Messages in this thread | | | Subject | Re: [PATCH 4/4] sched: add hooks for workqueue | From | Peter Zijlstra <> | Date | Mon, 31 May 2010 12:05:58 +0200 |
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On Mon, 2010-05-31 at 11:58 +0200, Tejun Heo wrote: > Hello, Peter. > > On 05/31/2010 10:01 AM, Peter Zijlstra wrote: > > On Thu, 2010-05-13 at 12:48 +0200, Tejun Heo wrote: > >> Concurrency managed workqueue needs to know when workers are going to > >> sleep and waking up, and, when a worker goes to sleep, be able to wake > >> up another worker to maintain adequate concurrency. This patch > >> introduces PF_WQ_WORKER to identify workqueue workers and adds the > >> following two hooks. > >> > >> * wq_worker_waking_up(): called when a worker is woken up. > >> > >> * wq_worker_sleeping(): called when a worker is going to sleep and may > >> return a pointer to a local task which should be woken up. The > >> returned task is woken up using try_to_wake_up_local() which is > >> simplified ttwu which is called under rq lock and can only wake up > >> local tasks. > > > > This changelog seems to lack explanation for why you need the wakeup > > callback. > > Because cmwq "needs to know when workers are going to sleep and waking > up, and, when a worker goes to sleep, be able to wake up another > worker to maintain adequate concurrency".
That again only explains what you use the sleep hook for, not what you want to use the wakeup hook for (putting a worker to sleep when there are now 2 runnable seems like a good use).
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