Looking at code_llvm(sumofsins2, (Int,)), it looks like sin(3.4) used to be constant collapsed [1], but is now recomputed each time through the loop.
[1] That's the 0xBFD05AC910FF4C6C in the LLVM code in John's post reinterpret(Float64, 0xBFD05AC910FF4C6C) == -0.2555411020268312 == sin(3.4) On Monday, January 26, 2015 at 11:23:36 PM UTC-8, Mauro wrote: > > This is a performance regression, also for 0.3.5. My timings for 0.3.5: > > > julia> @time [sumofsins1(100_000) for i in 1:100]; > elapsed time: 0.446675737 seconds (320109932 bytes allocated, 21.32% gc > time) > > julia> @time [sumofsins2(100_000) for i in 1:100]; > elapsed time: 0.115537618 seconds (896 bytes allocated) > > > but for 0.2.1: > julia> @time [sumofsins1(100_000) for i in 1:100]; > elapsed time: 0.347052858 seconds (320072020 bytes allocated) > > julia> @time [sumofsins2(100_000) for i in 1:100]; > elapsed time: 0.008610216 seconds (896 bytes allocated) > > > Can you check whether an issue for this has been filed and if you can't > find one file one? > > On Tue, 2015-01-27 at 07:36, Kuba Roth <kuba...@gmail.com <javascript:>> > wrote: > > Hi there, > > Recently I run into this very interesting post: > > > http://www.johnmyleswhite.com/notebook/2013/12/06/writing-type-stable-code-in-julia/ > > > > > Surprisingly, when tested both examples against the latest 0.4 build - > the > > speed difference of the type-stable version is only 2-3 times faster > then > > unstable one. > > I wonder what is the source of such a huge disparity and what version of > > Julia was used? > > > > My timings: > > unstable: 0.425013212 seconds (305 MB allocated, 7.56% gc time in 14 > pauses > > with 0 full sweep) > > stable: 0.14287404 seconds (896 bytes allocated) > > > > John's: > > unstable: 0.412261722 seconds (320002496 bytes allocated) > > stable: 0.008509995 seconds (896 bytes allocated) > > > > Thanks, > > kuba > >
