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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] Status of AVX support
- From: Rohit Garg <rpg.314@xxxxxxxxx>
- Date: Tue, 6 Dec 2011 17:09:52 -0500
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On Tue, Dec 6, 2011 at 8:01 AM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote:
> Hi,
>
> I don't know of any work in that direction.
>
> The difficulty is that taking advantage of AVX without regressing
> current performance from SSE will require us to handle *both* 16-byte
> and 32-byte packet size and alignment. We will need 16-byte for e.g.
> Vector4f, while we will of course want to use 32-byte wherever we can.
>
> That part requires significant changes in Eigen.
But that will still need the AVX and SSE backend to choose on a per
object basis, right?
>
> On the other hand, if you can be satisfied with just a pure-32-byte
> mode, not trying to fall back to 16-byte, that's a lot easier, you'd
> just have to adjust existing code to allow for 32-byte alignment
> instead of 16-byte (easy) and add arch/AVX/PacketMath.h (not hard if
> you know AVX intrinsics). You're welcome to do so, but keep in mind
> that such a pure-32-byte mode will regress performance for the
> applications that don't lend themselves well to 32-byte packets and
> alignment, such as Vector4f, so it won't be possible to enable it by
> default until it can properly fall back to 16-byte packets and
> alignment.
>
> Cheers,
> Benoit
>
> 2011/12/5 Rohit Garg <rpg.314@xxxxxxxxx>:
>> Hi,
>>
>> I just laid my hands on a Sandy Bridge machine and I was wondering
>> what is the current status of AVX development for Eigen.
>>
>> Cheers,
>> --
>> Rohit Garg
>>
>> http://rpg-314.blogspot.com/
>>
>> Graduate Student
>> Applied and Engineering Physics
>> Cornell University
>>
>>
>
>
--
Rohit Garg
http://rpg-314.blogspot.com/
Graduate Student
Applied and Engineering Physics
Cornell University