Messages in this thread | | | Subject | Re: [PATCH 0/4] CPU hotplug, cpusets: Fix CPU online handling related to cpusets | From | Peter Zijlstra <> | Date | Mon, 20 Feb 2012 13:49:05 +0100 |
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On Fri, 2012-02-17 at 17:45 +0530, Srivatsa S. Bhat wrote:
> > Trivially removing CPU_TASKS_FROZEN as shown below doesn't look right to me: > > > > --- > > > > kernel/sched/core.c | 4 ++-- > > 1 files changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > > index 5255c9d..43a166e 100644 > > --- a/kernel/sched/core.c > > +++ b/kernel/sched/core.c > > @@ -6729,7 +6729,7 @@ int __init sched_create_sysfs_power_savings_entries(struct device *dev) > > static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action, > > void *hcpu) > > { > > - switch (action & ~CPU_TASKS_FROZEN) { > > + switch (action) { > > case CPU_ONLINE: > > case CPU_DOWN_FAILED: > > cpuset_update_active_cpus(); > > @@ -6742,7 +6742,7 @@ static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action, > > static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action, > > void *hcpu) > > { > > - switch (action & ~CPU_TASKS_FROZEN) { > > + switch (action) { > > case CPU_DOWN_PREPARE: > > cpuset_update_active_cpus(); > > return NOTIFY_OK; > > > > > > IMO, irrespective of whether we keep cpusets unaware of all CPU Hotplug or > > only unaware of the CPU hotplug in the suspend/resume path, I feel the > > scheduler should always know the true state of the system, ie., offline CPUs > > must not be part of any sched domain, at any point in time.
That's really not a problem as long as they're not in the active mask.
> > At the moment, I am exploring several ways to achieve this (I can think of 2 > > ways at the moment, will see which one is better). But in case this approach > > itself seems wrong for any reason, please let me know.
Have you actually tried the simple patch?
Calling partition_sched_domains() like you do doesn't seem right, it completely ignores cpusets, it will make certain cpuset configurations mis-behave.
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