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Re: Stability Under Load


On Friday 19 August 2011 16:10:43 Gordan Bobic wrote:
>  On Fri, 19 Aug 2011 15:55:57 +0200, Marc Dietrich <marvin24@xxxxxx> wrote:
> > Am Freitag 19 August 2011, 11:18:31 schrieb Gordan Bobic:
> >>  As some of you may have already heard on the IRC channel, I had my
> >>  AC100 suddenly become very unstable under load. When doing big
> >> compile
> >> [...]
> >>  My gut feeling at the moment is that the RAM could be over-timed so
> >>  I'm going to try modifying the kernel code to relax the RAM timings by
> >>  a notch.
> > 
> > we are not touching RAM timings so far on kernel 2.6.38. It may be
> > possible that the original kernels does so.
>  Well, my plan was to up the timings in
>  arch/arm/mach-tegra/board-paz00-memory.c. Can you confirm whether the
>  values there are in units of clock cycles? Or is it ns? Also which line
>  corresponds to CAS? I can see RAS, RC, RCD, RRD, RFC, but can't see a
>  value for CAS, which is, at least in theory, the most imporant one.

AFAIK, they are in cycles, but as I said, these values are not used now (see the 
ifdef 0 at the end of the file). The reason is that I don't have the values for 
166 MHz on Micron and the Hynix tables caused instabilities. So they are just 
there as a "reminder". But of course, you can remove the ifdef and try yourself. 
> > [...] 
> > It could also be related to power supply. What we do is modifing the
> > voltage
> > supplies for serveral power sources. I had the feeling, that Toshiba
> > undervoltaged some CPU supplies in order to save energy (compared to
> > other
> > boards). So I increased SM1 from 1V to 1.2V which may have been
> > wrong.
>  How did you do this?

check board-paz00-power.c

> > It would be nice if you could test a .32 based kernel and see if it
> > also happens there. Also you could try your new model.
>  I haven't tried 2.6.32 because I couldn't find one at the time, but I
>  tried the old 2.6.29 and 2.6.38, and the instability on my old AC100 was
>  the same. Haven't tried it on the new one yet. Do you think 2.6.32 could
>  be behaving differently to both of those? If so, why? Where can I get
>  the Tegra-patched 2.6.32 kernel?

gitorious.org/ac100? (on the front page)


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