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Re: Speeding up ggc-simple on stage1
- To: law at cygnus dot com
- Subject: Re: Speeding up ggc-simple on stage1
- From: Alexandre Oliva <oliva at lsd dot ic dot unicamp dot br>
- Date: 14 Jan 2000 09:09:50 -0200
- Cc: gcc-patches at gcc dot gnu dot org
- References: <4719.947847000@upchuck>
On Jan 14, 2000, Jeffrey A Law <law@cygnus.com> wrote:
>> Unfortunately, I've got a
>> slow powerpc running AIX 4.1 (it won't run GNU/Linux :-(, that takes
>> ages to build stage2 and, it seems that, whenever I attach gdb to cc1,
>> it's within running garbage collection code :-(
> Presumably that host can't use gcc-page?
Yep. configure claims the platform doesn't support mmap nor valloc :-(
> Yes, ggc-simple is painfully slow. It took several days to
> bootstrap an m68k box I've got access to using gcc-simple.
Well, the unoptimized stage1 cc1 has been trying to build tree.c for
the past 24 hours or so :-(
Nevertheless, `ps' says it's used just 54 minutes of CPU. So it looks
like the system is thrashing, which is not that surprising, given that
it's got just 16MB of memory :-( :-(
>> I believe reducing stack usage for garbage collection could help it
>> some, so I've tried to rewrite some (all?) of the recursive functions
>> in ggc-simple to try to avoid recursion as much as possible. I can't
>> say that know it's fast, but it seems to have improved a bit.
> I'd like to know that we're actually going to improve things before we
> start making changes.
Sounds reasonable.
>> Is this ok to install?
> Not without at least knowing it's an improvement. I'm not talking about
> a massive study of its performance. Build cc1 with and without this
> change and run a substantial file through the compiler.
Should it be an optimized or unoptimized cc1? Can it be cc1 from
stage1, built with gcc 2.95.2?
> combine.i, reload.i or reload1.i are always good candidates for this
> kind of test.
Ok. I hope I can obtain some results before the end of Y2K :-) :-)
> You also have some formatting problems.
Oops, sorry, thanks for pointing it out (again :-(.
It's really hard to get rid of old habits :-)
--
Alexandre Oliva http://www.ic.unicamp.br/~oliva IC-Unicamp, Bra[sz]il
oliva@{lsd.ic.unicamp.br,guarana.{org,com}} aoliva@{acm,computer}.org
oliva@{gnu.org,kaffe.org,{egcs,sourceware}.cygnus.com,samba.org}
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