Re: [Discuss-gnuradio] performance improvements and using volk

[Nick Foster]

On Tue, Nov 8, 2011 at 6:58 PM, Tom Rondeau <address@hidden> wrote:
> On Tue, Nov 8, 2011 at 9:08 PM, Josh Blum <address@hidden> wrote:
>>
>> Hey list,
>>
>> I have been itching to make some new gnuradio blocks that make use of
>> volk. So to avoid disturbing the delicate balance of code in
>> gnuradio-core, I have produced a new component called gr-basic.
>>
>> The goal of gr-basic is to replace many of the blocks in gnuradio-core
>> with vector optimized blocks that call into volk; and to make it easy
>> for users to extend blocks to support new data types. You can see the
>> branch here: http://gnuradio.org/cgit/jblum.git/log/?h=gr_basic
>>
>> So far, gr-basic has the familiar add, multiply, subtract and divide
>> block, but with 2 major differences:
>>
>> 1)
>> It is very easy to add new data types to these blocks. So it doesn't
>> suffer from the confusing code generation or naming convention issues
>> with the existing adder. So rather than generating gr_add_* for each
>> data type, there is one block add, which takes as a parameter, the data
>> type.
>>
>> 2)
>> Some of the adder implementations use volk routines. We happened to
>> already have a volk routine for adding floats, so rather than calling
>> into the generic implementation, we call into a work function that calls
>> the volk add routine, seen here:
>>
>> http://gnuradio.org/cgit/jblum.git/tree/gr-basic/lib/gr_basic_add.cc?h=gr_basic#n45
>>
>> Just as a rough benchmark, you can expect a 30% savings in overhead from
>> the adder (tested on a sse machine).
>>
>> I hope that this gives users a good starting point for optimizing
>> gnuradio blocks with volk!
>>
>> -Josh
>
> So I like everything about this but the name.  We could stuff all of this
> under the "gnuradio.gr" namespace in Python, or we could name this
> "gr-math."
> Actually, while I was typing this, I'm thinking we rename the directory to
> be "gr-blocks" but put them under the "gnuradio.gr" namespace. I'm expecting
> that since you've used different names for the blocks because of the
> data-type handling that they won't collide with what's in guradio-core right
> now.
> Thanks!
> Tom

The best part is it took Josh and I longer to figure out what to call
it than it took Josh to code it up.

--n

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