[rfc] improving 32bit user performance/experience...

Daniel J Blueman daniel.blueman at gmail.com
Mon May 18 23:24:17 UTC 2009

A number of benchmarks show a significant performance loss on 32bit
ubuntu over 64bit [1], on the same hardware. This is partially due to
restrictions on the instruction set and partially due to worse
instruction scheduling (others reasons include register width and
count, for moving data and calling convention).

Just how much user experience do we trade away for i386/i486 legacy
compatibility these days?

If (eg) 1.0% of 32bit Ubuntu users have i586-only processors, how
about setting the default compile flags to -march=i586 and
-mtune=pentium3 in principle?

This seems like good value to tweak end-user performance/experience a
bit, am I missing something, or should we just not care?

(does any of this apply to x86-64, eg -mtune=core2 or k8?)

--- [1]

Daniel J Blueman

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