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From Egor Pasko <egor.pa...@gmail.com>
Subject Re: [perf] Comparative benchmarking
Date Wed, 07 Nov 2007 06:21:51 GMT
On the 0x387 day of Apache Harmony Aleksey Shipilev wrote:
> On 07 Nov 2007 00:27:25 +0300, Egor Pasko <egor.pasko@gmail.com> wrote:
> > Vladimir, guess what? :) I actually mixed several things
> > altogether.
> <giggly>(sigh) As usual, miracle does not happen :) I dreamed to see
> software sqrt() implementation that could be faster than hardware one.
> </giggly>
> 
> > So, we are left with SSE asm that can be inlined by JIT and AFAI can
> > see it is not as fast as HotSpot? Weird :)
> No, for now we have just the intrinsic in native code, so we also have
> overheads for JNI transition (and it is heavy!), parameter passing,
> chains of calls, etc. I believe that sqrt() magic will lead that NBody
> performance very close to RI.

Ha! I thought, you made it without JNI. Then we have a chance! If we
do not get it through magics we still have another chance to implement
1/sqrt() :)

> BTW, in my thought this benchmark is like the top of the iceberg
> called "FP performance problems".

Yes, I know, DRLVM has not been actively optimized for FP calc.

-- 
Egor Pasko


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