Messages in this thread | | | Date | Tue, 05 Aug 2003 13:07:44 +1000 | From | Nick Piggin <> | Subject | Re: [PATCH] O11int for interactivity |
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William Lee Irwin III wrote:
>On Tue, Aug 05, 2003 at 10:56:16AM +1000, Nick Piggin wrote: > >>I'm an IO scheduler type person! What help do you need? I haven't been >>following the thread. >> > >I'm not sure it was in the thread. Basically, the testers appear to >associate skips with changes in writeout and/or readin behavior (either >large amounts of writeout or low amounts of readin), though the effect >of behavior similar to that surrounding a skip doesn't appear to >guarantee a skip. >
Right.
snip vmstat
> >The load IIRC was some kind of io to an IDE disk while xmms played. > >About all I can tell is that when there is a skip, bi is low, but >the converse does not hold. This appears to be independent of io >scheduler (I had them try deadline too), and I'm very unsure what to >make of it. I originally suspected thundering herds from waitqueue >hashing but things appear to contradict that given the low cs rates. >
So yeah it could easily be that for example the cpu scheduler is causing the skip and the low IO rates.
> >I'm collecting instrumentation patches to see what's going on. The >first order of business is probably getting the testers to run with >sleepometer to see if and where they're blocking, but given the io bits >that are observable some elevator instrumentation might help too (and >whatever it takes to figure out if a driver is spinning wildly too!). >
Let me know if you come up with anything significant ;)
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