From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Andi Kleen <ak@suse.de>
Cc: Arjan van de Ven <arjan@infradead.org>,
linux-kernel@vger.kernel.org,
Chuck Ebbert <76306.1226@compuserve.com>,
Zachary Amsden <zach@vmware.com>,
Jan Beulich <jbeulich@novell.com>, Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH RFC 0/6] Implement per-processor data areas for i386.
Date: Sun, 27 Aug 2006 11:27:17 -0700 [thread overview]
Message-ID: <44F1E405.6090208@goop.org> (raw)
In-Reply-To: <200608272007.47741.ak@suse.de>
Andi Kleen wrote:
> On AMD K7/K8 a segment register prefix is a single cycle penalty.
>
> I couldn't find anything in the Intel optimization manuals on it, but I assume
> it's also not dramatic.
>
All I could find was:
* avoid multiple prefixes (which was the least important guideline
in instruction selection)
* avoid using multiple segment registers (the pentium M only has one
level of segment register renaming)
* avoid prefixes which take the instruction length over 7 bytes
None of these apply to the use of %gs to access PDA.
Most of the discussion about prefixes is in avoiding the 0x66 16-bit prefix.
J
next prev parent reply other threads:[~2006-08-27 18:27 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-27 8:44 [PATCH RFC 0/6] Implement per-processor data areas for i386 Jeremy Fitzhardinge
2006-08-27 8:44 ` [PATCH RFC 1/6] Basic definitions for i386-pda Jeremy Fitzhardinge
2006-08-27 8:44 ` [PATCH RFC 2/6] Initialize the per-CPU data area Jeremy Fitzhardinge
2006-08-27 8:44 ` [PATCH RFC 3/6] Use %gs as the PDA base-segment in the kernel Jeremy Fitzhardinge
2006-08-27 9:49 ` Keith Owens
2006-08-27 10:01 ` Jeremy Fitzhardinge
2006-08-27 15:57 ` Andi Kleen
2006-08-27 16:36 ` Jeremy Fitzhardinge
2006-08-27 17:20 ` Jeremy Fitzhardinge
2006-08-27 18:19 ` Andi Kleen
2006-08-27 20:03 ` Jan Engelhardt
2006-08-27 23:38 ` Jeremy Fitzhardinge
2006-08-28 9:51 ` Jan Beulich
2006-08-28 14:54 ` H. J. Lu
2006-08-28 17:24 ` H. Peter Anvin
2006-08-27 8:44 ` [PATCH RFC 4/6] Fix places where using %gs changes the usermode ABI Jeremy Fitzhardinge
2006-08-27 15:59 ` Andi Kleen
2006-08-27 16:37 ` Jeremy Fitzhardinge
2006-08-27 8:44 ` [PATCH RFC 5/6] Implement smp_processor_id() with the PDA Jeremy Fitzhardinge
2006-08-27 8:44 ` [PATCH RFC 6/6] Implement "current" " Jeremy Fitzhardinge
2006-08-27 16:01 ` Andi Kleen
2006-08-27 16:38 ` Jeremy Fitzhardinge
2006-08-27 9:47 ` [PATCH RFC 0/6] Implement per-processor data areas for i386 Arjan van de Ven
2006-08-27 16:46 ` Jeremy Fitzhardinge
2006-08-27 17:44 ` Arjan van de Ven
2006-08-27 18:07 ` Andi Kleen
2006-08-27 18:27 ` Jeremy Fitzhardinge [this message]
2006-08-27 16:01 ` Andi Kleen
2006-08-27 16:41 ` Jeremy Fitzhardinge
2006-08-27 17:21 ` Andreas Mohr
2006-08-27 17:34 ` Jeremy Fitzhardinge
2006-08-27 18:23 ` Andreas Mohr
2006-08-27 18:04 ` Andi Kleen
2006-08-27 18:27 ` Andreas Mohr
2006-08-27 18:35 ` Andi Kleen
-- strict thread matches above, loose matches on Subject: below --
2006-08-28 9:06 Chuck Ebbert
2006-08-30 9:00 Chuck Ebbert
2006-08-30 9:17 ` Jeremy Fitzhardinge
2006-08-30 12:33 Chuck Ebbert
2006-08-30 12:54 ` Andi Kleen
2006-08-30 16:39 ` Jeremy Fitzhardinge
2006-08-30 16:48 ` Andi Kleen
2006-08-30 17:13 ` Jeremy Fitzhardinge
2006-08-30 17:32 ` Andi Kleen
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