From: Zack Weinberg <zack@codesourcery.com>
To: Roger Sayle <roger@eyesopen.com>
Cc: gcc@gcc.gnu.org, gcc-patches@gcc.gnu.org,
Diego Novillo <dnovillo@redhat.com>
Subject: Re: Bootstrap times on mainline are getting worse
Date: Sat, 19 Oct 2002 17:26:00 -0000 [thread overview]
Message-ID: <20021019181056.GG24290@codesourcery.com> (raw)
In-Reply-To: <Pine.LNX.4.33.0210191115440.8664-100000@www.eyesopen.com>
On Sat, Oct 19, 2002 at 11:25:55AM -0600, Roger Sayle wrote:
>
> Hi Zack,
>
> > > A 'time make bootstrap' on version "2002-10-03" gives:
> > >
> > > real 57m38.632s
> > > user 51m20.200s
> > > sys 4m55.500s
> > >
> > > With this patch I get:
> > >
> > > real 58m16.766s
> > > user 51m14.720s
> > > sys 5m0.850s
> >
> > I smell cache blowout. Notice how the real and system times went up,
> > but the user time went down?
>
> I think that you're barking up the wrong tree on this one. As I've
> mentioned in http://gcc.gnu.org/ml/gcc/2002-10/msg01183.html, we're
> still looking for a 6% (approx 4 minute slow-down) around October 5th.
Yeah, I wrote this before I saw your message.
I still think it's worth shrinking processor_costs - we're getting
nickled and dimed to death on cache utilization, and this is a cheap
way to get quite a bit of space back.
> Also be carefull about changing these RTX costs to unsigned char.
> Pentium4 already has integer division costs at around 120, and
> improvements in superscalar issue vs memory latency could easily
> push values above 256 on x86 within only a year or so. Just look
> at the curves for i386, i486, pentium, pentiumpro, pentium4....
The only thing that's really gone up is the integer divide cost. Even
load/store costs are stable in the 2-16 cycles range (presumably this
is cost to fetch from L1 cache). I'd wait until we really do have a
cost above 256 and then change just that one entry to unsigned short.
zw
next prev parent reply other threads:[~2002-10-19 18:11 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-19 14:51 Roger Sayle
2002-10-19 17:26 ` Zack Weinberg [this message]
2002-10-20 1:23 ` Roger Sayle
2002-10-20 15:09 ` Zack Weinberg
2002-10-19 18:36 ` Geert Bosch
2002-10-20 5:46 ` Tim Prince
-- strict thread matches above, loose matches on Subject: below --
2002-10-19 13:51 Roger Sayle
2002-10-17 17:10 Robert Dewar
2002-10-17 17:26 ` Diego Novillo
2002-10-17 12:51 Diego Novillo
2002-10-17 13:02 ` Andreas Schwab
2002-10-18 4:34 ` Michael Ritzert
2002-10-18 4:52 ` Kaveh R. Ghazi
2002-10-18 5:42 ` Diego Novillo
2002-10-18 9:02 ` Kaveh R. Ghazi
2002-10-18 9:48 ` Diego Novillo
2002-10-18 12:34 ` David Edelsohn
2002-10-19 12:01 ` Pop Sébastian
2002-10-19 14:14 ` Zack Weinberg
2002-10-20 9:19 ` Pop Sébastian
2002-10-20 14:41 ` Pop Sébastian
2002-10-20 15:41 ` Pop Sébastian
2002-11-04 17:54 ` Pop Sébastian
2002-10-17 14:22 ` Neil Booth
2002-10-17 14:49 ` Diego Novillo
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