Date: Thu, 27 Sep 2012 08:01:07 +0200 From: magnum <john.magnum@...hmail.com> To: john-dev@...ts.openwall.com Subject: Re: sha512crypt-opencl On 27 Sep, 2012, at 0:06 , Claudio André <claudioandre.br@...il.com> wrote: > Hi, thanks again. > > 2012/9/26 Gifts <gifts.antichat@...il.com> > Benchmark with 20 minutes JtR and 10 minutes cudaHashcat > > And it is interesting, that Intel OpenCl SDK can't vectorize this > kernel. I hadn't look deeply into code yet, was this kernel optimized > for GPU? > > > > I suppose magnum have something interesting to say about Intel SDK. Let's hear from him. > > I don't have any Intel hardware, so i can't say anything useful. Nevertheless, the kernel that runs on CPU is not optimized for GPUs. It gives acceptable results on AMD CPUs (i would say it was optimized for it). > > Maybe, there are tricks one can use to help the Intel compiler "do the job". Anyone have any clues about it? > > Claudio I have seen Intel SDK auto-vectorize code that did not have any "hints" nor used vector types. That's impressing. I have also seen (judging from performance) Intel fail to vectorize code that is very simple and that do use vector types. That's a lot less impressing, even annoying. AMD APP seems to handle the latter case better. Note that this is regardless of hardware - you can use Intel SDK with AMD hardware or vice versa. I use to install both on any hardware that does not have a GPU. Another caveat: I've seen indications that when Intel reports "kernel <xyz> was not vectorized" while building, it only means it was not auto-vectorized from scalar source. I mean, if the code does use vector data types it hopefully ended up as SIMD code despite that message. This is confusing, I'd rather have it silent. magnum
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.