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Commit 34ebe933 authored by Rik van Riel's avatar Rik van Riel Committed by Tejun Heo
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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: default avatarRik van Riel <riel@redhat.com>
Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
Acked-by: default avatarZefan Li <lizefan@huawei.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 47b8ea71

Documentation/cgroups/cpusets.txt

+8 −2
Original line number Diff line number Diff line
@@ -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

two domains won't be load balanced to the other one.



By default, there is one sched domain covering all CPUs, except those

marked isolated using the kernel boot time "isolcpus=" argument.

By default, there is one sched domain covering all CPUs, including those

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

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

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.

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