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List:       linux-kernel
Subject:    Re: scheduling problem test13-pre7
From:       Mike Galbraith <mikeg () wen-online ! de>
Date:       2000-12-31 11:44:22
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On Sun, 31 Dec 2000, Matti Aarnio wrote:

> On Sun, Dec 31, 2000 at 10:42:26AM +0100, Mike Galbraith wrote:
> > Hi,
> > 
> > While running iozone, I notice severe stalls of vmstat output
> > despite vmstat running SCHED_RR and mlockall().
> 
>    Lets eliminate the obvious:
> 
>    - Are you running with IDE disk ?

Yes.

>    - Does   hdparm  /dev/hda(whatever)    report:
> 
> 	/dev/hda:
> 	 unmaskirq    =  0 (off)
> 	 using_dma    =  0 (off)

No.

/dev/hda:
 multcount    =  0 (off)
 I/O support  =  1 (32-bit)
 unmaskirq    =  1 (on)
 using_dma    =  1 (on)
 keepsettings =  1 (on)
 nowerr       =  0 (off)
 readonly     =  0 (off)
 readahead    =  8 (on)
 geometry     = 2482/255/63, sectors = 39876480, start = 0

> 
>    The IKD uses local interrupts, so this isn't necessarily true...

I just did a (mondo) trace covering 8 seconds of kernel time, and
vmstat ran twice.  (Those two times were before I noticed the stall
and started counting down toward 'poke the freeze-frame button')

	-Mike

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