From: Jeff Garzik <jeff@garzik.org>
To: Grzegorz Kulewski <kangur@polcom.net>
Cc: Alan <alan@lxorguk.ukuu.org.uk>,
Mikael Pettersson <mikpe@it.uu.se>,
s0348365@sms.ed.ac.uk, torvalds@osdl.org,
76306.1226@compuserve.com, akpm@osdl.org, bunk@stusta.de,
greg@kroah.com, linux-kernel@vger.kernel.org,
yanmin_zhang@linux.intel.com
Subject: Re: kernel + gcc 4.1 = several problems
Date: Wed, 03 Jan 2007 06:51:37 -0500 [thread overview]
Message-ID: <459B98C9.1040309@garzik.org> (raw)
In-Reply-To: <Pine.LNX.4.63.0701031128420.14187@alpha.polcom.net>
Grzegorz Kulewski wrote:
> On Wed, 3 Jan 2007, Alan wrote:
>> The proper fix for all of this mess is to fix the gcc compiler suite to
>> actually generate i686 code when told to use i686. CMOV is an optional
>> i686 extension which gcc uses without checking. In early PIV days it made
>> sense but on modern processors CMOV is so pointless the bug should be
>> fixed. At that point an i686 kernel would contain i686 instructions and
>> actually run on all i686 processors ending all the i586 pain for most
>> users and distributions.
>
> Could you explain why CMOV is pointless now? Are there any benchmarks
> proving that?
In theory modern processors should have no trouble converting a
test/move sequence into the same uops generated by a cmov instruction,
for one.
Jeff
next prev parent reply other threads:[~2007-01-03 11:52 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-03 2:12 kernel + gcc 4.1 = several problems Mikael Pettersson
2007-01-03 2:20 ` Alistair John Strachan
2007-01-05 15:53 ` Alistair John Strachan
2007-01-05 16:02 ` Linus Torvalds
2007-01-05 16:19 ` Alistair John Strachan
2007-01-05 16:49 ` Linus Torvalds
2007-01-07 0:36 ` Pavel Machek
2007-01-07 0:57 ` Alistair John Strachan
2007-01-03 5:55 ` Willy Tarreau
2007-01-03 10:29 ` Alan
2007-01-03 10:32 ` Grzegorz Kulewski
2007-01-03 11:51 ` Jeff Garzik [this message]
2007-01-03 12:44 ` Alan
2007-01-03 13:32 ` Arjan van de Ven
2007-01-03 13:58 ` Jakub Jelinek
2007-01-03 14:28 ` Alan
2007-01-03 16:06 ` Linus Torvalds
2007-01-03 16:03 ` Linus Torvalds
2007-01-03 17:01 ` l.genoni
2007-01-03 17:45 ` Tim Schmielau
2007-01-03 20:24 ` Linus Torvalds
2007-01-03 17:06 ` l.genoni
2007-01-03 17:53 ` Mariusz Kozlowski
2007-01-03 19:47 ` Denis Vlasenko
2007-01-03 20:38 ` Linus Torvalds
2007-01-03 21:48 ` Denis Vlasenko
2007-01-03 22:13 ` Linus Torvalds
2007-01-03 21:44 ` Thomas Sailer
2007-01-03 22:08 ` Linus Torvalds
2007-01-04 3:08 ` Zou, Nanhai
2007-01-04 15:34 ` Linus Torvalds
-- strict thread matches above, loose matches on Subject: below --
2007-01-04 7:11 Albert Cahalan
2007-01-04 16:43 ` Segher Boessenkool
2007-01-04 17:04 ` Albert Cahalan
2007-01-04 17:24 ` Segher Boessenkool
2007-01-04 17:47 ` Linus Torvalds
2007-01-04 18:53 ` Segher Boessenkool
2007-01-04 19:10 ` Al Viro
2007-01-05 17:17 ` Pavel Machek
2007-01-06 8:23 ` Segher Boessenkool
2007-01-04 17:37 ` Linus Torvalds
2007-01-04 18:34 ` Segher Boessenkool
2007-01-04 22:02 ` Geert Bosch
2007-01-07 4:25 ` Denis Vlasenko
2007-01-07 4:45 ` Linus Torvalds
2007-01-07 5:26 ` Jeff Garzik
2007-01-07 15:10 ` Segher Boessenkool
2007-01-26 22:05 ` Michael K. Edwards
2007-01-04 18:08 ` Andreas Schwab
2006-12-20 14:21 Oops in 2.6.19.1 Alistair John Strachan
2006-12-30 16:59 ` Alistair John Strachan
2006-12-31 16:27 ` Adrian Bunk
2006-12-31 16:55 ` Alistair John Strachan
2007-01-02 21:10 ` kernel + gcc 4.1 = several problems Adrian Bunk
2007-01-02 21:56 ` Alistair John Strachan
2007-01-02 22:06 ` D. Hazelton
2007-01-02 23:24 ` Adrian Bunk
2007-01-02 23:41 ` D. Hazelton
2007-01-03 2:05 ` Horst H. von Brand
2007-01-02 22:13 ` Linus Torvalds
2007-01-02 23:18 ` Alistair John Strachan
2007-01-03 1:43 ` Linus Torvalds
2007-01-02 22:01 ` Linus Torvalds
2007-01-02 23:09 ` David Rientjes
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