OpenCL

[tzachi_cohen]

Hi ,

GCN GPUs are strict SIMT.

Decorating a kernel with '__attribute__((vec_type_hint(<type>)))' will not influence GPU compilation artifacts.

Since GCN is a scalar architecture, i.e. each thread can at most execute a single component ALU operation in a cycle there is no point in trying to horizontally-vectorize the code.

Tzachi

[savage309]

Thank you so much.

Just one more question - if I have to do a lot of transcedental functions over different data fields should I create my own ones (using polonomials that are close to the real ones), if I dont' care so much about the error ?

In other words, is it true that only the scalar unit can do transcedental functions ?

[tzachi_cohen · Accepted solution]

It is the opposite, transcendental functions are only supported on the vector engine, not  on the scalar engine.

They operate at quarter rate, hence if you want to have a faster approximation you need to do it in less than 4 single precision operations.

Tzachi

[nou]

I would benchmark it. Nothing is better than hard data.