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Message-ID: <20150817144119.GA31572@openwall.com>
Date: Mon, 17 Aug 2015 17:41:19 +0300
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: FMT_OMP_BAD
On Mon, Aug 17, 2015 at 05:23:55PM +0300, Solar Designer wrote:
> It is weird that Raw-SHA1 and Raw-SHA1-ng would be treated differently,
> even though they are in fact on different sides of the 4.0 threshold:
>
> Ratio: 3.13780 real, 0.31346 virtual Raw-SHA1:Raw
> Ratio: 4.45613 real, 0.46748 virtual Raw-SHA1-ng, (pwlen <= 15):Raw
>
> I've just confirmed this with some benchmarks I ran. The most important
> difference between these two is that -ng is limited to handling
> passwords of up to 15 characters long only, which allows it to run
> slightly faster. I'm unsure whether we want to add the compile-time
> default for OpenMP support into the mix as well or not. I think our
> options are: disable OpenMP by default only for Raw-SHA1 (as per the 4.0
> threshold) or for both Raw-SHA1 and Raw-SHA1-ng (to treat them the
> same). I think I'd prefer us to do the latter. Another reason to treat
> them the same is that I suspect the better performance of -ng would be
> less profound when running on a currently typical end-user machine with
> 4 physical cores and 8 logical CPUs. (We may confirm this.)
>
> I'd like magnum's comments on this.
Actually, both are already in the FAST_FORMATS_OMP category:
[solar@...er src]$ fgrep FAST_FORMATS_OMP rawSHA1_*.c
rawSHA1_fmt_plug.c:#if !FAST_FORMATS_OMP
rawSHA1_ng_fmt_plug.c:#if !FAST_FORMATS_OMP
So we just keep them in there.
Alexander
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