Date: Thu, 03 Sep 2015 19:59:40 +0200 From: magnum <john.magnum@...hmail.com> To: john-dev@...ts.openwall.com Subject: Re: 23% performance regression for brypt (Intel i5-4570 CPU) On 2015-09-02 02:00, magnum wrote: > On 2015-04-12 12:14, Frank Dittrich wrote: >> Solar, >> >> you included the bcrypt related changes of bleeding-jumbo commit >> https://github.com/magnumripper/JohnTheRipper/commit/f64b42fee9e368cd85cf546f08b694510824fea2 >> >> into core, but decided to not allow BF_X2 = 3 for AVX systems. >> (I guess this is because on well BF_X2 = 3 causes about 5% performance >> regression.) >> >> But for my system (64bit Linux, i5-4570 CPU), this causes a 23% >> performance regression. > > Same here, on i7-3615QM (Ivy Bridge, AVX), OSX, gcc 4.9.2. Using X3 I > get 27% boost for a non-OMP build, 22% for OMP and while it's just 4% > boost for OMP+HT, it still is a boost. > >> May be you also reconsider allowing BF_X2 = 3 for AVX. > > If only well had a regression, perhaps decrease to X2 only for __AVX2__? > Or maybe this is also about gcc version? > >> Is there anything I can test, any more information you need to decide >> when BF_X2 should be 3 even for AVX, and when it shouldn't? > > https://github.com/magnumripper/JohnTheRipper/issues/1199 Some more tests on various gear: i7-4790 (core i7 Haswell, AVX2) gcc 4.8.2: Huge boost for X3 except when running HT (slight loss) E5-2699 v3 (Xeon Haswell, AVX2) gcc 4.8.2: Huge boost for X3 except when running HT (slight loss) E5-2670 (Xeon Sandy Bridge, AVX) gcc 4.8.2: Huge boost for X3, except with HT: Still a boost but very small. "Huge boost" again means 20-30% while "slight loss" means < 5%. magnum
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