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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 17:48:30 -0500
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To clarify, I meant separate backends, just like with SSE and NEON.
On Tue, Dec 6, 2011 at 5:09 PM, Rohit Garg <rpg.314@xxxxxxxxx> wrote:
> 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
--
Rohit Garg
http://rpg-314.blogspot.com/
Graduate Student
Applied and Engineering Physics
Cornell University