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Wireshark-dev: Re: [Wireshark-dev] Optimization

From: Mike Duigou <wireshark@xxxxxxxxxx>
Date: Fri, 26 Oct 2007 08:51:09 -0700
Using various machine settings as a way to improve performance is a common topic on Linux kernel discussion lists. The summary though from what I've read is that for almost all cases the various tunings between i386 and i686 SSE rarely make any appreciable difference at all. A few specific cases for atomic operations and 64-bit math do exist but they aren't heavily used enough to matter.

The Mozilla team came to a similar conclusion, that architecture optimization delivered nothing except incompatibility. They have actually switched to using code size optimization for most of the source base (resulting in a 3-5% reduction in executable size). They showed that having more code in the cache beat a speed optimized version in their standard test suites. Speed optimizations are used only for a few key routines. In some cases they recoded these routines so that they generated the almost the same code with or without optimization so as to get performance benefits on all supported platforms.

YMMV,

Mike

Anders Broman wrote:
Hi,
Would we get any performance gain by switching to /MACHINE:I686?
As we are no longer suporting older Windows versions there is no need to suport I386 I suppose…
Regards
Anders