Messages in this thread | | | Date | Tue, 05 Aug 2003 13:38:34 +1000 | From | Nick Piggin <> | Subject | Re: [PATCH] O11int for interactivity |
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William Lee Irwin III wrote:
>William Lee Irwin III wrote: > >>>Well, I was vaguely hoping a useful way to instrument the io stuff >>>would already be out there. >>> > >On Tue, Aug 05, 2003 at 01:23:08PM +1000, Nick Piggin wrote: > >>Not really. >>For a process doing blocking reads you could measure the time >>from when a process submits a read to when it gets the result. >>I suppose you also need some minimum rate too but I really can't >>see that being the problem here. >> > >I'm at least aware of patches for 2.4.x that log io scheduling >decisions in the driver, which is basically what I was hoping for. > >On a higher level, are you thinking there's some indication the >io schedulers themselves aren't involved? Or that something higher- >level should be instrumented? If so, what? >
Yes thats what I think. Reading an mp3 shouldn't take a lot of disk power, and seeing as its sustaining 20MB/s of writes, and the default AS biases reads quite heavily over writes then it would be very surprising.
Of course some minimum read _latency_ would be required: this could actually be done easily with strace come to think of it.
Maybe some xmms mapped memory is being swapped out? But that would be more of a VM problem.
Get the test run when the mp3 is in ram: if it can't be reproduced then it would be worth looking into further. I guess the process scheduler though.
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