Re: [eigen] Vectorized quaternion multiplication.

[Rohit Garg <rpg.314@xxxxxxxxx>]

On Sat, Mar 7, 2009 at 7:23 PM, Gael Guennebaud
<gael.guennebaud@xxxxxxxxx> wrote:
> committed :)
Thanks a lot for that. :). The quat add and sub are vectorized now as
well, I presume. {Damn the svn block. :( }

>
> On Sat, Mar 7, 2009 at 1:19 PM, Rohit Garg <rpg.314@xxxxxxxxx> wrote:
>> I think that the scalar version loses out because the multiplies are
>> not pipelined there.
>>
>> On Sat, Mar 7, 2009 at 5:30 PM, Rohit Garg <rpg.314@xxxxxxxxx> wrote:
>>> When you put it in, please tell me. :)
>>>
>>> I posted this for feedback here and you may be interested.
>>>
>>> http://forum.beyond3d.com/showthread.php?t=52840
>>>
>>> On Sat, Mar 7, 2009 at 5:16 PM, Gael Guennebaud
>>> <gael.guennebaud@xxxxxxxxx> wrote:
>>>> hi,
>>>>
>>>> thanks a lot,
>>>>
>>>> at a first glance I was not sure about the perf, because it needs a
>>>> lot of shuffle instructions which are quite costly, so benched, and on
>>>> my core2 your version is 1.5 times faster :) Then I changed the
>>>> shuffle_ps for the simpler PSHUFD instr. and now, it is almost 2x
>>>> faster, so really worth it :)
>>>>
>>>> FYI I only changed vec4f_swizzle like this:
>>>>
>>>> #define vec4f_swizzle(v,p,q,r,s) (_mm_castsi128_ps(_mm_shuffle_epi32(
>>>> _mm_castps_si128(v), \
>>>>  ((s)<<6|(r)<<4|(q)<<2|(p)))))
>>>
>>> Now I see. This instruction takes one operand alone so is perhaps
>>> faster (aka higher throughput).
>>>
>>> --
>>> Rohit Garg
>>>
>>> http://rpg-314.blogspot.com/
>>>
>>> Senior Undergraduate
>>> Department of Physics
>>> Indian Institute of Technology
>>> Bombay
>>>
>>
>>
>>
>> --
>> Rohit Garg
>>
>> http://rpg-314.blogspot.com/
>>
>> Senior Undergraduate
>> Department of Physics
>> Indian Institute of Technology
>> Bombay
>>
>>
>>
>
>
>



-- 
Rohit Garg

http://rpg-314.blogspot.com/

Senior Undergraduate
Department of Physics
Indian Institute of Technology
Bombay