Messages in this thread | | | Date | Sun, 20 May 2012 19:28:03 +0530 | From | "Srivatsa S. Bhat" <> | Subject | Re: [PATCH v5 0/5] CPU hotplug, cpusets, suspend/resume: Fixes, cleanups and optimizations |
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Hi Peter,
Did you get a chance to take a look at this patchset?
(I have added a summary of the changes between the versions below.)
Thanks a lot!
On 05/17/2012 10:29 PM, Srivatsa S. Bhat wrote:
> Currently the kernel doesn't handle cpusets properly during suspend/resume. > After a resume, all non-root cpusets end up having only 1 cpu (the boot cpu), > causing massive performance degradation of workloads. One major user of cpusets > is libvirt, which means that after a suspend/hibernation cycle, all VMs > suddenly end up running terribly slow! > > Also, the kernel moves the tasks from one cpuset to another during CPU hotplug > in the suspend/resume path, leading to a task-management nightmare after > resume. > > Patch 1 fixes this by keeping cpusets unmodified in the suspend/resume path. > But to ensure we don't trip over, it keeps the sched domains updated during > every CPU hotplug in the s/r path. > This is a long standing issue and we need to fix up stable kernels too. > > The rest of the patches in the series are mostly cleanups/optimizations > (except patch 4 which is a non-critical bug fix). >
Changelog:
v5 : Don't do explicit save/restore of cpusets' cpu masks during s/r, to avoid the overhead of a new per-cpuset cpu mask to help with that. Also, ensure that the sched domains are updated on each hotplug. The s/r fix (patch 1) is now distinct from the cleanups (patches 2-5).
v4 : (Never had this version. I skipped from v3 to v5 accidentally).
v3 : Explicitly save and restore cpusets' cpu masks during s/r. Don't alter the semantics of regular cpu hotplug. http://thread.gmane.org/gmane.linux.kernel/1296339
v2 : http://thread.gmane.org/gmane.linux.documentation/4805/
v1 : thread.gmane.org/gmane.linux.kernel/1250097/
> -- > Srivatsa S. Bhat (5): > CPU hotplug, cpusets, suspend: Don't modify cpusets during suspend/resume > cpusets, hotplug: Implement cpuset tree traversal in a helper function > cpusets, hotplug: Restructure functions that are invoked during hotplug > cpusets: Update tasks' cpus_allowed mask upon updates to root cpuset > cpusets: Remove/update outdated comments > > > include/linux/cpuset.h | 4 + > kernel/cpuset.c | 161 +++++++++++++++++++++++++++++++++++------------- > kernel/sched/core.c | 44 +++++++++++-- > 3 files changed, 159 insertions(+), 50 deletions(-)
Regards, Srivatsa S. Bhat
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