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List:       freebsd-hackers
Subject:    Re: SSE bcopy etc.
From:       Mike Smith <msmith () FreeBSD ! ORG>
Date:       2001-12-29 1:20:08
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>     Has anyone considered adding Pentium 2/3/4/Athlon/Athlon XP support 
> to the low level string/bytecopy routines? If we just supported SSE (1) 
> that'd get us (okay, me) a pretty nice performance boost on the P2, P3, 
> P4 and Athlon XP, all in one hit. These days, the "average" new computer 
> supports SSE, and since the GCC 3.x/binutils folk are on their way to 
> supporting this stuff in a Standard way (e.g. '-msse', '-march=athlon' 
> etc.) maybe it's time to code something up?

This is less of a win than it seems, since it means that you have to
save/restore FPU context if the current process is using the FPU.
These saves are expensive, and mean that the SSE-enhanced copy is only
faster for large-ish copies.  Page-sized copies and zeroes would be
improved substantially.


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