Messages in this thread | | | Date | Wed, 2 Jul 2008 15:27:09 +0100 (BST) | From | Hugh Dickins <> | Subject | Re: [Ksummit-2008-discuss] Delayed interrupt work, thread pools |
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On Wed, 2 Jul 2008, Benjamin Herrenschmidt wrote: > On Tue, 2008-07-01 at 20:39 -0500, Dean Nelson wrote: > > As Robin, mentioned XPC manages a pool of kthreads that can (for performance > > reasons) be quickly awakened by an interrupt handler and that are able to > > block for indefinite periods of time. > > > > In drivers/misc/sgi-xp/xpc_main.c you'll find a rather simplistic attempt > > at maintaining this pool of kthreads. > > > > The kthreads are activated by calling xpc_activate_kthreads(). Either idle > > kthreads are awakened or new kthreads are created if a sufficent number of > > idle kthreads are not available. > > > > Once finished with current 'work' a kthread waits for new work by calling > > wait_event_interruptible_exclusive(). (The call is found in > > xpc_kthread_waitmsgs().) > > > > The number of idle kthreads is limited as is the total number of kthreads > > allowed to exist concurrently. > > > > It's certainly not optimal in the way it maintains the number of kthreads > > in the pool over time, but I've not had the time to spare to make it better. > > > > I'd love it if a general mechanism were provided so that XPC could get out > > of maintaining its own pool. > > Thanks. That makes one existing in-tree user and a one likely WIP user, > probably enough to move forward :-) > > I'll look at your implementation and discuss internally see what our > specific needs in term of number of threads etc... look like. > > I might come up with something simple first (ie, generalizing your > current implementation for example) and then look at some smarter > management of the thread pools.
Do the pdflush daemons (from mm/pdflush.c) provide another example?
Hugh
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