Category: Uncategorized

ffmpeg: Part I

Brief Software to convert video to format A to format B Installing on Ubuntu 14.10 Courtesy to this ffmpeg install tip $sudo  add-apt-repository ppa:jon-severinsson/ffmpeg $ sudo apt-get install ffmpeg Quick facts about ffmpeg Written in C Open source

Google App Engine: Data store with async calls

Google Data Store provides single core CPU  (F class) for applications. Hence heavily multi-threaded applications can’t scale enough DataStoreprovidesasync calls for DB access. It has: Async queries Async transactions Async read/writes Documentation is good but lacks clarity on usage and benefits on async calls. It says that async queries can run in parallel after immediately returning a temporary result object.…

File system in userspace (FUSE) on Linux : C implementation

BBFS is a good starting point to develop a file system in C Application should keep in mind file offset before issuing a request. A write should be followed with a seek to offset zero, before issuing read. FUSE 2.7 reads 8K data by default, in two 4K chunks Read happens in last 4K and the first 4K data block…

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Free, open source wiki Single HTML file, opens in all standard browsers Supports WikiText Keep your wiki on dropbox and then you have a everywhere available wiki Works best with Firefox

Linux KSM: Kernel Samepage Merging / Kernel Shared Memory

Kernel 2.6+ have ksm feature that allows kernel to dedup pages across processes. This could lead to decent memory saving especially on a host OS in a virtual machines environment. Ubuntu 12.04 kernel has KSM support, but it is not enabled. $ cat /etc/issue Ubuntu 12.04.4 LTS \n \l $ grep KSM /boot/config-`uname -r` CONFIG_KSM=y $ ll /sys/kernel/mm/ksm/ total 0…

2013 in review

The WordPress.com stats helper monkeys prepared a 2013 annual report for this blog. Here’s an excerpt: The concert hall at the Sydney Opera House holds 2,700 people. This blog was viewed about 19,000 times in 2013. If it were a concert at Sydney Opera House, it would take about 7 sold-out performances for that many people to see it. Click…

2013: wrapping up with reflections

This year has been an exciting year with variety of learning on technologies. A notable list of subjects and achievements is following: No-SQL Object storage MongoDB (internals) Openstack Swift (internals) Speaking at PyCon, Auckland, New Zealand Reflecting on the time of this year, I have learned following: Work plays a major role in man’s happiness. Choose your workplace well. It…

Openstack Swift: Introduction for Developers (Part II)

Object server Source File Swift object serve is the storage server for objects. Each object is stored as files on native file-system. Object server keeps object with its metadata on a plain file. PUT, GET and HEAD are useful to look at. Running benchmarking tools swift-bench ssbench cosbench swift-bench is the easiest to use. You need to get sample config…