∫ntegrabℓε ∂iﬀerentiαℓs · unorganised notes, code, and writings of random topics

Ridoux and Veitch (2010) Principles of Robust Timing over the Internet (ACM Queue)

May 2, 2010 paper

PC’s clock is an oscillator and HPET (high performance event timer) to count oscillator ticks. The time function is therefore $C(t) = C_0 + p(t) \textrm{HPET}(t)$ where $p(t)$ is the period of clock ticks and HPET is the tick count. Note, $p(t)$ is varying slowly and therefore $C(t)$ is not... [more]

Parallelism by tee in bash

April 26, 2010 blog code

This is what I did in my simulation processing code. [more]

Reservoir Sampling with Uniform Probability

April 26, 2010 blog code

Assume you have a million lines of data in ordered pairs and you want to plot it in GNU Plot. That’s likely to kill your computer. Indeed, plotting a million dots on a graph does not give more information than that plotting a thousand dots. Therefore, how we can sample... [more]

Threading performance checker using GDB

April 13, 2010 blog code

gdb -ex “set pagination 0″ -ex “thread apply all bt” –batch -p ${pid} | awk ‘BEGIN { s = “”; } /Thread/ { print s; s = “”; } /^\#/ { if (s != “” ) { s = s “,” $4} else { s = $4 } } END... [more]

Kandula et al (2009) Flyways To De-Congest Data Center Networks (HotNets)

April 12, 2010 paper

This paper says, if we require a network to be not oversubscribed, the cost is high. For example, if we use fat-tree topology, the networking cost is 2-3x of a tree topology. Using VL2 is even 4-5x. However, it is not necessary to prevent oversubscription because in most of the... [more]