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Date: Fri, 18 May 2012 20:52:24 +0800
From: myrice <qqlddg@...il.com>
To: john-dev@...ts.openwall.com
Subject: About Performance of Store Loaded Hashes/Salts on GPU

Hi Solar, Samuele,

The performance gains from storing loaded hashes/salts on GPU is
mainly from reducing hashes/salts transfer from CPU to GPU I think.
Here is q quick test I have done.
Current xsha512-opencl/xsha512-cuda have cmp_all() on GPU. The
hashes/salts are transferred to GPU when we invoke
cmp_all()/crypt_all() respectively. So I commented out the hashes and
salts copy code in cmp_all() and crypt_all(). Here is the result:
Before:
[11:36:43 myrice] run $ ./john -te=1 -fo=xsha512-cuda
Benchmarking: Mac OS X 10.7+ salted SHA-512 [CUDA]... DONE
Many salts:     65278K c/s real, 65278K c/s virtual
Only one salt:  28973K c/s real, 28973K c/s virtual

After:
[11:36:43 myrice] run $ ./john -te=1 -fo=xsha512-cuda
Benchmarking: Mac OS X 10.7+ salted SHA-512 [CUDA]... DONE
Many salts:     65925K c/s real, 65925K c/s virtual
Only one salt:  29491K c/s real, 29230K c/s virtual

It seems these copys do not hurt performance a lot. Any ideas about this?

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