On Nov 28, 2011 11:32 AM, "Michael Mol" <mike...@gmail.com> wrote: >
----- >8 snip > > MAKEOPTS would be -j16, -l10. (Which actually goes up to about 12 or > 13 based on that N*1.6 behavior) > ----- >8 snip Just in case anyone wonders where the multiplier "1.6" comes from: There had been a discussion somewhere (I forgot where exactly, sorry) about load numbers. The final conclusion was that the ideal load number for today's processors is 2*N, because with the out-of-order capability of modern processors, two instructions can overlap in the pipeline, even without hyperthreading. Unfortunately, striving for 2*N will inadvertently result in short bursts of > 2*N, and this potentially induce a stall, which will be very costly. 1.8*N gives a 10% margin for burst activities, while 1.6*N gives a 20% margin. Since emerging packages has a sudden increase in load when autoconfigure finishes and make fires up all the parallel building, I figure 20% margin will be better. Of course, that's before @mikemol made me aware of MAKEOPTS -l, so I am now tempted to raise the load-average to 1.8*N, letting make handle the bursts. Rgds,
