On Thu, Jan 27, 2011 at 03:12:49PM +0100, J. Roeleveld wrote: > On Thursday 27 January 2011 15:05:25 YoYo Siska wrote: > > On Thu, Jan 27, 2011 at 03:33:21PM +0200, Nikos Chantziaras wrote: > > > On 01/27/2011 03:11 PM, Dale wrote: > > > >[...] > > > >I am using the -j option for the first time now. I'm updating KDE. It > > > >seems to work fine. It doesn't scroll all the stuff like with a regular > > > >emerges but this new rig is so fast, I can't read it anyway. I did have > > > >a package to fail and it spit out the error for me to read. > > > > > > You don't need that if you have MAKEOPTS set in your make.conf, > > > which is preferred. The -j option of emerge emerges multiple > > > packages, while with MAKEOPTS set to "-j4" or whatever does a > > > parallel build in the same package (meaning compiling multiple > > > source files at the same time). > > > > > > It's preferred because with "emerge -jN" the last package will only > > > use one CPU, while with "-jN" in MAKEOPTS even the last package will > > > use N CPUs. Furthermore, emerge can't always build N packages at > > > the same time because one can depend on the other, so it will have > > > to wait until the dependency is built. > > > > On the other hand, unpacking, configure and install stages are not > > parallel and emerge can do those in parallel for different packages... > > The best would be somewhere in the middle ;) > > > > > > There are also the load-average options to -j, i.e.: > > MAKEOPTS="-j -l5" emerge -j --load-average=5 .... > > > > which makes make spawn parallel processes while load average is below 5 > > and the same for emerge spawning parallel ebuilds (when make isn't > > parallel enough) > > > > yoyo > > Hmmm... didn't know about that one yet. > Does that mean that by doing it like that, the emerge-process (and compile- > processes) will try to keep the load average at 5 and if that is lower, it > will keep adding more processes? >
Yes. It might not be perfect, but mostly it works pretty well. Once make started 10 or so process, which ate all my ram, because I forgot to reenable swap, when I was playing with something before that :) yoyo
