From: <cutaway@bellsouth.net>
To: "Maciej W. Rozycki" <macro@linux-mips.org>
Cc: <linux-kernel@vger.kernel.org>
Subject: Re: .../asm-i386/bitops.h performance improvements
Date: Wed, 15 Jun 2005 19:48:29 -0400 [thread overview]
Message-ID: <000101c57207$6b4f3de0$2800000a@pc365dualp2> (raw)
In-Reply-To: Pine.LNX.4.61L.0506151632280.13835@blysk.ds.pg.gda.pl
The only thing I've seen so far that loses is a straight original 486. Its
pipe is somewhat more simple minded and interlock prone than later models.
PPro, K6 and 386SX are big winners.
On the 386's, lacking actual pipeline, the compactness of the LEA over the
SHL/ADD can be more of an overriding factor.
----- Original Message -----
From: "Maciej W. Rozycki" <macro@linux-mips.org>
To: <cutaway@bellsouth.net>
Cc: <linux-kernel@vger.kernel.org>
Sent: Wednesday, June 15, 2005 11:34
Subject: Re: .../asm-i386/bitops.h performance improvements
>
> Be careful about model-specific penalties from using certain address
> modes and AGIs when using "lea" for such calculations.
>
> Maciej
next prev parent reply other threads:[~2005-06-15 23:17 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-06-15 8:53 .../asm-i386/bitops.h performance improvements cutaway
2005-06-15 12:18 ` Gene Heskett
2005-06-15 13:06 ` Richard B. Johnson
2005-06-15 19:18 ` cutaway
2005-06-15 15:34 ` Maciej W. Rozycki
2005-06-15 23:48 ` cutaway [this message]
[not found] <4fB8l-73q-9@gated-at.bofh.it>
[not found] ` <4fF2j-1Lo-19@gated-at.bofh.it>
2005-06-15 14:57 ` Bodo Eggert
2005-06-15 15:30 ` Maciej W. Rozycki
2005-06-15 16:06 ` Richard B. Johnson
2005-06-15 16:29 ` Maciej W. Rozycki
2005-06-15 19:10 ` Bodo Eggert
2005-06-16 3:26 ` Stephen Rothwell
2005-06-16 7:10 ` Mikael Pettersson
2005-06-15 23:53 ` cutaway
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