Disable SSE4.1 when compiling TensorFlow - tensorflow

I followed the instruction on TF's website and install the TensorFlow from the source code. I did not change any configurations, all are the default values.
When I run my program (which works fine when using the pre-complied TensorFlow 0.12 wheel), it gives me the following error
F tensorflow/core/platform/cpu_feature_guard.cc:86] The TensorFlow library was compiled to use SSE4.1 instructions, but these aren't available on your machine.
By default TensorFlow enables SSE4 support, I guess there is a way to disable it? Thanks for any inputs.

This line in tensorflow/tensorflow.bzl is responsible for enabling SSE 4.1 instructions in all x86 builds. If you delete that line, the resulting build should work on your machine.

Related

AVX512 not showing on Intel Tensorflow

I have a Windows 11 computer with an 11th Gen Intel Core i7-1185G7, which supports SSE4.1, SSE4.2, AVX, AVX2 and AVX512. The computer has no GPU.
I created a conda environment with Python 3.10, and ran pip install intel-tensorflow. According to the documentation, the command pip install intel-tensorflow-avx512 should only be used on Linux platforms. It mentions that AVX512 is automatically used and enabled on PIP wheels:
All Intel TensorFlow binaries are optimized with oneAPI Deep Neural Network Library (oneDNN), which will use the AVX2 or AVX512F FMA etc CPU instructions automatically in performance-critical operations based on the supported Instruction sets on your machine for both Windows and Linux OS.
However, when I start a new project that uses TensorFlow, the following message is shown:
I tensorflow/core/platform/cpu_feature_guard.cc:193] This TensorFlow binary is optimized with oneAPI Deep Neural Network Library (oneDNN) to use the following CPU instructions in performance-critical operations: AVX AVX2
To enable them in other operations, rebuild TensorFlow with the appropriate compiler flags.
Therefore, I am not sure that TensorFlow is using AVX512 as the default instructions set.
Questions
How can I check that TensorFlow is indeed using AVX512?
If TensorFlow is not using AVX512, how can I force it to? Is it a bug that should be reported to Intel?
Is AVX512 really worth it in comparison with AVX and AVX2 when training a model in TensorFlow on a CPU?
This may not be ideal but you could try WSL and run TF through there using the intel-tensorflow-avx512 package as a test.
It is supposed to be default in the TF windows package as well (no need to use the avx512 pip package), but I’m confirming that now. Will get back to you asap.

build tensorflow from source to use SSE3 and SSE4

Whenever I use tensorflow, it displays the message "The TensorFlow library wasn't compiled to use SSE3 instructions, but these are available on your machine and could speed up CPU computations" and 2 more similar messages.
So I decided to build tensorflow from source to get rid of these messages. I'm using python 3.5 on Debian, and followed the instructions at https://www.tensorflow.org/install/install_sources (CPU only, no GPU).
It asked during the build if the build should be for the machine it's doing the build on, I selected that, it included -march=native in some compiler option.
Everything seemed to work, but when I ran python3 to test the build, it still gives the messages about "The TensorFlow library wasn't compiled to use SSE3 instructions, but these are available ..." etc. How to I make the build use the hardware that it's running on?
There have been similar questions, and most of the answers to them are wrong. They say it's necessary to specify options like "--copt=-msse4.1 --copt=-msse4.2" in the build; it isn't. With the default option "-march=native", the GNU compiler will use SSE4.1 and SSE4.2 instructions if they are available.
The real problem is that if you build tensorflow from source, after installing the default build with pip, pip won't replace the old build with the new build. Everything will seem to work, but your old build remains in place in a directory under ~/.local.
The solution is simply to uninstall the old tensorflow with pip ('pip uninstall tensorflow' or 'pip3 uninstall tensorflow'), and then rebuild from source. If you have already done a build, and wondered why nothing seemed to change, you needn't repeat the build but can just execute the last couple of steps (https://www.tensorflow.org/install/install_sources), namely bazel-bin/tensorflow/tools/pip_package/build_pip_package /tmp/tensorflow_pkg , followed by the pip install.

bazel build Tensorflow from source

I have many big deep learning tasks in python 3.6 ahead and wanted to build tensorflow (CPU only) from source, as my MacBook Pro with Touchbar 13" noted that tensorflow would run faster if it were build with SSE4.1 SSE4.2 AVX AVX2 and FMA support. There are quite a lot questions on StackOverflow and GitHub regarding that topic and I read them all. None of which is addressing why it is not working for me.
I strictly followed the instructions provided by https://www.tensorflow.org/install/install_sources
my configure looks like this
./configure
Please specify the location of python. [Default is /anaconda/bin/python]: /anaconda/python.app/Contents/MacOS/python
Please specify optimization flags to use during compilation when bazel option "--config=opt" is specified [Default is -march=native]:
Do you wish to build TensorFlow with Google Cloud Platform support? [y/N] n
No Google Cloud Platform support will be enabled for TensorFlow
Do you wish to build TensorFlow with Hadoop File System support? [y/N] n
No Hadoop File System support will be enabled for TensorFlow
Do you wish to build TensorFlow with the XLA just-in-time compiler (experimental)? [y/N] n
No XLA JIT support will be enabled for TensorFlow
Do you wish to build TensorFlow with VERBS support? [y/N] n
No VERBS support will be enabled for TensorFlow
Found possible Python library paths:
/anaconda/python.app/Contents/lib/python3.6/site-packages
Please input the desired Python library path to use. Default is [/anaconda/python.app/Contents/lib/python3.6/site-packages]
Using python library path: /anaconda/python.app/Contents/lib/python3.6/site-packages
Do you wish to build TensorFlow with OpenCL support? [y/N] n
No OpenCL support will be enabled for TensorFlow
Do you wish to build TensorFlow with CUDA support? [y/N] n
No CUDA support will be enabled for TensorFlow
INFO: Starting clean (this may take a while). Consider using --async if the clean takes more than several minutes.
Configuration finished
with bazel 0.4.5 I then try to do the build as in the instructions
bazel build --config=opt //tensorflow/tools/pip_package:build_pip_package
This is executed without error but it gives literally hundreds of warnings. I can provide such as an example, but there hardly any snippets that go on without warning.
I appreciate ever help, thank you all very much.
Unfortunately compiler warnings are a fact of life. However, many of these come from external libraries which are pulled into the build. These can be filtered out with the "output_filter" argument to Bazel:
bazel build --config=opt --output_filter='^//tensorflow' //tensorflow/tools/pip_package:build_pip_package
This limits output to warnings generated by TensorFlow code (you can also turn warnings off entirely this way, but that takes all the fun out of compiling). Since the tooling used to build matches what TensorFlow is developed with more closely, there are fewer warnings (I get some about multi-line comment continuations, a bunch of signed/unsigned integer comparisons, and some about variables which "may" be uninitialized).
None of these indicate definite bugs, just patterns of code which are sometimes bug-prone. If the compiler knew something was wrong, it would emit an error instead. Which is a long way of saying there's nothing to worry about.

Bazel builds cause issues when I install TensorFlow using pip

So the documentation mentions that it is better to install from source, then build a pip package. Why is this recommended over doing a direct pip install using the wheel file provided on the downloads page? here
I tried the direct pip install and then runnning some scripts in the inception folder.This results in errors with bazel not finding some of the dependencies. I am guessing this is related to not building tensorflow from source, but I can't figure out why this is the case. Any pointers? Thanks!
Installing from pip is supported, can you provide more details on your os and the specific errors you saw?
The main reason to build from source is simply performance.
Building and installing from source
The default TensorFlow binaries target the broadest range of hardware to make TensorFlow accessible to everyone. If using CPUs for training or inference, it is recommended to compile TensorFlow with all of the optimizations available for the CPU in use. Speedups for training and inference on CPU are documented below in Comparing compiler optimizations.
To install the most optimized version of TensorFlow, build and install from source. If there is a need to build TensorFlow on a platform that has different hardware than the target, then cross-compile with the highest optimizations for the target platform. The following command is an example of using bazel to compile for a specific platform
ref: https://www.tensorflow.org/performance/performance_guide

Distributed compilation for Tensorflow

I am trying to use distcc for speeding-up the Tensorflow compilation. My distcc installations (both on host and client) are working correctly with traditional source packages that use Makefiles for compilation (make -j). But apparently bazel does not use distcc for compiling the Tensorflow sources.
Note that the target platform is a Raspberry Pi 3 running Raspbian Jessy (Ubuntu), thus it is important to offload the compilation on a more powerful machine.
Do you have any experience or suggestions?
Yes. We are using bazel with distcc. You have to write a CROSSTOOL file and then create a wrapper script for gcc that prepends distcc and then forwards the arguments to real gcc.