cddl/contrib/dtracetoolkit/Examples/weblatency_example.txt

   1 The following is a demonstration of the weblatency.d script.
   2
   3 Here we run weblatency.d while a mozilla browser loads the
   4 http://www.planetsolaris.org website. After the website was loaded, Ctrl-C
   5 was hit to print the following report,
   6
   7    # weblatency.d
   8    Tracing... Hit Ctrl-C to end.
   9    ^C
  10    HOST                                     NUM
  11    static.flickr.com                          1
  12    images.pegasosppc.com                      1
  13    www.planetsolaris.org                      5
  14    blogs.sun.com                              7
  15
  16    HOST                             AVGTIME(ms)
  17    static.flickr.com                         65
  18    blogs.sun.com                            285
  19    images.pegasosppc.com                    491
  20    www.planetsolaris.org                    757
  21
  22    HOST                             MAXTIME(ms)
  23    static.flickr.com                         65
  24    images.pegasosppc.com                    491
  25    blogs.sun.com                            962
  26    www.planetsolaris.org                   3689
  27
  28 This gives us an understanding on which hosts were responsible for the
  29 time endured while loading the website. It turns out that requests to
  30 www.planetsolaris.org were the slowest, with a maximum time of 3.7 seconds
  31 (probably the first request, which incurred a DNS lookup).
  32
  33
  34
  35 The following shows the same google lookup performed on a number of sites,
  36
  37    # weblatency.d
  38    Tracing... Hit Ctrl-C to end.
  39    ^C
  40    HOST                                     NUM
  41    www.google.com.au                          3
  42    www.google.co.uk                           3
  43    www.google.com                             3
  44    www.google.co.nz                           3
  45
  46    HOST                             AVGTIME(ms)
  47    www.google.co.nz                         450
  48    www.google.com.au                        502
  49    www.google.com                           567
  50    www.google.co.uk                         595
  51
  52    HOST                             MAXTIME(ms)
  53    www.google.co.nz                         544
  54    www.google.com.au                        559
  55    www.google.com                           744
  56    www.google.co.uk                         763
  57
  58 From the average time you would guess that I was running this from
  59 New Zealand (the fastest), with times to the other hosts following suit
  60 (Australia, USA, UK). I was actually running this from Australia - it's
  61 interesting that the New Zealand server responded slightly faster.
  62
  63
  64
  65
  66 Now several websites are loaded as a larger demonstration,
  67
  68    # weblatency.d
  69    Tracing... Hit Ctrl-C to end.
  70    ^C
  71    HOST                                     NUM
  72    shop.abc.net.au                            1
  73    static.technorati.com                      1
  74    sunopensolaris.112.2o7.net                 1
  75    www.theage.com.au                          1
  76    ffxcam.smh.com.au                          1
  77    sunglobal.112.2o7.net                      2
  78    embed.technorati.com                       2
  79    technorati.com                             2
  80    fdimages.fairfax.com.au                    4
  81    blogs.sun.com                              5
  82    bugs.opensolaris.org                       7
  83    www.abc.net.au                            34
  84    www.smh.com.au                            51
  85
  86    HOST                             AVGTIME(ms)
  87    ffxcam.smh.com.au                          0
  88    sunglobal.112.2o7.net                      0
  89    www.abc.net.au                            56
  90    www.theage.com.au                         64
  91    shop.abc.net.au                           65
  92    www.smh.com.au                            73
  93    fdimages.fairfax.com.au                   88
  94    blogs.sun.com                            130
  95    bugs.opensolaris.org                     162
  96    static.technorati.com                    350
  97    technorati.com                           352
  98    embed.technorati.com                     632
  99    sunopensolaris.112.2o7.net               900
 100
 101    HOST                             MAXTIME(ms)
 102    ffxcam.smh.com.au                          0
 103    sunglobal.112.2o7.net                      0
 104    www.theage.com.au                         64
 105    shop.abc.net.au                           65
 106    fdimages.fairfax.com.au                  243
 107    www.smh.com.au                           244
 108    blogs.sun.com                            293
 109    www.abc.net.au                           315
 110    static.technorati.com                    350
 111    technorati.com                           356
 112    bugs.opensolaris.org                     560
 113    sunopensolaris.112.2o7.net               900
 114    embed.technorati.com                     973
 115
 116 It's interesting that the most common host (www.smh.com.au, NUM == 51),
 117 responded with a fast AVGTIME (73 ms). The reason for this may be due to
 118 cacheing by my proxy server. Less common hosts such as embed.technorati.com
 119 were quite slow.
 120
 121
 122
 123 The results from weblatency.d are interesting, but they don't point the
 124 finger at one single cause for website latency. The value here is the response
 125 time experienced by the client - which is a combination of many response
 126 times (link speeds, proxy server, DNS server, web server).
 127