On Mon, Oct 07, 2013 at 09:19:38PM +0200, Erik Cederstrand wrote: > ... > > In examining the CPU utilization graphs, the CPU generally looks > > about 5% busy for the first 15 minutes; this would be bmake determining > > dependency graphs, I expect. > > Is that one process using 100% of one core, or many processes using 5% total?
It's closer to the first, but "which core" varies a bit over time. (In one specific instance, core 17, then 13 are at near 100% within that first 15-minute interval.) > > Based on earlier work I did, where I was able to do a similar build in a > > native FreeBSD/i386 (no PAE) enviroment on the same hardware (but when > > it still only had 6GB RAM), and I managed to get the build done in 2:47, > > I believe that getting more work done in parallel in this 2:00 period is > > a key to improving performance: the 2:47 result showed that period to be > > a very busy one for the CPU. > > You need to know where your bottlenecks are during the build. Indeed. :-} > Since you have lots of RAM, you could try to rule out differences in > filesystem access by placing your jail on an mfs and building your software > off that. That's an experiment that I've been advocating, but 96GB isn't enough. > If that improves build times, then you're IO bound at least some of the time. > You should be logging disk access along with CPU and memory during the build. FWIW, I'm seeing very little CPU time spent in interrupt mode. I'll see if I can find a reasonable way to munge the output of iostat to be usable for the purpose, I suppose; thanks. Peace, david -- David H. Wolfskill da...@catwhisker.org Taliban: Evil cowards with guns afraid of truth from a 14-year old girl. See http://www.catwhisker.org/~david/publickey.gpg for my public key.
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