Understanding Linux Load Average – Part 3

Originally posted on The Dutch Prutser's Blog:

In part 1 we performed a series of experiments to explore the relation between CPU utilization and Linux load average. We concluded that the load average is influenced by processes running on or waiting for the CPU. Based on experiments in part 2 we came to the conclusion that processes that are performing disk I/O also influence the load average on a Linux system. In this posting we will do another experiment to find out if the Linux load average is also affected by processes performing network I/O.

Network I/O and load average

To check if a correlation exists between processes performing network I/O and the load average we will start 10 processes generating network I/O on an otherwise idle system and collect various performance related statistics using the sar command. Note: My load-gen script uses the ping command to generate network I/O.

The above output shows that the lo

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Understanding Linux Load Average – Part 3

Understanding Linux Load Average – Part 2

Originally posted on The Dutch Prutser's Blog:

In part 1 we performed a series of experiments to explore the relation between CPU utilization and Linux load average. We came to the conclusion that CPU utilization clearly influences the load average. In part 2 we will continue our experiments and take a look if disk I/O also influences the Linux load average.

Disk I/O and load average

The first experiment is starting 2 processes performing disk I/O on an otherwise idle system to measure the amount I/O issued, the load average and CPU utilization using the sar command. BTW: My load-gen script uses the dd command to generate disk I/O.

The -b command line option given to sar tells it to report disk I/O statistics. The above output tells us that on average 48207 blocks per second were written to disk and almost nothing was read. What effect does this have on the load average?

The run-queue utilization…

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Understanding Linux Load Average – Part 2

Understanding Linux Load Average – Part 1

Ali MEZGANI:

Very nice article on how to detect load average issue

Originally posted on The Dutch Prutser's Blog:

A frequently asked question in my classroom is “What is the meaning of load average and when is it too high?”. This may sound like an easy question, and I really thought it was, but recently I discovered that things aren’t always that easy as they seem. In this first of a three-part post I will explain what the meaning of Linux load average is and how to diagnose load averages that may seem too high.

Obtaining the current load average is very simple by issuing the uptime command:

But what is the meaning of these 3 numbers? Basically load average is the run-queue utilization averaged over the last minute, the last 5 minutes and the last 15 minutes. The run-queue is a list of processes waiting for a resource to become available inside the Linux operating system. The example above indicates that on average there were 10.52 processes waiting…

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Understanding Linux Load Average – Part 1

Serving Flask with nginx

Installing Common Python Tools for Deployment
:
apt-get install -y python python-dev python-distribute python-pip
apt-get install nginx

Installing The Web Application and Its Dependencies
Download and install Flask and uwsgi using pip

pip install virtualenv
mkdir /var/www/ngstones.com && cd /var/www/ngstones.com
virtualenv -p /usr/bin/python venv
source venv/bin/activate
pip install uwsgi
pip install flask

rm /etc/nginx/conf.d/default

vim /etc/nginx/conf.d/ngstones

server {
listen 80;
server_name 10.0.0.2;
charset utf-8;
client_max_body_size 75M;

location / { try_files $uri @ngstones; }
location @ngstones {
include uwsgi_params;
uwsgi_pass unix:/var/www/ngstones.com/demoapp_uwsgi.sock;
}
}

vim /var/www/ngstones.com/demoapp_uwsgi.ini

[uwsgi]
#application's base folder
base = /var/www/ngstones.com

#python module to import
app = hello
module = %(app)

home = %(base)/venv
pythonpath = %(base)

#socket file’s location
socket = /var/www/ngstones.com/%n.sock

#permissions for the socket file
chmod-socket = 666

#the variable that holds a flask application inside the module imported at line #6
callable = app

#location of log files
logto = /var/log/uwsgi/%n.log

vim /var/www/ngstones.com/hello.py
from flask import Flask
app = Flask(__name__)
@app.route(“/”)
def hello():
return “Hello!”
if __name__ == “__main__”:
app.run()

Restart Nginx to load new config file
service nginx restart
cd /var/www/ngstones.com/
uwsgi --ini /var/www/ngstones.com/demoapp_uwsgi.ini

Finally update your DNS and you are good to go!

Serving Flask with nginx

How to Install Docker on Ubuntu 14.04 LTS

Docker is an open-source project that automates the deployment of applications inside software containers, by providing an additional layer of abstraction and automation of operating-system-level virtualization on Linux. Docker uses resource isolation features of the Linux kernel such as cgroups and kernel namespaces to allow independent “containers” to run within a single Linux instance, avoiding the overhead of starting virtual machines.

Here some tips for installing docker on an Ubuntu 14.04 LTS.

Let’s install docker :
apt-get -y install docker.io

Let’s fix link and path :
ln -sf /usr/bin/docker.io /usr/local/bin/docker
sed -i '$acomplete -F _docker docker' /etc/bash_completion.d/docker.io

And finally configure docker to start when the server boot :
update-rc.d docker.io defaults

Of course we search container that contains ubuntu by search token
docker search ubuntu

And we install it
docker pull ubuntu

How to Install Docker on Ubuntu 14.04 LTS

SRE engineer Bookmarks

I’m Linux system engineer and I develop in Python, Bash and Perl. I’m really interested by SRE position for that, I’m applying for SRE Engineer in Google and production Engineer in facebook. and here I share my daily bookmarks :

sre

SRE engineer Bookmarks

Installing smog mongodb viewer

First of all install dependency packages
sudo apt-get update && apt-get install git-core curl build-essential openssl libssl-dev

Install Node.js & NPM
git clone https://github.com/joyent/node.git
cd node

Run git tag to show all available versions
git tag -l

select the latest stable.
git checkout v0.9.9

Run configure and make
./configure
make
sudo make install

Get npm Node package manager using curl
curl https://npmjs.org/install.sh | sudo sh

Install smog using node package manager by running
npm install smog -g

Start smog on background:
smog&

smog will start on default port 8080

Installing smog mongodb viewer