A problem about openblas threads?

[zazd]

I use openblas and in the demo, the code that: caffeMobile.setNumThreads(4); and in the jni: openblas_set_num_threads(num_threads);

I seems that this change the number of cores that we use. However, when I change the number in setNumThreads(), from 1-6. It changes nothing. For example, it cost me 5s to run a image when the number is 1, and 5s as the number is 4(or others).

My arm has 6 cores.

So, would you tell me something about the function setNumThreads()?

Thank you!

[sh1r0]

For OpenBLAS with libs on armeabi-v7a, I had tested that the number of threads do effect the performance.

[zazd]

I try it again just a moment ago. But it still seems nothing changed.

what I do: export USE_OPENBLAS=1 export ANDROID_ABI="armeabi-v7a-hard-softfp with NEON" ./build.sh <path/to/ndk>

[sh1r0]

Did you try the prebuilt libs in this repo before? I'm pretty sure that it works with openmp support.

[zazd]

what is "the prebuilt libs "? and where can I find it?

[sh1r0]

https://github.com/sh1r0/caffe-android-demo/tree/master/app/src/main/jniLibs

[zazd]

Yes, I always do it, but find ineffective. I run this demo in TK1, but find that it always run the program in one cpu core(and in other devices like rk3288 or xiaomi box3, it is ineffective when changed the number of openblas threads, too). I make a test in TK1 of Matrix multiplication. I find that even I make sure that I have 4 threads, the time it cost is the same as 1 thread. It seems that TK1 has only a core to calculate the floating point(I guess).

So, would you tell me, what device you use when it do effect the performance ?

[sh1r0]

Sorry, I found that I made a mistake and thus caffe libs would be built with eigen by build.sh even USE_OPENBLAS=1 is set. Therefore, the prebuilt libs were all built with eigen instead of openblas. I fixed the bug in the dev branch of caffe-android-lib. As it is time-consuming to rebuild the libs for all abi, please build caffe-android-lib on your own. Sorry again for the inconvenience.

[zazd]

Could tell me the mistake so I can build the lib by myself? I am not familiar with shell so I cannot find it. Thank you!

[zazd]

I find it. I delete build_eigen.sh in build.sh. And just use build_Openblas.sh. It works. Thank you!