Archive for July, 2014

Debugging Linux: Latency heatmaps

“Odd patterns of I/O latency can be hidden by line graphs and summary statistics, and revealed by histograms and heat maps. In my previous post I showed my Linux iosnoop tool, which can trace block device I/O along with timestamps and latency. This information can be visualized, revealing any odd patterns.”

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Source: http://www.brendangregg.com/blog/2014-07-23/linux-iosnoop-latency-heat-maps.html

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Do you need an alternative shell for your terminal?

“Commands have been a big part of computing ever since the 1970’s.  Their power comes from their simplicity.  Just type a word or two to do what you want.  The time has come to bring this power together with the usability and convenience of modern interfaces.”

“Xiki is open and flexible.  It’s open source, and brings together tools, languages, shells, and text editors, rather than competing with them.  Open formats and languages are the best thing for the tech ecosystem.  HTML and JSON made the web what it is today.  And the web arguably made everything else. 

Xiki strives to be the simplest possible way (and ways) to create interactive interfaces.  This means a text in and text out interface.  Since everything is text, almost nothing is against the rules when you’re creating an interface in Xiki.  Xiki stands for “expanding wiki”, and is inspired by the wiki philosophy of fully editable text, with simple syntaxes (like “>” for a heading, and “-” for a bullet).  Xiki extends wiki ideas to user interface in general.”

Source: https://www.kickstarter.com/projects/xiki/xiki-the-command-revolution

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Knight Rider: a conclusion

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“Knight Rider ist wieder da! Nach Jahren des bangen Wartens zeigt RTL endlich wieder den jungen David Hasselhoff, der mit seinem “Wunderauto” auf große Verbrecherjagd geht. Knight Rider war Kult, Knight Rider ist Kult, und Knight Rider mit Bier ist Oberkult! Angeklebte Armaturen, deren Knöpfe beinahe beliebig in Farbe, Beschriftung und Anordnung variieren, während der Fahrt wechselnde Lenkräder, Stuntfahrer mit krasskranken Clownsfrisuren sowie viele, viele, WIRKLICH viele Logik-, Dreh-, oder sonstwie geartete Fehler laden zur spaßig alkoholgetränkten Analyse ein. Die dümmsten Drehpannen, die peinlichsten Hasselhoff-Anmachen, die unauffälligsten Tarnsack-Autofahrer.”

 

Source: http://www.regelt.org/knightrider/sprittforfun/knightrider.html

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Next step: Holodeck.

“The Infinadeck is the world’s first affordable omnidirectional treadmill that is designed to work both in augmented and virtual reality.  This revolutionary device provides the missing link making it now possible to have a true Holodeck experience. You might say, “Reality just got bigger”.”

Source: http://www.infinadeck.com/

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Nitrous – full IDE in your browser – with Collaboration!

“Nitrous is a backend development platform which helps software developers save time by cutting out the repetitive parts of creating development environments and automating them.

Once you create your first development environment, there are many features which will make development easier.”

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So what you’re getting is:

  • a virtual machine operated for you and set-up with a single click
  • A full-featured IDE in your browser
  • Code-Collaboration by inviting others to edit your project
  • a debugging environment in which you can test-run and work with your code

Here are some screenshots to get you a feel for it:

Source: https://www.nitrous.io/

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Scaling Linux: Perfomance Tools and Measurements

 

If you ever experienced a missmatch between the performance you expected from a server or application running on Linux you probably started to debug your way into it why the applications performance is not on the expected levels.

With Linux being very mature you get an enormous amounts of helpers and interfaces to debug the performance aspects of the operating system and the applications.

Want to see proof? Here – a map of almost all the thingies and interfaces you got:linuxperftools

Thankfully Brendan Gregg put together a page with videos and further links to drill into those interfaces and methods above.

Source: http://www.brendangregg.com/linuxperf.html

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How to get a list of all recent Podcasts on SONOS

I am using an external podcast download tool to stay updated on all podcasts I subscribed to. For this purpose SubSonic is a good choice – actually for a lot more also.

Screen Shot 2014-07-02 at 18.56.52

One of the quirks of the SONOS products is that Podcasts are not really well supported. In fact there is no support at all.

So I wrote a tool that extends the SONOS players with the functionality to “remember” play positions within audiobooks and podcasts. Now what’s left to properly have podcasts supported is a view of the most recently updated podcasts. Wouldn’t it be nice to have a “Folder View” in the SONOS controller of what’s new across all the different podcasts you are subscribed to?

Now here’s the trick:

Use a small script on any RaspberryPi in the house to dynamically create hardlinks to the podcasts files in a “Recently Updated Podcasts” folder.

The script is something like this:

find /where-your-podcasts-are/ -type f -printf ‘%TY-%Tm-%Td %TT %p\n’ | sort | tail -n 25 | cut -c 32- | sed -e “s/^/ln \”/” -e “s/$/\”/” -e “s/$/ \”\/recentPodcasts\/\”/” | sh

This short line will go through all folders and subfolders in /where-your-podcasts-are/ and then create Hardlinks in /recentPodcasts to the most recent 25 files.

That way, and when /recentPodcasts/ is made accessible to your SONOS controllers, you’ll have something like this:

Screen Shot 2014-07-02 at 19.17.24

Source 1: http://www.subsonic.org
Source 2: play position bookmarker

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