Updates from fala13 Toggle Comment Threads | Keyboard Shortcuts

  • fala13 15:30 on 19/06/2018 Permalink | Reply

    Watching stream of cloudXchange, conference covering Cloud and some performance topics

    website: https://www.cmg.org/cloudxchange/

  • fala13 13:56 on 17/06/2018 Permalink | Reply
    Tags: , Codingame, , , ,   

    CODE OF KUTULU @ Codingame 

    Why play games when you can write bots to play them? Join me at: https://www.codingame.com/contests/code-of-kutulu

    Once again I’m taking part in CodinGame online contest, this time in Lovecraftian theme ending on June 25. You implement a bot that is supposed to play in game run on Codingame site against other bots. The game is about explorers trying to survive the longest in a dungeon before losing their sanity.

    I already did get to silver leagues in other games like Ghost in the Cell (while refreshing my C++), Code Royale (Dota-like game, worked on my Python3 skills). In Code Royale I played with strategy pattern, so that I could easily change the behavior of bot and started using this lisp-like predicate construct to help me pipe a lot of conditions easily and read-ably:

    def dt(cond, l, r):
        x = cond is True
        print(str(x), file=sys.stderr)
        if x:
            return l
            return r

    This time I also want to setup my deck to be able to run games offline for faster feedback and potentially play with some better algorithms.

    Best players create simulations of the game, often re-implementing it for performance reasons. Being able to simulate the progress of the game they apply Mini-maxes, Genetic Algorithms, Neural Networks and other fancy things to select the best moves. This is in line with what Elon Musks OpenAI owning Dota2 single-player is about:

    edit: nice deep dive into properly approaching this kind of contests: https://github.com/Manwe56/competitive-programming/blob/master/docs/advices.pdf
    edit2: This post comes down to two songs by same guy:

  • fala13 22:21 on 25/02/2015 Permalink | Reply

    I’d Love To Change The World 

    It’s all a bit gloomy with my wife moving temporarily to Germany to pursue her doctorate. On top of that I’ve recently changed departments (after growing roots in the last one for 6 years) and I am now starting almost from scratch. So I went on to reflect for a moment and tried to put my life in a perspective. That led to some weird findings.

    First I tried to calculate my remaining life span. DeathClock is a straightforward site just for that (and here is mine 43 years countdown).

    Surprisingly, few clicks away were the Worldometers, a set of global counters based on heavy government and organizations data. Just few looks lets you spot that:

    • Twice many people are born as die?!
    • Twice many people are fat as starving.
    • 5% of worlds healthcare money goes to cure obesity in USA alone.
    • Demand for TV sets is 80 times lower than for computers.
    • 1/2 of people in the world use Internet.
    • Poeple are tweeting 226 times more frequently than blogging.
    • Gasoline will run out in 39 years (that means I will live to see it!).
    • Luckily natural gas will be around for 163 years. My car runs on it already.
    • We still have coal for 413 years.
    • The number of people with HIV/AIDS is almost the same as the total number of people in Poland.

    The site authors have other cool things going as well: Internet stats and Money meters.

    Those sites are important, because they show you the real data and let you do the thinking. If you watched the Nightcrawler recently, you get the idea how news do everything but that.

    In the end I got to some other site that promised to exactly project my remaining lifespan based on detailed input options. I meddled with them for 5 minutes, pressed “Calculate” and the site said:
    Date of my death
    (NaN means Not-a-Number, error in computation)

  • fala13 23:16 on 05/11/2014 Permalink | Reply
    Tags: , , 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 03:52 on 06/07/2014 Permalink | Reply
    Tags: , ,   

    24 hours in 32 seconds 

    At 1 AM yesterday I got on a bus from Wrocław to Warsaw. I got back at 1 AM today and here is a short movie compilation of what it was about:


    Your browser does not support the video tag.

    (embedding videos from OneDrive in WordPress seems broken)

  • fala13 17:59 on 02/06/2014 Permalink | Reply
    Tags: , compilation, gcc,   

    Bad performance after switching to C++11?! 

    Recently tool chain in my company (which is called Nokia now – awesome, right?) was update from GCC 4.2 to GCC 4.7. Everybody in my project was very excited – our software will be faster thanks to the move concept and just from standing next to the new compiler! And developers will be able to write lambdas that no one else will be able to decode!

    When first performance test results came in I was puzzled – improvement was expected and we got 5-10% performance decrease? I had to ask my overly enthusiastic developers to wait with enriching their code with new shenanigans and I’ve put my detective hat on.
    I’ve discovered that the new compiler is not to blame, only adding -std=c++11 makes the difference and shortly after Stackoverflow came with help: http://stackoverflow.com/questions/20977741/stdvector-performance-regression-when-enabling-c11
    Sufficient to say, default settings of GCC don’t trigger proper inlining of container methods of the STL’s C++11 version. When we increased the -finline-limit the performance got back to level without the -std=c++11 flag. But not a bit higher.

    Background: Our project does lot of message handling, uses STL quite heavily and is around 1 milion LOC. We get best results with -O2, yes, even better than with -O3. I have tested various flag combinations and nothing matches regular -O2. But that is for our application and our fast path use pattern. For yours you should always test, test and test for yourself (and investigate!).

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

    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:

  • fala13 18:07 on 08/02/2014 Permalink | Reply
    Tags: health, snowboard   

    Archers of Troy 


    I fully ruptured Achilles tendon while falling badly doing 180 jump on a snowboard. I was lucky to be taken to a great clinic in Sankt Moritz for the surgery. Apart from the food being amazing (check this out), the attitude of people and doctors was supportive and caring. Can you imagine a doctor greeting you, reaching out his hand to you, presenting himself and asking your name? I couldn’t until now. It is really easier to get better and stay positive when people taking care of you are so nice and friendly.

    After 1.5 month I’m able to slowly walk on my own. Thanks to doctors in Switzerland and effort from amazing physiotherapists here in Wrocław the leg is very slowly regaining its strength and range of motion. Contrary to popular opinion I came to believe that Achilles tendon rupture is not as bad as breaking a leg. For sure the recovery is quicker and it is easier to avoid muscular dystrophy. Here are some lessons learned regarding health that I have found out the hard way (free for you to take away!):

    • Being able to carry your tee around is one of the greatest underestimated things we experience daily – with crutches you can’t take things with you. Wearing backpack helps but still doesn’t allow you to enjoy tee outside of kitchen.
    • Follow your friends advice when you are in bad shape – after the injury I wanted to go back to Poland for surgery but friends convinced me to try to get the surgery done on place. From what I know now it would be likely for me to get the leg fully covered in plaster and I wouldn’t even have seen a physiotherapist by now. Also supposedly the stitching is neglected and done very poorly in Poland resulting in ugly scars for the rest of your life.
    • Human is able to accustom to pain – the injury hurt so bad that I only was really troubled by pain when I fell by accident on that leg some time later. Doing anti-thrombosis shots daily in my belly for over a month also made me more a bystander to my pain and not the receiver.
    • Walking with crutches sucks – it really does. First two weeks my palms and hands were aching and swollen.
    • Strange observation: while walking with crutches in a not crowded bus/tramway people respond to you very kindly and try to help you. When it gets crowded and you really would appreciate if somebody would empty a seat for you or move away then suddenly – you are invisible. Some kind of crowd-behavior. It does confirm that you are more likely to receive help from an individual than from a group of people.
    • Having health care does not guarantee you a sensible treatment. You need to fight for your health, do research and visit multiple doctors when in doubt. I visited four different doctors in Poland for prescriptions and check-ups:
      1. First doctor I visited after surgery said that I shouldn’t be starting physiotherapy for a month and when I expressed my doubts he gave me a lecture on how in the USA rupture of Achilles tendon is operated only when the person is a sportsman or wealthy as normal people don’t need full range of motion of their leg anyway…
      2. Two weeks after that another doctor was angry at me that I didn’t start physiotherapy yet. So I started it next day and I’m very happy that I did.
      3. Third doctor said that he was not the one who operated so he can’t help me or judge the state of my leg. (Like I could fly back to Switzerland for a check-up).
      4. Fourth doctor was nice but also didn’t pay too much attention to the leg itself.

    And that brings us to the major life knowledge to be taken from this whole affair:

    For skiing and snowboarding go to countries with premium health care! – the European health insurance guarantees that you will get service on the level of the country you are currently in.

    To sum up thanks to being cured in Switzerland I got:

    • super-friendly people taking care of me.
    • restaurant-level food, selectable from menu day earlier – deserts, chocolates, etc.
    • crutches with ice grip attachments.
    • high quality adjustable orthosis for the leg instead of plaster.
    • perfectly straight, well stitched scar.
    • Chance to talk to 83-year old American skier who lives in Greece and was laying in next bed.

    PS. while researching Achilles rupture I stumbled upon this great image showing the Heel of Achilles.

  • fala13 10:44 on 03/11/2013 Permalink | Reply
    Tags: agile, , , Neil Gunther, ,   

    Obama's health website is a performance failure 

    One of the biggest US computer software projects had just gone bust on our eyes. The site responsiveness was so low that ‘virtual waiting rooms’ had to be implemented. It’s fun to watch, especially if you have been struggling with similar quality, management and performance issues in your own career.

    Check out the summary of articles on Neil Gunther’s (performance engineering guru) blog: http://perfdynamics.blogspot.com/2013/10/what-happened-at-healthcaregov.html

    If you think this is TLDR (too long, didn’t read) then let me offer you a short wrap up (should sound familiar if you worked in any software business):

    • Requirements were supplied late and changed during implementation
    • Unrealistic deadlines
    • Agile methodologies were used by companies
    • After the initial failure tons of people and consultants where thrown in to ‘fix’ it (including the infamous Booz Allen Hamilton – Edward Snowden employers)
    • President had to publicly apologize for the broken web site

    If you are interested how it looks from software infrastructure perspective take a look at this nice graphic summing it up: http://www.thedoctorweighsin.com/healthcare-dot-gov-how-does-it-work-infographic/

    And to finish with the NYT citation: “Indeed, according to the research firm the Standish Group, 94 percent of large federal information technology projects over the past 10 years were unsuccessful — more than half were delayed, over budget, or didn’t meet user expectations, and 41.4 percent failed completely.”

  • fala13 11:10 on 20/10/2013 Permalink | Reply
    Tags: , ,   

    Wh40k autumn tournament spree summary 

    Wraithlord and the beasts

    Wraithlord in deployment

    After the tournament in Zielona góra I went on a tournament spree – first a Master class tournament in Kraków called Arena 2k13 and then Championships of Łódź. For the master class tournament you have to have your full army painted so two weeks of my life went by on being glued to the aerograph which settled on desk for good.

    The effort payed of and I was able to win 4 out of 5 battles in Kraków and finish 22nd / 64 players. The tournament was held in primary school and we stayed there for the night. Playing four hands piano in music class past midnight – priceless.

    The next tournament in Łódź didn’t turn out for me that well. I lost all 3 battles and was next to last. So lame.

    Now I need to skip some tournaments as my personal life kicked in. Having painted army feels good and the weeks spent on that were well worth it.

    More snaps:

Compose new post
Next post/Next comment
Previous post/Previous comment
Show/Hide comments
Go to top
Go to login
Show/Hide help
shift + esc