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  • fala13 23:16 on 05/11/2014 Permalink | Reply
    Tags: conference, , Nokia, Scott Meyers, Venkat Subramaniam   

    Nokia image win 


    Scott Meyers presents false sharing (sub-case of cache thrashing)

    Code::dive conference successfully took place today in Wrocław. Surprisingly it was organized by my company – Nokia. Surprisingly, because previous efforts to represent ourselves locally where not as glamorous to say the least and some plainly failed to get off the ground.

    Today’s event was pretty great and it looked like money. I do think it should look this way and it finally made visible that Nokia focuses on developers and commits to spend cash on them. If we want to be perceived to be in the same league as Google and Microsoft we need to show off big at times like today.

    Scott Meyers certainly was the star of the event and his talk on cashes was great and fun, however thanks to Venkat Subramaniam I got to see a programming stand-up comedy show for the first time. His light and hilarious talks really made my day. Hopefully you can see his functional programming talk here.

    Do not hesitate if you have a chance to attend next year!

    P.S. yes, I know about PGO for a long time now. I will try it out when I’m done with memory leak detection improvements that are all the rage these days.

  • fala13 21:50 on 27/03/2014 Permalink | Reply
    Tags: cloud, conference,   

    War in the skies and some other rumors from the performance engineers world 

    I’ve just returned from ICPE2014 conference taking place in Dublin. Apart from lots of cloud, VM and power scaling related talks there were many that applied to what I do – building and maintaining SW performance models, creating and working with load tests and lower level stuff like niceness in Linux and CPU cache.

    Some fancy facts and rumors I’ve picked up:

    • Amazon estimates that 100ms in latency on their pages costs 1% in its sales.
    • Google says 0.5s lag results in 20% drop in their traffic.
    • Bank of America had 2 performance engineers earning 1 million $ a year. New manager came to cut costs and fired them. After a year the performance dropped so badly that Bank had to buy additional servers for 15 million $. Unfortunately after another year it was not enough to support the load and other expenses (and sacking of the said manager) had to follow.
    • One mentioned bottleneck bugs during conference was bad implementation of visitor pattern (we also had issues with those).
    • Lots of attention given to optimal cache utilization (e.g. use structure of arrays rather than arrays of structures).
    • In 2012 already data centers used power equivalent to that of 30 nuclear power plants.
    • Dark shipping – a technique to test your new SW by transparently routing request in parallel to your old and new SW. Customer only gets results from old SW but you observe how new SW works and if it provides same output.
    • New CPU accelerator Intel Xeon Phi (60 CPU ~= 1 TFLOP) still slower than NVIDIA CUDA Kepler GPU due to different cache memory structure – you really need to put a lot of effort in parallelizing your program (like manual vectorization) to utilize such accelerators.

    All in all it seems it pays off to be a cloud expert those days as there is a kind of arms race and cloud war going on with Google aggresively dropping its prices. During the conference there was a lot of talks on scaling of the cloud and its power efficiency so there is definitely something in the air ;).

    Some photos from my stay in Dublin:

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