Re: [libvirt] [PATCH] Host cpu offline/online removes the cpus available for vms

Thanks for the comments Eric. The offline, removes the entry from the cgroups and all its subcgroups. On Online, I guess kernel does not know till which sub-cgroup it should add the entry. I think that is how cgroup is designed to behave when it lacks the policy knowledge. Let me know what you think. Regards, Shivaprasad G Bhat On Fri, Jan 31, 2014 at 9:58 PM, Eric Blake <eblake(a)redhat.com&gt; wrote: > On 01/31/2014 12:22 AM, Shivaprasad G Bhat wrote: >> Online/Offline operations on the host cpus removes the machine/cpuset.cpus >> which are never added back. The guests with vcpu pinning can fail to boot >> unless the xml is edited. >> >> If the possibility that the offlined cpus are onlined back, the cpuset.cpus can be updated upon start of the guest thus allowing the guests to boot back without >> erroring out. > > Please wrap commit message lines; typically, wrapping less than 70 > characters since 'git log' indents the lines. > >> >> Signed-off-by: Shivaprasad G Bhat <sbhat(a)linux.vnet.ibm.com&gt; >> --- >> src/util/vircgroup.c | 27 +++++++++++++++++---------- >> 1 file changed, 17 insertions(+), 10 deletions(-) >> >> diff --git a/src/util/vircgroup.c b/src/util/vircgroup.c >> index a6d60c5..52575c9 100644 >> --- a/src/util/vircgroup.c >> +++ b/src/util/vircgroup.c >> @@ -72,6 +72,7 @@ typedef enum { >> * before creating subcgroups and >> * attaching tasks >> */ >> + VIR_CGROUP_CPUS_HIERACHY = 1 << 1, /* call virCgroupCpuSetInherit */ > > s/HIERACHY/HIERARCHY/ > > I'm not sure about the technical aspect of this patch, on whether this > is the best approach to deal with the situation. I think the kernel has > caused several issues with how it handles offline cpu vs. cgroups, and > wonder if the fix belongs in the kernel. > > -- > Eric Blake eblake redhat com +1-919-301-3266 > Libvirt virtualization library http://libvirt.org >