← Back to team overview

ac100 team mailing list archive

Re: Stability Under Load


On 08/20/2011 05:47 PM, Gordan Bobic wrote:
Which kernel are you using?

A somewhat older build of Marc's kernel (one month), the one
I have in my Debian repository + the change to use 1000 instead
of 1200.

I presume you mean 1200mV rather than 1200MHz. If it's 1200MHz, I'd
like to know where to tweak that. ;)

I never said anything of Hz. It's all mV (if it's mV, what are 1.2V
used for? The voltage from the battery/charger is clearly 10-12V).

Well, my testing has been going on for 6+ hours. Considering I
couldn't get an hour without errors before (and sometimes
several/hour, and that's just the detected ones), I'd say it's a
very definitive improvement. So much so that I'm vaguely tempted to
try reducing it to 950mV. ;)

Given that the minimum it currently scales to would be 725, 950
is certainly save.

Seems there are limits in hardware. I built a kernel with the upper
bound set to 900, and now I get a lot of this in the logs, while the CPU
is stuck at 216MHz:

Failed to set dvfs regulator vdd_cpu
Failed to set regulator vdd_cpu for clock cpu to 875mV

This should have read 975mV

cpu-tegra: Failed to set cpu frequency to 1000000kHz

over, and over and over.

Seems 975mV may be the lower limit, going to try that next.

I can confirm that 975mV works without throwing any errors and the CPU
does get up to 1GHz. Going to leave it load testing for a few hours and
see if it's stable.

And, unfortunately, it isn't stable. It seems that going from 1000mV down to 975mV makes a big difference to stability (multiple errors in the past hour, even worse than at 1200mV).

I still saw one error at 1000mV on my old AC100, but that could have been something else (it is plausible I knocked the USB stick, since there were no errors in the previous 6 hours), so I'm going to re-test and if I can find an error I'll try 1025mV overnight.


Follow ups