Messages in this thread | | | Date | Tue, 12 Aug 2003 17:18:35 +1000 | From | Nick Piggin <> | Subject | Re: [PATCH] O13int for interactivity |
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Nick Piggin wrote:
> > > Mike Galbraith wrote: > >> At 12:51 PM 8/12/2003 +1000, Nick Piggin wrote: >> >> >>> Rob Landley wrote: >>> >>>> On Tuesday 05 August 2003 06:32, Nick Piggin wrote: >>>> >>>> >>>>> But by employing the kernel's services in the shape of a blocking >>>>> syscall, all sleeps are intentional. >>>> >>>> >>>> >>>> Wrong. Some sleeps indicate "I have run out of stuff to do right >>>> now, I'm going to wait for a timer or another process or something >>>> to wake me up with new work". >>>> >>>> >>>> >>>> Some sleeps indicate "ideally this would run on an enormous ramdisk >>>> attached to gigabit ethernet, but hard drives and internet >>>> connections are just too slow so my true CPU-hogness is hidden by >>>> the fact I'm running on a PC instead of a mainframe." >>> >>> >>> >>> I don't quite understand what you are getting at, but if you don't >>> want to >>> sleep you should be able to use a non blocking syscall. But in some >>> cases >>> I think there are times when you may not be able to use a non >>> blocking call. >>> And if a process is a CPU hog, its a CPU hog. If its not its not. >>> Doesn't >>> matter how it would behave on another system. >> >> >> >> Ah, but there is something there. Take the X and xmms's gl thread >> thingy I posted a while back. (X runs long enough to expire in the >> presence of a couple of low priority cpu hogs. gl thread, which is a >> mondo cpu hog, and normally runs and runs and runs at cpu hog >> priority, suddenly acquires extreme interactive priority, and X, >> which is normally sleepy suddenly becomes permanently runnable at cpu >> hog priority) The gl thread starts sleeping because X isn't getting >> enough cpu to be able to get it's work done and go to sleep. The gl >> thread isn't voluntarily sleeping, and X isn't voluntarily running. >> The behavior change is forced upon both. > > > > It does... It is I tell ya! > > Look, the gl thread is probably _very_ explicitly asking to sleep. No I > don't know how X works, but I have an idea that select is generally used > as an event notification, right? > > Now the gl thread is essentially saying "wait until X finishes the work > I've given it, or I get some other event": ie. "put me to sleep until > this fd becomes readable". > > OK maybe your scenario is a big problem. Its not due to any imagined > semantics in the way things are sleeping. Its due to the scheduler.
And no, X isn't intentionally sleeping. Its being preempted which is obviously not intentional.
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