Re: make: should -j affect cwd?

[Steven Bellovin <smb%cs.columbia.edu@localhost>]

On Jan 18, 2012, at 12:10 12PM, Christos Zoulas wrote:
> 
> One of the problems with the current make is performance. Doing a simple
> ktrace , then kdump | grep NAMI reveals that each path is stat'ed four times
> one of them completely redundant, since it was just stat'ed before. There
> has been a lot of sandbagging in the path resolution code, to fix bugs by
> adding extra checks without understanding the original source of the problem.
> 
> The second main issue is variable evaluation, and the recent abuse of
> ${VAR:Uconstantstring}. Running a profiled make in libc reveals that 20%
> of the run is spent in tolower() and ApplyModifiers(). 50% of the run
> is spent doing stat().


Without disputing any of your factual statements, is this really important?
Make gets a workout when it's being used to build large projects, but in
such cases I suspect -- but haven't measured! -- that compilation time
strongly dominates total runtime.

                --Steve Bellovin, https://www.cs.columbia.edu/~smb