# Sequential peakflops

**URL:** <https://discourse.julialang.org/t/sequential-peakflops/24066>\
**Category:** Performance\
**Created:** [May 10, 2019, 9:26am UTC](https://discourse.julialang.org/t/sequential-peakflops/24066 "2019-05-10T09:26:26Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![LaurentPlagne](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/laurentplagne/32/10103_2.png) [@LaurentPlagne](https://discourse.julialang.org/u/LaurentPlagne)\
**Post date:** [May 10, 2019, 9:26am UTC](https://discourse.julialang.org/t/sequential-peakflops/24066/1 "2019-05-10T09:26:26Z")

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Hi Julians,

When I use

```julia
peakflops(8000;parallel=false)

```

I obtain

```julia
1.266034664857239e11

```

which corresponds to (IMHO) the multicore peak perf of my PC.  
In addition I see top reaching 800%.  
The `parallel` flag seems to be ignored.  
Is it expected ?  
Best  
Laurent

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**Author:** ![kristoffer.carlsson](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kristoffer.carlsson/32/22_2.png) [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)\
**Post date:** [May 10, 2019, 2:27pm UTC](https://discourse.julialang.org/t/sequential-peakflops/24066/2 "2019-05-10T14:27:14Z")

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You can see what `parallel` does here: [https://github.com/JuliaLang/julia/blob/5486cc223c2b92b45d7d5e8e9cdbca9ffa49ab07/stdlib/LinearAlgebra/src/LinearAlgebra.jl#L400-L414](https://github.com/JuliaLang/julia/blob/5486cc223c2b92b45d7d5e8e9cdbca9ffa49ab07/stdlib/LinearAlgebra/src/LinearAlgebra.jl#L400-L414).

The matrix multiplication uses BLAS and will be multithreaded. `parallel` determines if multiple julia workers should be started.

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<div class="post-metadata">

**Author:** ![LaurentPlagne](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/laurentplagne/32/10103_2.png) [@LaurentPlagne](https://discourse.julialang.org/u/LaurentPlagne)\
**Post date:** [May 10, 2019, 2:36pm UTC](https://discourse.julialang.org/t/sequential-peakflops/24066/3 "2019-05-10T14:36:07Z")

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Thanx