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Message-ID: <20120327062713.GA13878@openwall.com>
Date: Tue, 27 Mar 2012 10:27:13 +0400
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: [JtR patch] Fast cracker for Mozilla Firefox, Thunderbird and SeaMonkey master passwords.
On Mon, Mar 26, 2012 at 10:56:09AM +0200, magnum wrote:
> I can't see any obvious reason it doesn't scale better either - it
> spends 95% in (and below) crypt_all() where everything should be MT. But
> I only get 161% when running on two threads. I think this format is slow
> enough to scale much better than that.
I haven't looked into this at all, but the above suggests that the
problem is in memory access patterns (maybe false sharing) or/and in too
frequent thread synchronization (busy waiting).
http://en.wikipedia.org/wiki/False_sharing
Alexander
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