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cpuset, isolcpus: document relationship between cpusets & isolcpus 

Document the subtly changed relationship between cpusets and isolcpus.
Turns out the old documentation did not match the code...

Signed-off-by: Rik van Riel <riel@redhat.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Rik van Riel 2015-03-09 12:12:10 -04:00 committed by Tejun Heo
parent 47b8ea7186
commit 34ebe93341
1 changed files with 8 additions and 2 deletions
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10
Documentation/cgroups/cpusets.txt
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@ -392,8 +392,10 @@ Put simply, it costs less to balance between two smaller sched domains
than one big one, but doing so means that overloads in one of the than one big one, but doing so means that overloads in one of the
two domains won't be load balanced to the other one. two domains won't be load balanced to the other one.
By default, there is one sched domain covering all CPUs, except those By default, there is one sched domain covering all CPUs, including those
marked isolated using the kernel boot time "isolcpus=" argument. marked isolated using the kernel boot time "isolcpus=" argument. However,
the isolated CPUs will not participate in load balancing, and will not
have tasks running on them unless explicitly assigned.
This default load balancing across all CPUs is not well suited for This default load balancing across all CPUs is not well suited for
the following two situations: the following two situations:
@ -465,6 +467,10 @@ such partially load balanced cpusets, as they may be artificially
constrained to some subset of the CPUs allowed to them, for lack of constrained to some subset of the CPUs allowed to them, for lack of
load balancing to the other CPUs. load balancing to the other CPUs.
CPUs in "cpuset.isolcpus" were excluded from load balancing by the
isolcpus= kernel boot option, and will never be load balanced regardless
of the value of "cpuset.sched_load_balance" in any cpuset.
1.7.1 sched_load_balance implementation details. 1.7.1 sched_load_balance implementation details.
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