[Radiance-general] Fun with multiple cores and rtrace

[Greg Ward]

Hi Randolph,

What is unexpected about this process status?  You asked for -n 8, so you get 8 active processes and one that collects the results.  They are all duplicates of each other.  What are the exact circumstances of the slowdown?  What options are hidden in your sensparm.opt file?

-Greg

> From: "Randolph M. Fritz" <rfritz at lbl.gov>
> Date: February 2, 2011 9:29:55 PM PST
> 
> I finally managed to get Linux going on my modelling system, an eight-core
> ThinkStation.  It was running Radiance very fast.  Then I started seeing ps
> output like this:
> 
> 6589 ?        S      0:00 rtrace -n 8 -h -I @sensparm.opt ot-3.oct
> 6592 ?        R     29:32 rtrace -n 8 -h -I @sensparm.opt ot-3.oct
> 6593 ?        R     29:32 rtrace -n 8 -h -I @sensparm.opt ot-3.oct
> 6594 ?        R     29:32 rtrace -n 8 -h -I @sensparm.opt ot-3.oct
> 6595 ?        R     29:32 rtrace -n 8 -h -I @sensparm.opt ot-3.oct
> 6596 ?        R     29:32 rtrace -n 8 -h -I @sensparm.opt ot-3.oct
> 6597 ?        R     29:32 rtrace -n 8 -h -I @sensparm.opt ot-3.oct
> 6598 ?        S     41:03 rtrace -n 8 -h -I @sensparm.opt ot-3.oct
> 6599 ?        S     49:48 rtrace -n 8 -h -I @sensparm.opt ot-3.oct
> 
> And it slowed down by a factor of three. My impression is that there has been an
> OS glitch and it is in fact only using one core.  Anyone else seen this?
> 
> Head Debian build of Radiance, Ubuntu 10.10, most current version.
> 
> Randolph