Do 0.3 and 0.4 use the same number of threads by default? You could try calling blas_set_num_threads prior to peakflops to make sure. I get best results when the number of threads is equal to (or slightly less than, for 12 cores) the number of physical cores.
--Peter On Monday, February 2, 2015 at 9:58:23 AM UTC-8, Seth wrote: > > > > On Monday, February 2, 2015 at 9:43:50 AM UTC-8, Seth wrote: >> >> From https://github.com/JuliaLang/julia/pull/7662 I learned about >> peakflops(), so I decided to give it a try and am seeing very strange >> performance. >> >> On my Macbook Pro, I get 1.6950987382609034e9. This is slower than what's >> in the screenshot at the PR. >> Julia Version 0.4.0-dev+2529 >> Commit 322cf26* (2015-01-06 17:18 UTC) >> Platform Info: >> System: Darwin (x86_64-apple-darwin14.1.0) >> CPU: Intel(R) Core(TM) i7-3820QM CPU @ 2.70GHz >> WORD_SIZE: 64 >> BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY Sandybridge) >> LAPACK: libopenblas >> LIBM: libopenlibm >> LLVM: libLLVM-3.3 >> >> >> >> On my Mac Mini, I get 4.138266605094777e10 >> Julia Version 0.4.0-dev+2481 >> Commit 3735e01 (2015-01-04 18:57 UTC) >> Platform Info: >> System: Darwin (x86_64-apple-darwin14.0.0) >> CPU: Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz >> WORD_SIZE: 64 >> BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY Sandybridge) >> LAPACK: libopenblas >> LIBM: libopenlibm >> LLVM: libLLVM-3.3 >> >> >> >> Why would I be seeing worse performance from a quad-core i7 than a >> dual-core i5? >> >> >> > Sorry to follow up on my own post, but running v0.3.4 on the MBP seems to > brighten the picture considerably. Why is there such a difference between > 0.3 and 0.4? > > julia> peakflops() > 8.281406670627525e10 > > > julia> versioninfo() > Julia Version 0.3.4 > Commit 3392026* (2014-12-26 10:42 UTC) > Platform Info: > System: Darwin (x86_64-apple-darwin13.4.0) > CPU: Intel(R) Core(TM) i7-3820QM CPU @ 2.70GHz > WORD_SIZE: 64 > BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY Sandybridge) > LAPACK: libopenblas > LIBM: libopenlibm > LLVM: libLLVM-3.3 > >
