Re: gcc build / test times on multi-core hosts?

[Andrew Haley <aph at redhat dot com>]

Laurent GUERBY writes:
 > On Fri, 2006-02-17 at 22:43 +0000, Joern RENNECKE wrote:
 > > Has anybody done timings for gcc bootstrap / cross builds and regtests 
 > > with modern multi-core processors?  I wonder what a sensible modern 
 > > configuration would be for gcc development, but the the multimedia and 
 > > games benchmarks I found on the web neither seem particularily relevant, 
 > > nor do they paint a uniform picture.
 > 
 > On a  "AMD Athlon(tm) 64 X2 Dual Core Processor 3800+" (2.0 GHz), 2GB of
 > RAM trunk configured with:
 > 
 > --enable-languages=c,ada,c++,fortran,java,treelang,objc 
 > --enable-__cxa_atexit
 > --disable-nls 
 > --enable-threads=posix 
 > --disable-multilib 
 > --enable-checking
 > 
 > Gives the following timing at -j1:
 > 
 > === GCCBOOT start     === 2006-02-16 22:13:46
 > === GCCBOOT configure === 2006-02-16 22:13:46
 > === GCCBOOT bootstrap === 2006-02-16 22:13:51
 > === GCCBOOT doc       === 2006-02-17 01:48:53
 > === GCCBOOT check     === 2006-02-17 01:48:53
 > === GCCBOOT summary   === 2006-02-17 04:15:25
 > === GCCBOOT install   === 2006-02-17 04:15:37
 > === GCCBOOT done      === 2006-02-17 04:20:03
 > 
 > So that's 6h07 total, bootstrap 3h35 and check 2h27. I assume
 > -j2 could cut bootstrap times by about two, I'm not
 > sure check is parallel (Ada check isn't for sure).
 > 
 > On a Pentium III 1GHz, bootstrap is 5h55 and check 5h30
 > (on an older version of the tree), so p3/amd64
 > 
 > Removing Ada from --enable-languages will also help :).

As a comparison point, I get

real    73m39.275s
user    113m19.549s
sys     15m26.010s

for the bootstrap: that's 1h14 elapsed time.  That's on a "AMD
Athlon(tm) 64 X2 Dual Core Processor 4800+" (2.4 GHz) with make -j3.
That's 129min of CPU time in 74min of elapsed time, a pretty good
processor utilization ratio of 1.75 : 2.

Andrew.