Re: SCHED_ULE on desktop system

From: Roman Bogorodskiy <novel_at_FreeBSD.org>
Date: Tue, 18 Sep 2007 19:52:45 +0400
  Jeff Roberson wrote:

> On Mon, 17 Sep 2007, Roman Bogorodskiy wrote:
> 
>>  Roman Bogorodskiy wrote:
>> 
>>>   Jeff Roberson wrote:
>>> 
>>>> On Sun, 16 Sep 2007, Roman Bogorodskiy wrote:
>>>> 
>>>>>  Jeff Roberson wrote:
>>>>> 
>>>>>> This is contrary to the experiences of many others.  Can you send me 
>>>>>> your
>>>>>> dmesg?  There may be something about your particular hardware that is
>>>>>> triggering a bug.  ULE is definitely designed to be responsive on the
>>>>>> desktop.
>>>>> 
>>>>> Thanks for the quick answer!
>>>>> 
>>>>> Here's my dmesg: http://people.freebsd.org/~novel/misc/dmesg.txt
>>>> 
>>>> Roman,
>>>> 
>>>> The enclosed patch helps things on my system, however, there are still 
>>>> some
>>>> delays due to IO issues.  Let me know if this helps.
>>> 
>>> This patch seems to make my system react faster. However I need some
>>> time to test it more carefully.
>> 
>> It looks like it's not really so, it's still very slow under load. :(
> 
> Roman,
> 
> Can you please verify that you are not swapping.  If you are, try the patch 
> that I sent.  Otherwise, can you try getting KTR_SCHED output for me?  Put 
> the following in your kernel config file:

Swap is not used at all (and I don't use WITNESS, etc). I will run
through the steps you wrote ASAP.

> options         KTR
> options         KTR_COMPILE=KTR_SCHED
> options         KTR_MASK=KTR_SCHED
> options         KTR_ENTRIES=65536
> 
> 
> Then run the load that exhibits the problem.  compile, play a movie, etc. 
> wait for a particularly bad pause and then run the following:
> 
> sysctl debug.ktr.mask=0 && ktrdump -ct > out && sysctl 
> debug.ktr.mask=536870
> 
> It's best to have the command ready in a shell so you can run it in the 
> closest proximity to the incident.  Then gzip the results and email them to 
> me.
> 
> On my system I'm not able to play a movie while running buildworld due to 
> long disk waits.  However, if I use a dvd driver, mplayer and x windows 
> both get enough cpu time to play the movie skip free.  So this is not a cpu 
> scheduler problem as such.  IO scheduling does feel less responsive than 
> 6.x but I have not done a side by side comparison.
> 
> Jeff
> 
>> 
>>>> Thanks,
>>>> Jeff
>>>> 
>>>>> 
>>>>> Roman Bogorodskiy
>>>>> 
>>> 
>>> 
>>> Roman Bogorodskiy
>> 
>> 
>> Roman Bogorodskiy
>> 
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Roman Bogorodskiy

Received on Tue Sep 18 2007 - 13:52:28 UTC

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