Re: Perf patches, libmpg123 patches, and a new release of LAME?

Quoting Alexander Leidinger <[email protected]> (from Thu, 07  
May 2020 09:20:29 +0200):

> Quoting Gabriel Bouvigne <[email protected]> (from Wed, 06 May  
> 2020 09:54:01 +0000):

>> Regarding the perf patches:
>>
>> - Takehiro IEEE754 hack
>> It indeeds slows things down on most of the modern processors (at  
>> least on current AMD processors, and all of the i3/i5/i7 line from  
>> Intel), and it has been this way for at least 10 years. I am  
>> however not sure about its performance impact on low-grade Intel  
>> processors (the current "Pentium" and Atom line, which are  
>> significantly different from the i3/5/7 line).
>> I see two options there:
>> a) keep the hack code, but conditionnaly enable it based on target  
>> processor.
>> b) totally disable the hack.
>>
>> Unless we have the ability to test the speed benefits on Pentiums  
>> and Atoms beforehand, a good option might be to:
>> *for next version, keep the code, but globally disable the hack
>> *based on eventual field reports, decide if we should remove the  
>> code for the next next version
>
> That is what I had in mind myself. I'm a little bit indifferent if I  
> should provide a configure option to enable it or not.

I had a look at this, we enable this for powerpc, i386 (= 32 bit  
Intel), and amd64/x86_64.
I do you think about keeping it enabled on i386, and maybe powerpc  
(well... no idea if a recent powerpc CPU would benefit either way),  
and disabling it on amd64/x86_64? Does this make sense to you?

Bye,
Alexander.

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