Saturday, June 28, 2014

#LatencyTipOfTheDay: Median Server Response Time: The number that 99.9999999999% of page views can be worse than.

The math is simple:

The median server response time (MSRT) is measured per request. Pages have many requests.

% of page view that will see a response worse than the MSRT = (1 - (0.5 ^ N)) * 100%.

Where N is the number of [resource requests / objects / HTTP GETs] per page.

Plug in 42, and you get:

(1 - (0.5 ^ 42)) * 100% = 99.999999999977%

Why 42?

Well, beyond that being the obvious answer, it also happens to be the average number of resource requests per page across top sites according to Google's 4 year old stats, collected across billions of web pages at the time [1].  Things have changed since then, and the current number is much higher, but with anything over 50 resource requests per page, which is pretty much everything these days,  both my calculator and excel overflow with too many 9s, and say it's basically 100%. Since I figured 12 9s makes the point well enough, I didn't bother trying a big decimal calculator to compute the infinitesimal chance of someone actually seeing the median or better server response times for a page load in 2014...

[1] Sreeram Ramachandran: "Web metrics: Size and number of resources", May 2010.

Discussion Note:

It's been noted by a few people that this calculation assumes that there is no strong time-correlation of bad or good result. Which is absolutely true. This calculation is valid if every request has an even chance of experiencing a larger-than-median result regardless of what previous results have seen. A strong time correlation would decrease the number of pages that would see worse-than-median results (down to a theoretical 50% in "every response in hour 1 was faster that every result in hour 2" situations). Similarly, a strong time anti-correlation will increase the number of pages that would see a worse-than-median result up to a theoretical 100% (e.g. when every two consecutive response time lie on two opposite sides of the median).

So in reality, if there is some time correlation involved. My number of 9's may be exaggerated. Instead of 99.9999999999% of page views experiencing a response time worse than the median server response time, maybe it's "only" 99.9% of page views that are that really bad. ;-)

Without establishing actual time-correlation or anti-correlation information, the best you can do is act on the basic information at hand. And the only thing we know about the median in most systems (on its own, with no other measured information) 's that the chances of seeing a number above it is 50%.


  1. Hello dear admin,
    you have created an worthwhile article. information you have provided are so intersting. thanks for sharing great stuff. Useful Information on Shrug Ransomware.

  2. replica rolex watches, combining elegant style and cutting-edge technology, a variety of styles of replica rolex pearlmaster watches, the pointer walks between your exclusive taste style.

  3. LifeVoxel.AI has developed a Interactive Streaming and AI Platform for medical imaging using GPU clusters cloud computing. It is a leap in cloud technology platform in medical imaging that encompasses use cases in visualization, AI, image management and workflow. It’s approach is unique that it has been granted 12 International patents. LifeVoxel.AI’s platform is certified for HIPAA compliancy. LifeVoxel’s cloud addresses the Internet limitations of bandwidth, latency and scalability which are pivotal in this respect. The platform was granted an FDA 510K approval for use in diagnostic interpretation of medical images.

    LifeVoxel.AI Interactive Streaming AI Platform RIS PACS server Medical Imaging

  4. Cari Situs Judi Online Terpercaya? Teraman? Banyak Bonusnya?
    Di Sini Tempatnya.

    ZumaQQ, Agen BandarQ, Domino99, Poker Online Terpercaya

    Hanya 4 Tahapan Kemenangan yang MUDAH di ZumaQQ
    Daftar > Depo > Main > Menang!
    Deposit minimal Rp. 20.000,-
    Anda Bisa Menjadi JUTAWAN? Kenapa Tidak?
    Dengan 1 ID sudah bisa bermain 8 Jenis Permainan
    * Agen BandarQ
    * Bandar 66 (New Hot)
    * Bandar Poker
    * Sakong Online
    * Domino99
    * Adu Q
    * Poker
    * Capsa Susun
    Ada Juga Bonus Terhot Se-Indonesia
    Bonus Turnover 0,5%
    Bonus Refferal 10% + 10%

    Yuk gabung bersama kami dan Jadilah Jutawan Berikutnya!
    Website : ZumaQQ
    WA : +85517812404
    Line : ZumaQQ

    blog ZumaQQ

  5. Very efficiently written information. It will be beneficial to anybody who utilizes it, including me. Keep up the good work. For sure i will check out more posts. This site seems to get a good amount of visitors. Click here

  6. Cheat Judi Online bisa memberikan keuntungan dengan cepat dan tentunya bisa membuat anda mendaptakan uang dengan mudah,jika anda berminat maka anda bisa mengunjungi blog dibawah ini.

    Aplikasi Hack Judi Online

    kunjungi juga blog dibawah ini

    info Game Online
    Perlu Menang
    informasi Judi Online
    Prediksi Togel Online

  7. Thanks for provide great informatic and looking beautiful blog, really nice required information & the things i never imagined and i would request, wright more blog and blog post like that for us. Thanks you once agian

    court marriage in delhi ncr
    court marriage in delhi
    court marriage in noida
    court marriage in ghaziabad
    court marriage in gurgaon
    court marriage in faridabad
    court marriage in greater noida
    name change online
    court marriage in chandigarh
    court marriage in bangalore