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authorAdrian Freund <adrian@freund.io>2020-04-07 15:05:25 +0200
committerJonathan Corbet <corbet@lwn.net>2020-04-21 13:38:27 -0600
commit7b9121040d83eb9e332f7dbc140eca17643d3586 (patch)
tree6db66942ecd373f683a8ac101f7d7dcab250ee58
parent5af438d0dcdbdbc1da4f3abcdf08fe9b1291ca02 (diff)
Documentation: scheduler: fix outdated information on sched groups
The documentation claims that two sched groups must not overlap. This is no longer true, as overlapping sched groups are used on NUMA systems. This change has been introduced by commit e3589f6c81e47 and was documented by an in-code comment in commit 35a566e6e8a18. Signed-off-by: Adrian Freund <adrian@freund.io> Link: https://lore.kernel.org/r/20200407130525.76663-1-adrian@freund.io Signed-off-by: Jonathan Corbet <corbet@lwn.net>
-rw-r--r--Documentation/scheduler/sched-domains.rst10
1 files changed, 6 insertions, 4 deletions
diff --git a/Documentation/scheduler/sched-domains.rst b/Documentation/scheduler/sched-domains.rst
index f7504226f445..5c4b7f4f0062 100644
--- a/Documentation/scheduler/sched-domains.rst
+++ b/Documentation/scheduler/sched-domains.rst
@@ -19,10 +19,12 @@ CPUs".
Each scheduling domain must have one or more CPU groups (struct sched_group)
which are organised as a circular one way linked list from the ->groups
pointer. The union of cpumasks of these groups MUST be the same as the
-domain's span. The intersection of cpumasks from any two of these groups
-MUST be the empty set. The group pointed to by the ->groups pointer MUST
-contain the CPU to which the domain belongs. Groups may be shared among
-CPUs as they contain read only data after they have been set up.
+domain's span. The group pointed to by the ->groups pointer MUST contain the CPU
+to which the domain belongs. Groups may be shared among CPUs as they contain
+read only data after they have been set up. The intersection of cpumasks from
+any two of these groups may be non empty. If this is the case the SD_OVERLAP
+flag is set on the corresponding scheduling domain and its groups may not be
+shared between CPUs.
Balancing within a sched domain occurs between groups. That is, each group
is treated as one entity. The load of a group is defined as the sum of the