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Date: Sun, 6 Sep 2015 11:56:01 +0300
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: PHC: Argon2 on GPU

Agnieszka,

On Sat, Sep 05, 2015 at 09:17:47PM +0200, Agnieszka Bielec wrote:
> argon2d using ulong4 vectors when accessing global memory

Cool.  Thank you for doing this!

I think the next task is to get rid of any spilling to global memory.
If we do have to store something in global memory, we should choose what
that is explicitly.

On NVIDIA, we're warned by ptxas whenever there's spilling.

On AMD, we can build with:

AMD_OCL_BUILD_OPTIONS_APPEND=-save-temps

and find the summary near the end of the _temp_*.isa file, e.g. for our
md5crypt-opencl:

codeLenInByte        = 16092 bytes;

NumVgprs             = 25;
NumSgprs             = 30;

ScratchSize          = 148 dwords/thread;
LDSByteSize          = 0 bytes/workgroup (compile time only);

We should bring ScratchSize to zero.

Alexander

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