# Building Julia: Does the compiler matter?

**URL:** <https://discourse.julialang.org/t/building-julia-does-the-compiler-matter/6858>\
**Category:** Performance\
**Tags:** mkl, build\
**Created:** [November 3, 2017, 10:36am UTC](https://discourse.julialang.org/t/building-julia-does-the-compiler-matter/6858 "2017-11-03T10:36:56Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![carstenbauer](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/carstenbauer/32/4981_2.png) [@carstenbauer](https://discourse.julialang.org/u/carstenbauer)\
**Post date:** [November 3, 2017, 10:36am UTC](https://discourse.julialang.org/t/building-julia-does-the-compiler-matter/6858/1 "2017-11-03T10:36:56Z")

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I want to use Julia with MKL. As has been discussed, one currently has two options: use Julia Pro or build Julia from sources and setting flags. For many reasons I want to take the second approach.

Regarding performance, what compiler should I use to build Julia, icc or gcc? Does the choice influence performance at all. [Here](https://discourse.julialang.org/t/building-julia-0-6-0-with-mkl-on-osx-10-12-5/5073/5) it has been mentioned that “Code generation is doen by LLVM so runtime performance AFAIU, run time performance should not depend on what you use to compile LLVM / Julia with.”

Is that true? Any ideas?

Using gcc is often more convenient and as far as I know automatically tested by the Julia team.

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**Author:** ![yuyichao](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/yuyichao/32/20_2.png) [@yuyichao](https://discourse.julialang.org/u/yuyichao)\
**Post date:** [November 3, 2017, 5:41pm UTC](https://discourse.julialang.org/t/building-julia-does-the-compiler-matter/6858/2 "2017-11-03T17:41:21Z")

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Performance wise, it shouldn’t really matter for all of the fast paths. Slow paths where this could matter includes parsing/dispatch/allocation/GC/codegen though if any of these takes significant time in your application, gcc vs icc would likely be the last thing you need to worry about.

I remember something about ifort/mkl abi compatibility issue but I have 0 idea what those are but it shouldn’t be a fundamental issue if it’s an issue at all. People that have actually build julia with MKL should know much better…

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**Author:** ![carstenbauer](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/carstenbauer/32/4981_2.png) [@carstenbauer](https://discourse.julialang.org/u/carstenbauer)\
**Post date:** [November 4, 2017, 7:20pm UTC](https://discourse.julialang.org/t/building-julia-does-the-compiler-matter/6858/3 "2017-11-04T19:20:08Z")

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Thanks for the response!

By now, I’ve done a quick check for my particular application (a Quantum Monte Carlo code) and it appeared to not matter at all.

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**Author:** ![Juan](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/juan/32/7657_2.png) [@Juan](https://discourse.julialang.org/u/Juan)\
**Post date:** [November 19, 2018, 7:11pm UTC](https://discourse.julialang.org/t/building-julia-does-the-compiler-matter/6858/4 "2018-11-19T19:11:44Z")

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