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SubjectRe: Linux 2.4.18 Scheduler Bug?
Not that I know of unfortunately.

Vander Velden, Kent wrote:

>Thank you for your response. I was affraid this might be the problem.
>Is there anything that we can do now, i.e. is there a SMP kernel does
>does consider priority?
>
> Thanks.
>
>
>
>
>>-----Original Message-----
>>From: Nick Piggin [mailto:piggin@cyberone.com.au]
>>Sent: Wednesday, September 17, 2003 10:48 PM
>>To: Vander Velden, Kent
>>Subject: Re: Linux 2.4.18 Scheduler Bug?
>>
>>
>>
>>
>>Vander Velden, Kent wrote:
>>
>>
>>
>>>Please CC: responses to my email.
>>>
>>>On two seperate SMP machines I run two instances of two
>>>
>>>
>>different programs, minimin.x and random_simplex. Both
>>instances of random_simplex are niced to 20 on both machines.
>> Both minimin.xand random_simplex are CPU bound processes.
>>On the first machine the processes are allocated CPU as would
>>be expected (data taken from 'top'):
>>
>>
>>>
>>>Linux cn103 2.4.18-18.8.0smp #1 SMP Wed Nov 13 23:11:20 EST
>>>
>>>
>>2002 i686 i686 i386 GNU/Linux
>>
>>
>>>
>>> PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME COMMAND
>>>
>>>25911 f459659 25 0 3452 3452 1032 R 94.3 0.1
>>>
>>>
>>167:13 minimin.x
>>
>>
>>>25903 f459659 25 0 3604 3604 1072 R 93.4 0.1
>>>
>>>
>>168:03 minimin.x
>>
>>
>>>26658 f493418 39 19 5396 5396 4188 R N 5.9 0.2
>>>
>>>
>>0:42 random_simplex
>>
>>
>>>26682 f493418 39 19 5124 5124 4188 R N 5.9 0.1
>>>
>>>
>>0:42 random_simplex
>>
>>
>>>
>>>However, on the second machine they are not:
>>>
>>>
>>>
>>>Linux cn065 2.4.18-18.8.0smp #1 SMP Wed Nov 13 23:11:20 EST
>>>
>>>
>>2002 i686 i686 i386 GNU/Linux
>>
>>
>>>
>>> PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME COMMAND
>>>
>>>26881 f459659 25 0 3452 3452 1032 R 55.6 0.1
>>>
>>>
>>137:03 minimin.x
>>
>>
>>>27630 f493418 39 19 5272 5272 4188 R N 50.6 0.2
>>>
>>>
>>4:37 random_simplex
>>
>>
>>>27654 f493418 39 19 5124 5124 4188 R N 50.6 0.1
>>>
>>>
>>4:37 random_simplex
>>
>>
>>>26873 f459659 25 0 3564 3564 1072 R 44.7 0.1
>>>
>>>
>>137:19 minimin.x
>>
>>
>>>
>>>Renicing the processes has not affect. Restarting the
>>>
>>>
>>processes seems to help. What might be
>>
>>
>>>causing this? Are there any know bugs in the SMP schechuler
>>>
>>>
>>in 2.4.18 that might cause this?
>>
>>
>>The scheduler does not take priority into account when doing SMP
>>balancing.
>>
>>
>>
>>>Is there a workaround or does a more recent kernel fix this?
>>>
>>>
>>>
>>Not as far as I know. I'm working on it in 2.6.
>>
>>
>>
>>
>>
>
>
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