Date: Thu, 17 Sep 2015 01:29:49 +0300 From: Solar Designer <solar@...nwall.com> To: john-dev@...ts.openwall.com Subject: Re: multi-threaded hash table initialization On Thu, Sep 17, 2015 at 01:18:41AM +0300, Solar Designer wrote: > I think we can commit it and give it some more testing. There might be > regressions for other cases, especially multi-salt with small per-salt > hash tables - maybe we need to add a check for that (would need to come > up with a hash table size threshold). Also, maybe we need to require at least 6 original threads before we use our 3 threads. So change: if (john_omp_threads_orig < 3) goto single_threaded; to: if (john_omp_threads_orig < 6) goto single_threaded; so that we don't go for the multi-threaded approach on dual-core with 2 hardware threads/core, where the 3 threads would end up sharing 2 physical cores, and with them doing some duplicate work they'd likely end up running slower than the single-threaded code. OTOH, there are also perfectly fine quad-core systems without SMT, where the multi-threaded approach is likely beneficial. So I'm not sure. Alexander
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