Messages in this thread | | | Date | Thu, 01 Oct 2009 19:06:29 +0200 | From | Avi Kivity <> | Subject | Re: [RFC PATCHSET] workqueue: implement concurrency managed workqueue |
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On 10/01/2009 06:55 PM, Tejun Heo wrote: >> For kvm, we don't want to force a specific scheduling class for vcpu >> threads, so we'd need infrastructure to create a new scheduling class >> out of an existing one to hook the two callbacks. Seems like quite a >> lot of work, for something that is orthogonal to scheduling. >> >> Tejun, would preempt notifiers work for your workqueues? see bottom of >> include/linux/preempt.h. >> > I considered that but the thing is workqueue needs to know when a > thread wakes up not when it gets scheduled. Of course we can add > another notifier op and call it from try_to_wake_up() but I really > didn't want to add yet another hook in a very hot path which will only > be useful for very small number of tasks but yet has to be called for > every operation and the sched_class mechanism means that we already > have hooks at all the interesting spots, so I think it's better to > make use of them instead of adding another set of callbacks. >
Right, it's a subtle difference that makes p_n unusable for you.
-- Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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