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Groups > linux.kernel > #1690545
| From | Alexei Potashnik <alexei@purestorage.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH] workqueue: doc change for ST behavior on NUMA systems |
| Date | 2017-07-18 20:20 +0200 |
| Message-ID | <u4Fgd-5OA-3@gated-at.bofh.it> (permalink) |
| Organization | linux.* mail to news gateway |
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> --- Documentation/core-api/workqueue.rst | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/Documentation/core-api/workqueue.rst b/Documentation/core-api/workqueue.rst index ffdec94..3943b5b 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 =========================== -- 1.9.1
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[PATCH] workqueue: doc change for ST behavior on NUMA systems Alexei Potashnik <alexei@purestorage.com> - 2017-07-18 20:20 +0200
Re: [PATCH] workqueue: doc change for ST behavior on NUMA systems Tejun Heo <tj@kernel.org> - 2017-07-18 20:40 +0200
Re: [PATCH] workqueue: doc change for ST behavior on NUMA systems Christoph Hellwig <hch@infradead.org> - 2017-07-18 21:20 +0200
Re: [PATCH] workqueue: doc change for ST behavior on NUMA systems Tejun Heo <tj@kernel.org> - 2017-07-18 21:40 +0200
RE: [PATCH] workqueue: doc change for ST behavior on NUMA systems Alexei Potashnik <alexei@purestorage.com> - 2017-07-18 23:40 +0200
RE: [PATCH] workqueue: doc change for ST behavior on NUMA systems Alexei Potashnik <alexei@purestorage.com> - 2017-07-19 00:30 +0200
[PATCH wq/for-4.13-fixes] workqueue: restore WQ_UNBOUND/max_active==1 to be ordered Tejun Heo <tj@kernel.org> - 2017-07-19 00:50 +0200
Re: [PATCH wq/for-4.13-fixes] workqueue: restore WQ_UNBOUND/max_active==1 to be ordered Tejun Heo <tj@kernel.org> - 2017-07-19 17:30 +0200
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