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From: Segher Boessenkool <segher@kernel.crashing.org>
To: "Zhu Ebony-r57400" <ebony.zhu@freescale.com>
Cc: linuxppc-dev@ozlabs.org, Paul Mackerras <paulus@samba.org>
Subject: Re: [patch][0/5] powerpc: Add support to fully comply with IEEE-754standard
Date: Fri, 12 Jan 2007 13:03:53 +0100	[thread overview]
Message-ID: <009dcf6d65c2d14067471cb2df09fae2@kernel.crashing.org> (raw)
In-Reply-To: <32F3CC26D4DAC44E8ECD07155727A46E816A18@zch01exm20.fsl.freescale.net>

> When floating-point underflow exceptions are disabled
> (SPEFSCR[FUNFE] is cleared) and the result of a floating-point 
> operation
> underflows, a signed zero result is produced.

You probably want to make at least this one tweakable
per-process; on some important algorithms (some FFTs
etc.) the results are perfectly acceptable with underflow-
to-zero and the performance difference is huge.  AltiVec
can do this per-process too, for example -- it has a
user register for setting this, you need some other
interface though.


Segher

  parent reply	other threads:[~2007-01-12 12:03 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-12  5:19 [patch][0/5] powerpc: Add support to fully comply with IEEE-754 standard Zhu Ebony-r57400
2007-01-12  5:29 ` Paul Mackerras
2007-01-12  5:46   ` Kumar Gala
2007-01-12  8:27     ` Zhu Ebony-r57400
2007-01-12 12:06       ` Segher Boessenkool
2007-01-15  8:41         ` Zhu Ebony-r57400
2007-01-12  6:38   ` [patch][0/5] powerpc: Add support to fully comply with IEEE-754standard Zhu Ebony-r57400
2007-01-12  6:49     ` Kumar Gala
2007-01-12 12:03     ` Segher Boessenkool [this message]
2007-01-15  8:16       ` Zhu Ebony-r57400
2007-01-15 16:08         ` Segher Boessenkool
2007-01-12  6:41 ` [patch][0/5] powerpc: Add support to fully comply with IEEE-754 standard Kumar Gala
2007-01-12  8:09   ` Zhu Ebony-r57400
2007-01-12 12:04     ` Segher Boessenkool
2007-01-15  6:45       ` Zhu Ebony-r57400
2007-01-15 15:54         ` Segher Boessenkool
2007-01-12 18:36     ` Kumar Gala
2007-01-15  6:37       ` Zhu Ebony-r57400
2007-01-15 14:37         ` Kumar Gala
2007-01-16  9:54           ` Zhu Ebony-r57400
2007-01-25  8:25           ` Zhu Ebony-r57400
2007-01-25  8:28             ` Kumar Gala
2007-01-25  8:53               ` Zhu Ebony-r57400
2007-01-25 15:10                 ` Kumar Gala
2007-01-26  6:16                   ` Zhu Ebony-r57400
2007-01-29 10:00                   ` Zhu Ebony-r57400
2007-01-29 14:30                     ` Kumar Gala
2007-01-31  9:45                       ` Zhu Ebony-r57400
2007-01-31 14:48                         ` Kumar Gala
2007-02-01  9:35                           ` Zhu Ebony-r57400
2007-02-07  5:52           ` Zhu Ebony-r57400
2007-02-07  7:11             ` Kumar Gala
2007-02-07  7:21               ` Zhu Ebony-r57400
2007-02-07  7:57                 ` Kumar Gala
2007-02-07  8:04                   ` Zhu Ebony-r57400
2007-02-08  3:50                   ` [patch][0/5] powerpc V2 : " Zhu Ebony-r57400
2007-02-08  5:18                     ` Kumar Gala
2007-02-08  5:40                       ` Zhu Ebony-r57400
2007-02-08  7:06                       ` Zhu Ebony-r57400
2007-02-08  7:15                         ` Kumar Gala
2007-02-08  8:08                           ` Zhu Ebony-r57400
2007-02-08 17:18                             ` Kumar Gala
2007-02-09  5:15                               ` Zhu Ebony-r57400
2007-07-30 14:56                                 ` Sergei Shtylyov
2007-07-31  3:36                                   ` Zhu Ebony-r57400

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