Messages in this thread | | | Date | Fri, 13 Mar 2015 09:38:27 +0800 | From | Lai Jiangshan <> | Subject | Re: [PATCH 4/4] workqueue: Allow modifying low level unbound workqueue cpumask |
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On 03/13/2015 01:42 AM, Christoph Lameter wrote: > On Thu, 12 Mar 2015, Lai Jiangshan wrote: > >> The per-nodes' pwqs are mandatorily controlled by the low level cpumask, while >> the default pwq ignores the low level cpumask when (and ONLY when) the cpumask set >> by the user doesn't overlap with the low level cpumask. In this case, we can't >> apply the empty cpumask to the default pwq, so we use the user-set cpumask >> directly. > > I am wondering now why we have two cpumasks?
What's your meaning? which two cpumask?
The per-nodes' pwqs' cpumask and the default pwq's cpumask? They refer to different pool, so they have different cpumask.
1) If the per-nodes' pwqs exist, they were controlled by A (A = user-set-cpumask & possible-cpus-of-the-node). Now after this patch, they are controlled by B (B = A & the-low-level-cpumak).
if A is empty or B is empty, we used default pwq for the node.
2) The default pwq is different, it was controlled by C (C = user-set-cpumask), and after this patch, it will be controlled by D (D = user-set-cpumask(C) & the-low-level-cpumask), But D may be empty, we can't have a default pwq with empty cpumask, so we have use C instead in this case.
> A script can just interate > through the work queues if we want to set them all right? Then we do not > have to deal with the conflict between the settings in the kernel.
wq->unbound_attrs->cpumask and the-low-level-cpumask can be set by users. they may be set different or even non-intersect, the non-intersect case is not real conflict, but it is possible, we have to handle it.
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