On Sun, Oct 15, 2017 at 8:51 PM, Walter Dnes <waltd...@waltdnes.org> wrote:
> On Sat, Oct 14, 2017 at 06:25:35AM -0500, Dale wrote
>
>> Some of my make.conf entries. You may not need all of these so edit out
>> what you don't want or change values if you need to. I have a four core
>> CPU.
>>
>> FEATURES="-usersync -userpriv -usersandbox buildpkg sandbox parallel-fetch"
>>
>> MAKEOPTS="-j5"
>
> There is some controversy over setting MAKEOPTS=${number of threads}
> possibly being better than MAKEOPTS=${number of threads} + 1
> https://blogs.gentoo.org/ago/2013/01/14/makeopts-jcore-1-is-not-the-best-optimization/
>
I received the same results when I tested it myself. On modern servers
especially, RAM access speed seems to be matched to core processing
capability very well.
Strangely, adding to the build thread count doesn't seem to help when
disk IO is the bottleneck. It is conceivable that it could but in
practice the location of build data and files seems to be disperse
enough that there are no great access optimizations, and each read
blocks individually.
Cheers,
R0b0t1
