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Date: Sun, 5 Jun 2011 01:39:51 +0400
From: Solar Designer <solar@...nwall.com>
To: crypt-dev@...ts.openwall.com
Subject: Re: EskBlowFish with RAM results
Hi Yuri,
I am sorry that I am somewhat late to comment on this...
On Tue, May 31, 2011 at 12:40:23AM -0300, Yuri Gonzaga wrote:
> I am reporting the synthesis results for EsksBlowFish using RAM to pico e101
> device (Spartan-6 xc6slx45).
Great! Can you post the code, please?
> Slice Logic Utilization | Used | Available
...
> Number of Slice LUTs 8,059 27,288
Why so many LUTs?
> Number of occupied Slices 2,611 6,822
This is a consequence of the above...
So we'd fit only 3 EksBlowfish cores into that Spartan-6 chip, resulting
in worse than CPU performance. This shouldn't be so.
> Number of RAMB16BWERs 4 116
This makes more sense, but still I'd expect only 2 of these used. Why 4?
Are you keeping the initial constants in separate BlockRAMs? Or maybe P?
If so, the initial constants should be uploaded by the host, and P
should be in registers.
Anyhow, even at 4 16+2 Kbit BlockRAMs used per EksBlowfish, we could fit
29 cores in that chip. So we're clearly LUT-bound now, in terms of the
number of cores we can fit. Please look into reducing the LUT count,
which I think should be possible to reduce by a factor of 10 or more.
I really don't understand why you have so many LUTs used.
Thanks,
Alexander
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