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Message-ID: <20150620210430.GA10360@openwall.com>
Date: Sun, 21 Jun 2015 00:04:30 +0300
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: bcrypt-opencl local vs. private memory
magnum, Sayantan -
On Tue, Jun 16, 2015 at 05:06:40PM +0300, Solar Designer wrote:
> Sayantan took care of this at the time, in commit
> 97545b7ab51a4e8ddccba1a098f5448d808ae39b which includes:
>
> #if gpu_nvidia(DEVICE_INFO)
> #define MAYBE_LOCAL __private
> #else
> #define MAYBE_LOCAL __local
> #endif
>
> I've just tested this on our GTX 570 as well, and unfortunately it
> actually hurts performance there. (Even though it was helping on our
> TITAN a bit.) With the above commit, I am getting around 400 c/s.
> With forced use of __local, it's around 1200 c/s.
>
> I merely want to document this in here. I am not suggesting making any
> further change yet. Either of these speeds is quite low anyway.
>
> I am currently discussing bcrypt on GPU with Alain (via off-list
> e-mail), who managed to achieve much higher speeds anyway, including on
> his GTX 590 (per GPU).
(Un)fortunately, Alain's initial results that I mentioned above were
wrong. So no "much higher speeds" for us. I think we need to fix the
original issue described above somehow. magnum, can we possibly have
this local vs. private bit autodetected along with GWS and LWS?
Alexander
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