Re: [ViennaCL-devel] Performance GPU/CPU weirdness

[Sensei <sen...@gm...>]

> On Feb 19, 2017, at 12:14am, Oswin Krause <Osw...@ru...> wrote:
> 
> Hi,
> 
> I would argue you have some serious problem with your setup if copying of 1MB takes time in the order of minutes (and even if its milliseconds, i would consider this as way too much).

Hi Oswin, 

Yes, I believe there is a problem, but I don’t know what to debug.

> I am also concerned that your new cpu timing is 0.

Why? Caching is a good cause for just 1M items.

> that resizing takes longer on a gpu is expected as you are doing something way more complicated when allocating storage on the gpu, compared to a cpu.
> 
> Also consider doing some real work. computing the norm of a 1MB vector is not really something one would consider the gpu for. All simple vector operations/reductions are a pain to get fast on a gpu. compare matrix-matrix multiplications or similar.


Thanks, I will try ASAP with more complex operations.

Thank you!