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Date: Fri, 21 Aug 2015 09:16:00 +0800
From: Kai Zhao <loverszhao@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: BENCHMARK_LENGTH bugs

On Fri, Aug 21, 2015 at 1:30 AM, magnum <john.magnum@...hmail.com> wrote:
> On 2015-08-20 19:13, Kai Zhao wrote:
>>
>> On Mon, Aug 17, 2015 at 11:22 PM, Solar Designer <solar@...nwall.com>
>> wrote:
>>>
>>> Also, identify formats that wrongly set BENCHMARK_LENGTH to 0 when they
>>> don't actually need to report separate "Many salts" vs. "Only one salt"
>>> speeds (that is, formats that are very slow or/and saltless, so the two
>>> speeds reported are nearly the same anyway).
>
>
>>
>> I create a patch for benchmark_length:
>>
>>
>> https://github.com/loverszhaokai/JohnTheRipper/commit/810a62c938d86a724f5398d312bbb1c5736a1147
>
>
>> Testing: 7z, 7-Zip (512K iterations) [SHA256 AES 32/64]... (8xOMP)
>> FAILED (This format is very slow, but it will report separate "Many
>> salts" vs. "Only one salt" speeds)
>
>
> Your patch has a hard-coded list of "slow hashes". That's not good
> from any point of view. As seen in the above figures, you should do
> calculate a figure many/one like this:
>
>> $ ../john --test --format=7z
>>
>> Will run 8 OpenMP threads
>> Benchmarking: 7z, 7-Zip (512K iterations) [SHA256 AES 32/64]... (8xOMP)
>> DONE
>> Speed for cost 1 (iteration count) of 524288
>> Many salts: 3056 c/s real, 3034 c/s virtual
>> Only one salt: 18.0 c/s real, 18.1 c/s virtual
>
>
> 3056/18 = 169.78x faster. Definitely nothing to complain about.
>
>> $ ../john --test --format=dominosec8
>>
>> Will run 8 OpenMP threads
>> Benchmarking: dominosec8, Lotus Notes/Domino 8 [8/64]... (8xOMP) DONE
>> Warning: "Many salts" test limited: 1/256
>> Many salts: 3471 c/s real, 435 c/s virtual
>> Only one salt: 3303 c/s real, 416 c/s virtual
>
>
> 3471/3303 = 1.05x so a 5% speedup. I'm not sure we should complain even
> here.
>
> I think you should complain if speedup is less than 1-2%. Also, I'm not sure
> you should FAIL but maybe just "Warning: ..." like with alignment issues.
> Solar?

I think I misunderstood the "slow" which I thought it was the formats
whose real speed was small. As magnum said, the "slow" means
the speedup from "Only one salt" to "Many salts" is less than 1-2%.

But there are many formats whose benchmark_length is '-1', and they
only have "Raw" speed. How to judge whether these formats are slow?


Thanks,

Kai

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