[PATCH v5 0/5] CPU hotplug, cpusets, suspend/resume: Fixes,cleanups and optimizations

[Srivatsa S. Bhat]

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).

--
 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      cpusets: Remove/update outdated comments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(-)



Thanks,
Srivatsa S. Bhat
IBM Linux Technology Center

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/