Re: High latencies on MPC5200 with patch-2.6.24-rc5-rt1

[Juergen Beisert <jbe@pengutronix.de>]

On Thursday 10 January 2008 14:17, Wolfgang Grandegger wrote:
> Hi Robert,
>
> Robert Schwebel wrote:
> > Wolfgang,
> >
> > On Wed, Jan 09, 2008 at 11:51:07PM +0100, Robert Schwebel wrote:
> >> Throwing in the versions from 2.6.23.3-rt5 doesn't help, the effect
> >> stays the same. So I assume it is a side effect.
> >
> > Can you test the following patch by John Stulz (thanks to John for the
> > quick help on irc!), which fixes the issues on my board:
> >
> > ----------8<----------
> > Index: linux-2.6.24-rc5/arch/powerpc/kernel/time.c
> > ===================================================================
> > --- linux-2.6.24-rc5.orig/arch/powerpc/kernel/time.c
> > +++ linux-2.6.24-rc5/arch/powerpc/kernel/time.c
> > @@ -773,7 +773,7 @@ void update_vsyscall(struct timespec *wa
> >  	stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC;
> >  	do_div(stamp_xsec, 1000000000);
> >  	stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC;
> > -	update_gtod(clock->cycle_last, stamp_xsec, t2x);
> > +	update_gtod(clock->cycle_last-clock->cycle_accumulated, stamp_xsec,
> > t2x); }
> >
> >  void update_vsyscall_tz(void)
> > ----------8<----------
> >
> > With this patch ontop of 2.6.24-rc5-rt1 plus the board support patches
> > for the phyCORE-MPC5200B-tiny, I get this result from cyclictest, again
> > under "(while true; do hackbench 10; done) &" load:
> >
> > T: 0 (  867) P:80 I:   10000 C:  105002 Min:      31 Act:      48 Avg:   
> >   51 Max:      92
>
> Unfortunately, it doesn't really help on my Icecube board.
>
> bash-3.00# ./cyclictest -n -p80 -i1000
> 129.85 93.18 38.05 4/45 6354
> 130.41 162.23 83.05 3/49 8395
> T: 0 ( 4621) P:80 I:1000 C: 477097 Min:     25 Act:   64 Avg:   67 Max:
>     286
>
> bash-3.00# ./hackbench 10
> Time: 95.402
>
> Could you run your cyclictest much longer?
>
> And hackbench takes ages, already without running cyclictest:

Did your read http://lkml.org/lkml/2007/12/7/181 ? Don't know if it is 
relevant here.

Juergen
-- 
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