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author | Tejun Heo <tj@kernel.org> | 2010-06-08 23:40:36 +0400 |
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committer | Tejun Heo <tj@kernel.org> | 2010-06-08 23:40:36 +0400 |
commit | 3a101d0548e925ab16ca6aaa8cf4f767d322ddb0 (patch) | |
tree | b90d8c5f2efe30fcfa49a00fdea037567c6cd46f /Documentation/email-clients.txt | |
parent | 50a323b73069b169385a8ac65633dee837a7d13f (diff) | |
download | linux-3a101d0548e925ab16ca6aaa8cf4f767d322ddb0.tar.xz |
sched: adjust when cpu_active and cpuset configurations are updated during cpu on/offlining
Currently, when a cpu goes down, cpu_active is cleared before
CPU_DOWN_PREPARE starts and cpuset configuration is updated from a
default priority cpu notifier. When a cpu is coming up, it's set
before CPU_ONLINE but cpuset configuration again is updated from the
same cpu notifier.
For cpu notifiers, this presents an inconsistent state. Threads which
a CPU_DOWN_PREPARE notifier expects to be bound to the CPU can be
migrated to other cpus because the cpu is no more inactive.
Fix it by updating cpu_active in the highest priority cpu notifier and
cpuset configuration in the second highest when a cpu is coming up.
Down path is updated similarly. This guarantees that all other cpu
notifiers see consistent cpu_active and cpuset configuration.
cpuset_track_online_cpus() notifier is converted to
cpuset_update_active_cpus() which just updates the configuration and
now called from cpuset_cpu_[in]active() notifiers registered from
sched_init_smp(). If cpuset is disabled, cpuset_update_active_cpus()
degenerates into partition_sched_domains() making separate notifier
for !CONFIG_CPUSETS unnecessary.
This problem is triggered by cmwq. During CPU_DOWN_PREPARE, hotplug
callback creates a kthread and kthread_bind()s it to the target cpu,
and the thread is expected to run on that cpu.
* Ingo's test discovered __cpuinit/exit markups were incorrect.
Fixed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Menage <menage@google.com>
Diffstat (limited to 'Documentation/email-clients.txt')
0 files changed, 0 insertions, 0 deletions