tech-userlevel archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Re: make: should -j affect cwd?

In article <>,
Steven Bellovin  <> wrote:
>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.

It is important on slower boxes, but you are right: compilation times are
dominant, specially as the version of gcc increases.


Home | Main Index | Thread Index | Old Index