From: Ralf Baechle <ralf@linux-mips.org>
To: Dominic Sweetman <dom@algor.co.uk>
Cc: Thiemo Seufer <ica2_ts@csv.ica.uni-stuttgart.de>,
"Maciej W. Rozycki" <macro@ds2.pg.gda.pl>,
Carsten Langgaard <carstenl@mips.com>,
"Kevin D. Kissell" <kevink@mips.com>,
linux-mips@linux-mips.org
Subject: Re: Latest sources from CVS.
Date: Sat, 7 Dec 2002 00:17:31 +0100 [thread overview]
Message-ID: <20021207001731.D12968@linux-mips.org> (raw)
In-Reply-To: <15856.59886.661994.493446@gladsmuir.algor.co.uk>; from dom@algor.co.uk on Fri, Dec 06, 2002 at 06:18:22PM +0000
On Fri, Dec 06, 2002 at 06:18:22PM +0000, Dominic Sweetman wrote:
> > The first kernel was built as 64-bit ELF using 64-bit pointer and everything
> > 64-bit. The second kernel was built using the -Wa,-32 trick. That's over
> > 12% of bloat for full 64-bitiness which brings zero gain.
>
> Percentages are dangerous things. This is 220Kbytes of memory, which
> currently represents an investment of about $0.05. There may be
> embedded linux applications which care about 5c cost, but they
> probably won't use any variety of 64 bits...
I'd worry less if that was just 220kB of unused memory wasted. But it's
actually inflated code, it's wasted i-cache and cycles. 220kB translates
to alost 7 times the size of today's typical 32kB i-cache.
Even if Thiemo was right this trick is probably the biggest micro-
optimization of the decade ...
Ralf
next prev parent reply other threads:[~2002-12-06 23:19 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-12-04 8:34 Latest sources from CVS Carsten Langgaard
2002-12-04 9:09 ` Kevin D. Kissell
2002-12-04 9:09 ` Kevin D. Kissell
2002-12-04 13:04 ` Ralf Baechle
2002-12-05 3:34 ` Ralf Baechle
2002-12-05 11:14 ` Carsten Langgaard
2002-12-05 13:47 ` Maciej W. Rozycki
2002-12-05 14:12 ` Carsten Langgaard
2002-12-05 14:27 ` Ralf Baechle
2002-12-06 12:52 ` Carsten Langgaard
2002-12-06 13:07 ` Ralf Baechle
2002-12-06 13:24 ` Carsten Langgaard
2002-12-06 13:24 ` Thiemo Seufer
2002-12-06 13:34 ` Thiemo Seufer
2002-12-06 13:41 ` Carsten Langgaard
2002-12-06 13:51 ` Thiemo Seufer
2002-12-06 16:32 ` Maciej W. Rozycki
2002-12-06 16:45 ` Thiemo Seufer
2002-12-06 17:01 ` Maciej W. Rozycki
2002-12-06 17:24 ` Thiemo Seufer
2002-12-06 18:04 ` Ralf Baechle
2002-12-06 18:30 ` Maciej W. Rozycki
2002-12-06 18:41 ` Thiemo Seufer
2002-12-06 18:58 ` Maciej W. Rozycki
2002-12-06 17:02 ` Ralf Baechle
2002-12-06 17:15 ` Thiemo Seufer
2002-12-06 17:34 ` Greg Lindahl
2002-12-06 18:18 ` Dominic Sweetman
2002-12-06 18:40 ` Greg Lindahl
2002-12-06 23:17 ` Ralf Baechle [this message]
2002-12-06 23:33 ` Thiemo Seufer
2002-12-07 0:00 ` Ralf Baechle
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