Linux-kernel mailing list archive 1997-49,: Re: copy-bit macro

# Re: copy-bit macro

mharris@ican.net
Fri, 12 Dec 1997 13:02:19 -0500 (EST)

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On 11 Dec 1997, Stefan Monnier wrote:

> Date: 11 Dec 1997 17:59:10 -0500
> From: Stefan Monnier
<monnier+lists/linux/kernel/news/@TEQUILA.SYSTEMSZ.CS.YALE.EDU>
> To: linux-kernel@vger.rutgers.edu
> Newsgroups: lists.linux.kernel
> Subject: Re: copy-bit macro
>
> "Theodore Y. Ts'o" <tytso@MIT.EDU> writes:
> > (1 << OUT_FLAG_NUMBER) : 0") both involve an assembly language
> > conditional jump instruction, which is expensive, because it involves
> > pipeline stalls, etc.
>
> Has it been measured ? I know that branch prediction is not 100%, but
> I'm just trying to make sure we're not trying to solve a non-problem (if the
> prediction works well, then the jump costs 0 (zero) cycles).

386/486 processors have branch prediction?

Mike A. Harris | Homepage: http://blackwidow.saultc.on.ca/~mharris
Computer Consultant |
System/Network Administrator - John Howard Society, Sault Ste. Marie, Ont.
Mark should get a sound card and more ISA slots!!!!!!!! ;o)

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