On Fri, 30 Sep 2011 11:15:16 -0700, Mark Knecht wrote: > > If your MAKEOPTS is -j3 then it's not going to use more than 3 cores > > at a time but it will touch all 12 cores throughout the process > > because of the normal load balancing. If you want it to use only 3 > > specific cores, you would need to set the processor affinity (usually > > done using the "taskset" command from sys-apps/util-linux).
> My experience with -j3 is not that it limits emerge to 3 CPU cores but > rather it limits emerge to running 3 _jobs_. There's a big difference. > 1 job can use 12 cores if gcc spawns a lot of stuff in parallel, which > in my experience it does. It's this parallel spawn running up to 12 > cores in use which causes the machine to lag. Even when not setting > the -j option at all which results in a single package being emerged > at one time, I often use 6-12 cores in use for short periods of time > as gcc builds that package. That's the --jobs option for emerge. The suggestion was to set the -J option in MAKEOPTS, which tells GCC how many compilation threads to run at once, and that's one core per thread. You'll also need to set -j 1 for emerge, which will also reduce the amount of disk thrashing that can happen when two package hit unpack at the same time. -- Neil Bothwick If at first you don't succeed, skydiving is not for you.
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