Date: Thu, 9 Jul 2015 13:59:20 +0300 From: Solar Designer <solar@...nwall.com> To: john-dev@...ts.openwall.com Subject: Re: JtR on Power On Thu, Jul 09, 2015 at 12:00:41PM +0800, Lei Zhang wrote: > I pick a few representative formats here to demonstrate the difference after using AltiVec: I wouldn't call these formats representative (they are fast hashes), and these are poor speeds either way. Can you show md5crypt, phpass, sha256crypt, sha512crypt? And PBKDF2-*? > Strangely, MD5, SHA256 and SHA512 become even slower. I don't know what exact CPUs you're on, but I suspect they are designed to run 4 or 8 threads/core (for POWER7 and POWER8, respectively), and the impact from not doing so might be more profound for SIMD instructions (higher latency) than for scalar ones. So you might need to be doing multi-threaded benchmarks for the slow hashes, but you also need to be very careful about possible other load on the system. If there is any, then you'd need to set OMP_NUM_THREADS and possibly GOMP_CPU_AFFINITY to get yourself some otherwise free cores. To set GOMP_CPU_AFFINITY right, you'd first need to figure out the system's mapping of logical CPUs to physical cores. In fact, GOMP_CPU_AFFINITY spanning the whole range might be needed even on an otherwise idle system, as we're seeing on "super". Alexander
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