[systemd-devel] [PATCH] use dolt.m4 to speedup compilation

[josh at joshtriplett.org]

On Thu, Mar 05, 2015 at 10:33:19PM -0300, Lucas De Marchi wrote:
> On Thu, Mar 5, 2015 at 9:58 PM,  <josh at joshtriplett.org> wrote:
> > On Fri, Mar 06, 2015 at 12:55:38AM +0100, Michael Biebl wrote:
> >> 2015-03-05 11:58 GMT+01:00  <harald at redhat.com>:
> >> > From: Harald Hoyer <harald at redhat.com>
> >> >
> >> > The speedup is significant
> >> >
> >> > Original libtool
> >> > $ ccache -C && make clean && time make -j4
> >> > […]
> >> > real    6m4.104s
> >> > user    13m49.234s
> >> > sys    7m37.864s
> >> >
> >> > Original libtool + dolt
> >> > $ ccache -C && make clean && time make -j4
> >> > […]
> >> > real    2m24.869s
> >> > user    7m30.198s
> >> > sys    1m17.813s
> >>
> >> Hm, the speedup is nowhere near as significant here:
> >> without dolt (make):
> >> real 4m2.749s
> >> user 3m9.304s
> >> sys 0m19.032s
> >>
> >> with dolt (make):
> >> real 3m33.756s
> >> user 2m59.476s
> >> sys 0m17.632s
> >>
> >> without dolt (make -j6):
> >> real 1m42.001s
> >> user 5m3.680s
> >> sys 0m26.608s
> >>
> >> with dolt (make -j6)
> >> real 1m35.267s
> >> user 4m50.956s
> >> sys 0m24.724s
> >>
> >>
> >> libtool version is 2.4.2.
> >
> > That's more what I'd expect with current versions of libtool, which has
> > supposedly fixed many of the issues that motivated the creation of dolt
> > in the first place.
> 
> Maybe it was a regression in libtool from 2.4.2 <-> 2.4.5?  I have 2.4.5 here:
> 
> make -j6, libtool
> real    4m53.924s
> user    11m4.323s
> sys     0m54.880s
> 
> make -j6, dolt
> real    1m58.653s
> user    6m20.523s
> sys     0m28.920s

Interesting.  How easily can you try 2.4.2?

- Josh Triplett