Hi Eric, Came across a thread where the kernel stands not to change the cpuset's behavior during the online->offline->online scenario. https://lkml.org/lkml/2012/5/4/265 Hope fixing this in Libvirt makes more sense now. Regards, Shivaprasad G Bhat On Sat, Feb 1, 2014 at 8:49 AM, Shivaprasad bhat <shivaprasadbhat@xxxxxxxxx> wrote: > 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@xxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxx> >>> --- >>> 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 >> -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list