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Date: Thu, 19 Jul 2012 22:26:32 +0400
From: Solar Designer <>
Subject: Re: Keychain format OpenCL implementation, please review

Dhiru -

On Tue, Jul 17, 2012 at 10:16:48PM +0400, Solar Designer wrote:
> On Tue, Jul 17, 2012 at 10:02:05PM +0530, Dhiru Kholia wrote:
> > Speed is 132K c/s on ATI 6970. It is roughly 300x faster than
> > single-core CPU version (AMD X3 720). Hopefully, I haven't screwed
> > things up ;)
> I guess this means that your CPU code is a lot slower than it can/should
> be. ;-)  And your 140K c/s figure for 7970 (mentioned elsewhere)
> suggests that you might still be spending much time in CPU code, which
> is why changing the GPU makes little difference.

FYI, I am seeing 49% GPU usage when running your keychain-opencl code
currently in magnum-jumbo on FX-8120 and HD 7970.  This is a non-OpenMP
build.  So a 2x speedup might be possible with the same OpenCL kernel
by optimizing the CPU code and/or running it simultaneously with the GPU
code.  To better support the latter, I am going to introduce support for
"block IDs" into the formats interface, so that you could interleave two
such blocks.


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