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DateMon, 28 Jul 1997 22:43:42 +0200 (MET DST)
From"Michael L. Galbraith" <>
SubjectRe: Interesting pentium-memcpy results
On Mon, 28 Jul 1997, Benjamin Saller Bender wrote:

> Chris Evans <mailto:chris@ferret.lmh.ox.ac.uk> writes:
>        >I just compared 2.1.46 vs. 2.1.46+pentium memcpy patch, and interestingly
>     >enough found that the UNIX byte benchmarks tended to _drop_ a fair bit,
>     >with the exception of process creation and execl throughput. (Note that I
>     >only ran the basic 'system' tests - TCP bandwidth etc. to be determined
>     >when I find the newer benchmarks)
>     >
> 
>     >It does however show us that there still is performance to be gained. I
>     >presume the process creation test will be using fork() which does a lot of
>     >memcpy'ing of various process credentials in kernel space.
>     >
>    	I haven't done the research to verify how well this will work under 
> Linux, but for large a memcpy on the P5 we may wanna consider using the FP 
> unit using double precision read and writes. I have sample code if anyone is 
> interested. 
> -- 
> Benjamin Saller Bender 			<case@AppliedTheory.com>
> AppliedTheory Communications		Software Engineering Group
> http://AppliedTheory.com/               Sentio aliquos togatos contra me conspirare.
> 
> 
> 

I have done a lot of benching with it.. it's a big win here except for X 
mostly. There are places where it doesn't win.. ergo why it's not in the
kernel tree?.. but it wins a LOT more than it loses here.

	-Mike


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