speeding up buildworld/kernel

[Erik Trulsson]

On Thu, Jan 24, 2008 at 03:32:18PM -0500, Maxim Khitrov wrote:
> On Jan 24, 2008 3:15 PM, Aryeh M. Friedman <aryeh.friedman at gmail.com> wrote:
> > I update my sources at least once a day and do buildworld/kernel just
> > as often... It seems some stuff that needs not be recompiled is on
> > every single run for example gcc and kerbos.   I have NO_CLEAN in
> > /etc/make.conf is there anything else I can do to speed stuff up...
> > for ref here is my /etc/make.conf:
> >
> > CPUTYPE?=nocona
> > KERNCONF=MONSTER
> > NO_CLEAN=
> > NO_LPR=
> > # added by use.perl 2008-01-17 11:48:48
> > PERL_VER=5.8.8
> > PERL_VERSION=5.8.8
> >
> > - --
> > Aryeh M. Friedman
> > FloSoft Systems, Java Tool Developers
> > Developer, not business, friendly
> > http://www.flosoft-systems.com
> 
> I might be wrong, but NO_CLEAN seems like a bad idea except in special
> circumstances. Install ccache, but make sure you set
> CCACHE_HASH_COMPILER environment variable to 1. That will make sure
> that the cache stays valid if the compiler executable is overwritten
> by an identical copy (as it would be on installworld). When the
> compiler changes the cache will be repopulated on the next rebuild.

You are indeed wrong.  NO_CLEAN will work fine almost all the time - except
in special circumstances.  The few times it does not work one can always do
a 'make clean' by hand first. (Or even faster: 'rm -fr /usr/obj/*')
If you set WRKDIRPREFIX to some useful value you can do the same thing
for the ports tree.
Personally I always compile with -DNO_CLEAN and use 'rm -fr' to clean.
I have never had problems originating with this.

ccache is not very useful for buildworld, since among the first thing
buildworld does is to build the compiler and then use the newly built
compiler to compile the rest. I.e. the already installed compiler (which is
the one ccache will handle) will not be used for most of the build thus
removing almost all the advantage of ccache.
It is supposed to be possible to use ccache for buildworld as well, but
that would require a bit of hackery.


As for speeding up the build even more there a couple of things that can be
tried:

  You can add NO_PROFILE=true to make.conf if you do not need profiling
  libraries.
  
  Set CFLAGS/COPTFLAGS to -O instead of -O2. This should speed up the
  compiler a bit since it will no have to do as much work.  This will make
  programs slightly less well optimized, but since the vast majority of the
  system binaries are not really CPU-bound anyway it is unlikely that any
  performance loss will be noticed.

  If you have more than one CPU-core in your machine (and an SMP-enabled
  kernel) you can use the -j flag to tell make to run several jobs in
  parallell.  Just be aware that building with -j does get broken
  occasionaly and there is no promise that it will always be fixed quickly. 
  If you do run into problems when building with -j, try without -j before
  sending any bug reports.





-- 
<Insert your favourite quote here.>
Erik Trulsson
ertr1013 at student.uu.se