Re: SCHED_ULE on desktop system

From: Jeff Roberson <jroberson_at_chesapeake.net>
Date: Mon, 17 Sep 2007 14:22:29 -0700 (PDT)
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:

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
>
Received on Mon Sep 17 2007 - 19:19:36 UTC

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