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Re: [C++/Obj-C++ PATCH] Fix Objective-C++ breakage


On Fri, Mar 28, 2008 at 7:04 AM, Paolo Bonzini <bonzini@gnu.org> wrote:
>
>  > The baseline bootstrap --enable-languages=all and "make check" took
>  > 3:40:59.  The patched bootstrap enabling objc++ by default took 3:41:41,
>  > so that's only *42 seconds* longer, or 0.3% more.
>
>  When I'll remove target libiberty, I hope to save more than that.
>  Throwing another piece of data in the thread. :-)

:)

So I thought I make some measurements myself.  For "bad" patches
I do all-languages and multilib bootstrap and tests on x86_64-linux.
Bootstrap takes

11566.82user 835.02system 37:41.31elapsed 548%CPU

and multilib testing (RUNTESTFLAGS="--target_board=unix/\{,-m32\}")

10793.09user 3616.46system 59:11.61elapsed 405%CPU

on a moderately old 8 core machine (with enough memory to allow
-j10 bootstrap and -j8 test).  As you can see we can not even fully
utilize all the CPUs (the big generator files are likely a problem and
bad parallelism in the libjava build is another), testing time is also
hugely dominated by all the forks() (see that system time number!).

Still this means my regular bootstrap and testing time is around
one hour (minus ada and minus the -m32 testing), which IMHO is
very reasonable.  If you double that it would be the time it takes
on a single-CPU quad-core machine which I expect a free-time
volunteer GCC developer to have access to ;)

If we can improve on the bootlenecks (dejagnu anyone?  splitting
insn-* and gen*, or building the generator files optimized during
stage1?) it would maybe scale even better, which even I would
appreciate.

Thanks,
Richard.


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