Compiling custom version of PHP on CentOS 7 with non-root privilegs

I was trying to test a PHP webapp up on commodity server. Some PHP extensions are not in place while Apache's config files are out of touch due to non-root user privilege.

After a couple of google searches, the closest thing would be how to custom compile PHP engine on web hosting server which fits the scenario of non-root user installation.

First, check out the git source from here:
https://github.com/php/php-src

So far I have been on PHP v7.2.11 and the outcome is satisfied after source compiling.

Second, choose and create a destination directory for new PHP implementation which can be something like:
/home/user/local

Third, steps to compile:

$
$ cd {PHP source directory}
$ make clean
$ ./configure \
  --prefix=/home/user/local \
  --enable-calendar \
  --enable-pcntl \
  --enable-shmop \
  --enable-sockets \
  --enable-mbstring \
  --enable-bcmath \
  --with-gd \
  --with-curl \
  --with-openssl \
  --with-xmlrpc \
  --enable-soap \
  --enable-zip \
  --enable-opcache \
  --with-gd \
  --with-jpeg-dir \
  --with-png-dir \
  --with-mysqli \
  --enable-pcntl \
  --with-pdo-mysql \
  --with-pdo-sqlite \
  --with-pgsql \
  --with-freetype-dir \
  --enable-intl \
  --with-xsl \
  --with-zlib \
  --enable-simplexml \
  --with-sqlite3 \
  --enable-xmlreader \
  --enable-xmlwriter \
  --with-gettext \
  --with-gdbm
$ make
$ make install

Once done, the files will be placed in the directory specified by the flag --prefix.

Please note that a specific PHP target directory is set according to destination directory, i.e., /home/user/local for installation which prevents overwriting default/previous PHP implementation even under non-root privileges.

For fcgid implementation, the following files should be created within the parent directory of targeted PHP app where index.php noramlly stays:

This .htaccess target the wiki webapp whereas first 3 lines may be omitted.

############################ File ".htaccess" (permission:755) ###########################################

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} -f
RewriteRule (api|load)\.php - [L]

Options +Indexes +FollowSymLinks +ExecCGI
AddHandler php-fastcgi72 .php
Action php-fastcgi72 {php_webapp_directory}/php7.fcgi

# DISABLE CACHING

 Header set Cache-Control "no-cache, no-store, must-revalidate"
 Header set Pragma "no-cache"
 Header set Expires 0

############################ End of File ".htaccess"  ###########################################


File "php7.fcgi" must be assigned an execute permission to Apache user/group.
############################ File "php7.fcgi" (permission:775)###########################################

#!/bin/bash

export PHP_INI_SCAN_DIR="/home/user/local/lib/php.d"
export PHP_FCGI_CHILDREN=4
export PHP_FCGI_MAX_REQUESTS=10000
exec /home/user/local/bin/php-cgi -c /home/user/local/lib

############################ End of File "php7.fcgi" ###########################################

I was having trouble to enable opcache for PHP in FCGI mode. However, enabling opcache may not be a good idea for PHP script running in CGI mode (please read here: https://ma.ttias.be/how-to-clear-php-opcache/). Anyway, it's up to your own desire to try improving PHP's performance.

Custom build Tensorflow to support Intel CPU specific instruction set on CentOS 6

Custom build Tensorflow is getting popular as developers have started to push their hardware limit to extreme over the standard build which has no acceleration feature enabled on commodity machines (generally without a decent GPU with compute capability over 3.0).

Different machines have different hardware specifications but most likely the commodity servers have a high chance to equip with powerful multi-core Intel CPU which can go down to the pathway of compiled build against Intel MKL library, e.g. a boost to the deep learning performance via CPU.

CentOS 6.9 comes with older version of GCC compiler which is not helpful in compiling recent version of Tensorflow. So, first thing to do is installing newer version of GCC compiler:

$ yum install 
"http://ftp.scientificlinux.org/linux/scientific/6x/external_products/softwarecollections/yum-conf-softwarecollections-2.0-1.el6.noarch.rpm"
$ yum install devtoolset-6

Here's how Tensorflow CPU version is compiled on CentOS 6.9 platform:

Assuming we are working in CONDA environment:

$ conda activate $CONDA_ENVIRNMENT_NAME
$ scl enable devtoolset-6 bash
$ cd tensorflow
$ bazel build --linkopt=-lrt --config=mkl --copt="-DEIGEN_USE_VML" -c opt //tensorflow/tools/pip_package:build_pip_package
$ bazel-bin/tensorflow/tools/pip_package/build_pip_package ../tensorflow_pkg
$ pip install --upgrade --user ../tensorflow_pkg/<wheel_name.whl>

Funny thing is that Intel has similar instruction which actually recommend installing Tensorflow via CONDA command:

$ conda install tensorflow-mkl

They claimed that warning message like:

Warning: “The TensorFlow library was not compiled to use **** instructions, but these are available on your machine and could speed up CPU computations.”

is actually not harmful at all. As we are installing things along with MKL-DNN library. This warning can be ignored since Intel MKL-DNN library with which the TensorFlow is compiled utilizes the latest Instruction sets available in your processor to perform compute-intensive operations.

It's up to you to trying either easy or hard way to set things up. The performance may not vary too much after all.