lkml.org 
[lkml]   [2003]   [Aug]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] O11int for interactivity


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.


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:47    [W:0.063 / U:0.792 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site