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authorRik van Riel <riel@redhat.com>2015-03-09 19:12:10 +0300
committerTejun Heo <tj@kernel.org>2015-03-19 21:28:20 +0300
commit34ebe933417e16f46bc30ea77a66e7f30d0cf0f8 (patch)
tree8038b4e6ff84b7b7e3573ce52bd4f48290161ad3 /Documentation/cgroups
parent47b8ea7186aae7f474ec4c98f43eaa8da719cd83 (diff)
downloadlinux-34ebe933417e16f46bc30ea77a66e7f30d0cf0f8.tar.xz
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>
Diffstat (limited to 'Documentation/cgroups')
-rw-r--r--Documentation/cgroups/cpusets.txt10
1 files changed, 8 insertions, 2 deletions
diff --git a/Documentation/cgroups/cpusets.txt b/Documentation/cgroups/cpusets.txt
index f2235a162529..fdf7dff3f607 100644
--- a/Documentation/cgroups/cpusets.txt
+++ b/Documentation/cgroups/cpusets.txt
@@ -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.
------------------------------------------------