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authorAlexei Potashnik <alexei@purestorage.com>2017-07-18 21:12:53 +0300
committerTejun Heo <tj@kernel.org>2017-07-18 21:34:53 +0300
commit0e0cafcda83951bb0b438d78a4216ae94483cba6 (patch)
tree8cac8a0a29c1577cd026e45b0b39b55ec225edc0 /Documentation/core-api
parentbef85bd7db2669291e33c59875fae33d24c11da3 (diff)
downloadlinux-0e0cafcda83951bb0b438d78a4216ae94483cba6.tar.xz
workqueue: doc change for ST behavior on NUMA systems
NUMA rework of workqueue made the combination of max_active of 1 and WQ_UNBOUND insufficient to guarantee ST behavior system wide. alloc_ordered_queue should now be used instead. Signed-off-by: Alexei Potashnik <alexei@purestorage.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'Documentation/core-api')
-rw-r--r--Documentation/core-api/workqueue.rst10
1 files changed, 7 insertions, 3 deletions
diff --git a/Documentation/core-api/workqueue.rst b/Documentation/core-api/workqueue.rst
index ffdec94fbca1..3943b5bfa8cf 100644
--- a/Documentation/core-api/workqueue.rst
+++ b/Documentation/core-api/workqueue.rst
@@ -243,11 +243,15 @@ throttling the number of active work items, specifying '0' is
recommended.
Some users depend on the strict execution ordering of ST wq. The
-combination of ``@max_active`` of 1 and ``WQ_UNBOUND`` is used to
-achieve this behavior. Work items on such wq are always queued to the
-unbound worker-pools and only one work item can be active at any given
+combination of ``@max_active`` of 1 and ``WQ_UNBOUND`` used to
+achieve this behavior. Work items on such wq were always queued to the
+unbound worker-pools and only one work item could be active at any given
time thus achieving the same ordering property as ST wq.
+In the current implementation the above configuration only guarantees
+ST behavior within a given NUMA node. Instead alloc_ordered_queue should
+be used to achieve system wide ST behavior.
+
Example Execution Scenarios
===========================