Re: SCHED_ULE on desktop system

From: Jeff Roberson <jroberson_at_chesapeake.net>
Date: Tue, 2 Oct 2007 01:07:57 -0700 (PDT)
On Mon, 1 Oct 2007, Marc Fonvieille wrote:

> On Mon, Oct 01, 2007 at 11:30:16AM -0700, Jeff Roberson wrote:
>>> I have the same problems as Roman: once I compile something, most of X
>>> applications become slow as hell with lagging screen refresh.  That's on
>>> -CURRENT (with all debug, malloc, invariant things disabled) with ULE
>>> and Xorg 4.3 (I'll test with the legacy scheduler as soon as possible).
>>> This behavior does not occur on 6.2 but with Xorg 7.2, so I really suspect
>>> last Xorg release to be guilty.  Jeff you often mentioned tests on your
>>> laptop, could you check what Xorg version your run?
>>
>> xorg-7.2            X.Org complete distribution metaport
>> xorg-server-1.2.0_2,1 X.Org X server and related programs
>>
>> If you're running very recent current you can try renicing X negatively.
>> If you nice -20 and it doesn't improve then it's probably not the cpu
>> scheduler causing the delay.  What display driver are you using?  How much
>> cpu is X using while you're experiencing the lag?
>>
>
> I tried with _4BSD and it gives the same behavior (I even downgraded
> Xorg to 7.2).  Renicing X does not really help.
>
> I use nvidia or nv driver (nvidia one is a bit less worse).  The lag can
> even appears with 4% of CPU usage according to top(1).
> Thanks to your remarks and my tests, I'm now sure it's scheduler
> independent.  It seems 7-CURRENT is slower than 6.X regarding I/O :(
> For info the box is a 1.2GHz Athlon with 1GB of RAM and swap is never
> used.

Can you try with ULE and the attached diff?  sched_yield() behavior 
changed between 6.x and 7-CURRENT.  This has been referenced in other bug 
reports.  Please let me know if this helps.

Thanks,
Jeff

>
> -- 
> Marc
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Received on Tue Oct 02 2007 - 06:05:28 UTC

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