Question: is this using -j4 MAKE="make -j4" so that it will spawn 4
proccesses for every subdir? I have found that doing this yeilds about
60 compile proccesses on average during the build.
On Thu, 1 Jun 2000, Rajagopal Ananthanarayanan wrote:
> Going to -j4, elapsed time went from 808sec -> 254sec (4:14)
> which is a scaling of ~3.2 times ... if -j4 had had an
> elapsed time of 202sec (3:22) then it would have been perfect
> scaling. But add in the fact that -j4 vs. NO-J would introduce
> additional complexity in the make itself, which now spawns
> more processes, etc. ... this shows in the increased system time
> for -j4; of course the extra system time also counts increased
> lock contention. For this particular workload (primarily user-mode,
> little-or-no-shared parallelism), -j4 did pretty good.
> Finally, -j6 & -j8 may not discover any extra parallelism
> in the makes ... one gross way to check this is to watch "top"
> and see how many "cc" processes are running on an average.
> If it stays at 4, then -j4 is all that'll work.