | --- | |
| Regression: | --- | Mount Type: | --- | |
| Documentation: | --- | CRM: | ||
| Verified Versions: | Category: | --- | ||
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | ||
| Cloudforms Team: | --- | Target Upstream Version: | ||
| Embargoed: | ||||
| Bug Depends On: | 499611 | |||
| Bug Blocks: | 630947, 633349 | |||
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Description
Chris Lalancette
2009-09-14 08:24:06 UTC
This request was evaluated by Red Hat Product Management for inclusion in a Red Hat Enterprise Linux major release. Product Management has requested further review of this request by Red Hat Engineering, for potential inclusion in a Red Hat Enterprise Linux Major release. This request is not yet committed for inclusion. Somewhat related to this, there was recently a bug with bare-metal hotplug: https://bugzilla.redhat.com/show_bug.cgi?id=523505 So, we might be able to ask the people who worked on that what the expected behavior is; is the kernel responsible for doing the hotplug in the end, or is it userland? Chris Lalancette See this comment: --- Additional comment from jeremy on 2009-05-11 13:36:24 EDT --- It needs some usermode support to work. It will generate uevents, and a script is needed to do the actual onlining. You can see that the cpus will appear and disappear in /sys/devices/system/cpu/present. This is a behaviour change from older Xen kernels which did this internally, but seemed like the better approach. So it seems we really need the udev rule now for CPU hotplugging. The rule also looks dead easy and simple, so granting Devel ACK for this. Thanks & regards, Phil There were patches posted recently for pv_ops kernel to support hotplug: http://lists.xensource.com/archives/html/xen-devel/2009-11/msg00657.html http://lists.xensource.com/archives/html/xen-devel/2009-11/msg00658.html I'm not quite sure if they were accepted or not, but worth looking into. We now have at least 2 solutions for this; we just need to figure out which one we want to use for RHEL-6. Chris Lalancette please test udev-147-1.fc13 https://koji.fedoraproject.org/koji/buildinfo?buildID=140950 (In reply to comment #6) > There were patches posted recently for pv_ops kernel to support hotplug: > > http://lists.xensource.com/archives/html/xen-devel/2009-11/msg00657.html > http://lists.xensource.com/archives/html/xen-devel/2009-11/msg00658.html > > I'm not quite sure if they were accepted or not, but worth looking into. We > now have at least 2 solutions for this; we just need to figure out which one we > want to use for RHEL-6. This pertains to physical (host) cpu hotplug, not domain vcpu hotplug, which is quite distinct. I don't think its relevant to this bug. (In reply to comment #8) > (In reply to comment #6) > > There were patches posted recently for pv_ops kernel to support hotplug: > > > > http://lists.xensource.com/archives/html/xen-devel/2009-11/msg00657.html > > http://lists.xensource.com/archives/html/xen-devel/2009-11/msg00658.html > > > > I'm not quite sure if they were accepted or not, but worth looking into. We > > now have at least 2 solutions for this; we just need to figure out which one we > > want to use for RHEL-6. > > This pertains to physical (host) cpu hotplug, not domain vcpu hotplug, which is > quite distinct. I don't think its relevant to this bug. Yeah, you are right. I mis-read the upstream posting. Sorry about that! Chris Lalancette udev-145-14.fc12 has been pushed to the Fedora 12 stable repository. If problems still persist, please make note of it in this bug report. Fixed in 'udev-147-1.fc13'. 'udev-147-2.1.el6' included in compose 'RHEL6.0-20091216.nightly'. Moving to ON_QA. I tested on latest rhel6 64b PV xen domu with latest rhel5 dom0 rhel6 packages: kernel-2.6.32-70.el6.x86_64 udev-147-2.29.el6.x86_64 'xm vcpu-set' unfortunately has no affect on /sys/devices/system/cpu/present. We're probably missing something from upstream in the kernel, or possibly something broke in the kernel, because I'm pretty sure it used to work (so a kernel issue). However, I can online/offline the guest cpus with echo 0|1 > /sys/devices/system/cpu/cpu?/online fine. Also confirmed that vcpu hot plug is working on rhel6 pv guests. It didn't work for me before (comment 15), because the xen userspace has regressed. I was using -115 rather than -105. I'm opening a bug to xen userspace for that issue, but I concur that this bug is verified. Note the expected behavior is a default maxvcpus == vcpus originally defined. It's possible to add more if you set the maxvcpus param in your config to something higher, such as 16. Okay, so this bug seems to be repaired. test of changing numbers of cpus PASS Red Hat Enterprise Linux 6.0 is now available and should resolve the problem described in this bug report. This report is therefore being closed with a resolution of CURRENTRELEASE. You may reopen this bug report if the solution does not work for you. |