Date: Thu, 2 Feb 2012 06:41:46 +0400 From: Solar Designer <solar@...nwall.com> To: john-dev@...ts.openwall.com Subject: Re: Adding a new format On Tue, Jan 31, 2012 at 11:41:27PM +0100, magnum wrote: > On 01/31/2012 11:10 PM, Claudio Broglia wrote: > > - would you suggest to crypt many keys at every pass, to gain speed, or > > to stick with MAX_KEYS_PER_CRYPT set to 1? > > If you calculate one hash at a time (like in an OpenSSL version) there > is no gain in rasing it. Actually, there may be some minor gain from reduced function call overhead (one call per N hashes vs. one call per 1 hash) and from potentially improved locality of reference - especially if L1 instruction cache is direct-mapped or has low associativity - like what we had on Alpha and like what we apparently have on AMD Bulldozer now. Speaking of the latter, according to what I read Bulldozer's instruction cache is 2-way, but shared for two cores in a module and with 1 way per core - which I interpret as it being effectively direct-mapped. If so, we may get large slowdowns on certain builds/runs where pieces of code from different source files, but used inside the cracking loop happen to get overlapping cache tags. Alexander
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