Takehiro hack

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Stoner, Michael

Takehiro hack

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Hello,
I'm doing some performance analysis for Intel and I'd like to know if
most users are building LAME with the Takehiro magic float hack enabled?
I found that disabling the hack improved my encode time by about 15%.  I
used the VC++ 2005 compiler with /arch:SSE2 and /fp:fast switches.

Here's my data running on Nehalem 2.8 Ghz and Merom 2.93 Ghz cores:

Workload:  lame.exe -h -b160 --nores  file.wav

                                                  NHM MRM
Baseline w/ Takehiro hack - 50 sec 51 sec
Hack + /fp:fast /arch:SSE2 - 46 sec 47 sec
w/o Hack + /fp:fast /arch:SSE2 - 41 sec 40 sec


Thanks,
Mike Stoner
Intel Software Solutions Group
Folsom, CA
(916) 356-9414


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Robert Hegemann

Re: Takehiro hack

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Hello Mike,

Am 26.06.2008, 03:34 Uhr, schrieb Stoner, Michael  
<[hidden email]>:

> Hello,
> I'm doing some performance analysis for Intel and I'd like to know if
> most users are building LAME with the Takehiro magic float hack enabled?

I would say it's in 99 percent the case. The others are those users
that own something different from a x86 system.

> I found that disabling the hack improved my encode time by about 15%.  I
> used the VC++ 2005 compiler with /arch:SSE2 and /fp:fast switches.

My own speed tests were some time ago, but if I remember correct,
enabling SSE2 was a good way to make LAME running slower (using VC2005).

> Here's my data running on Nehalem 2.8 Ghz and Merom 2.93 Ghz cores:
>
> Workload:  lame.exe -h -b160 --nores  file.wav
>
>  NHM MRM
> Baseline w/ Takehiro hack - 50 sec 51 sec
> Hack + /fp:fast /arch:SSE2 - 46 sec 47 sec
> w/o Hack + /fp:fast /arch:SSE2 - 41 sec 40 sec
>
>
> Thanks,
> Mike Stoner
> Intel Software Solutions Group
> Folsom, CA
> (916) 356-9414


Ciao Robert

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