DTrace Mozilla - DNS timing mystery solved :)

Well - solving many problems is often best done by not trying to solve them at all ;) Left the mystery of my 10 sec DNS lookups after scratching my head over it for a day or so.

I was a little suspicious that my home setup with a router connected to my dsl modem might have been causing problems, so I wanted to try the probes out in work. Headed in today and fired things up but got zippo hits for my dnslookup-start/done probes. Himm what was going on? Well added in an aggregate into the dnslookup-init probe to see what hosts it was asking for and turns out to be hitting "webcache.uk.sun.com", our internal web cache for all it's lookups :)

Now getting out and around our webcache can require a little magic, but thanks to Daren Kenny I got a direct connection out bypassing the webcache server, thanks Darren! Now when I fired up the browser and did a little surfing to finance.yahoo.com with the browserspy script running I see the following:

DTrace Stats for: http://finance.yahoo.com

PROBE STATS:

TYPE TOTAL COUNT
DNS_REQ Network Requests - Done 14
DNS_REQ Network Requests - Started 14
DNS_LOAD Lookups - Network and Cache 23

TYPE TOTAL COUNT
URI Network Requests - Done 7
URI Network Requests - Started 8
IMAGE_REQ Network Requests - Done 37
IMAGE_REQ Network Requests - Started 37
IMAGE_LOAD Image Loads - Network and Cache 70

Browser DNS lookup requests,

PID UID STATUS COUNT AVG(msec) SUM(msec) IP HOST
1973 65535 1 1 0 0 72.14.203.91 sb.google.com
1973 65535 1 1 0 0 209.62.176.152 ad.doubleclick.net
1973 65535 1 1 293 293 69.8.201.107 ads.yimg.com
1973 65535 1 1 318 318 69.8.201.80 us.i1.yimg.com
1973 65535 1 1 325 325 69.8.201.75 us.news2.yimg.com
1973 65535 1 1 360 360 68.142.196.87 finance.yahoo.com
1973 65535 1 1 453 453 68.142.213.132 us.bc.yahoo.com
1973 65535 1 1 455 455 68.142.196.15 ichart.finance.yahoo.com
1973 65535 1 1 568 568 209.62.178.57 ad.uk.doubleclick.net
1973 65535 1 1 602 602 68.142.213.142 l.yimg.com
1973 65535 1 1 776 776 209.225.0.101 servedby.advertising.com
1973 65535 1 1 850 850 216.73.84.103 m.uk.2mdn.net
1973 65535 1 1 4223 4223 69.8.201.75 us.js2.yimg.com
1973 65535 1 1 5117 5117 216.252.106.98 streamerapi.finance.yahoo.com
:
:

Happy days :) It was a configuration issue, we are now seeing a much happier spread of dnslookup times. Time for me to see if I can bypass my router at home and use the dns server that the modem is using directly, should certainly make my browsing a lot faster!!

[Update]: Checked it at home changed my /etc/resolv.conf to use the netopia dsl's nameserver and all is well with the world. Now no excuse to go and get a cup of coffee, it's all so dam fast ;) Interesting that it's a lot faster at home than at work, similar times of day as well, curious indeed, must point out to our sys admins.

DTrace Stats for: http://finance.yahoo.com from Home

PROBE STATS:

TYPE TOTAL COUNT
DNS_REQ Network Requests - Done 11
DNS_REQ Network Requests - Started 11
DNS_LOAD Lookups - Network and Cache 20

TYPE TOTAL COUNT
URI Network Requests - Done 1
URI Network Requests - Started 1
IMAGE_REQ Network Requests - Done 40
IMAGE_REQ Network Requests - Started 40
IMAGE_LOAD Image Loads - Network and Cache 71

Browser DNS lookup requests,

PID UID STATUS COUNT AVG(msec) SUM(msec) IP HOST
3237 65535 1 1 30 30 217.146.179.200 us.bc.yahoo.com
3237 65535 1 1 31 31 159.134.196.102 us.js2.yimg.com
3237 65535 1 1 43 43 159.134.196.103 l.yimg.com
3237 65535 1 1 46 46 159.134.196.118 us.i1.yimg.com
3237 65535 1 1 57 57 206.190.56.229 finance.yahoo.com
3237 65535 1 1 64 64 159.134.196.117 speed.pointroll.com
3237 65535 1 1 80 80 216.73.87.74 ad.doubleclick.net
3237 65535 1 1 98 98 159.134.196.102 us.news2.yimg.com
3237 65535 1 1 128 128 159.134.196.118 ads.yimg.com
3237 65535 1 1 161 161 72.32.153.176 ads.pointroll.com
3237 65535 1 1 652 652 206.190.56.234 ichart.finance.yahoo.com

Well the probes have their uses after all, as my friend always says when we are out hiking, trust the compass, even if you are 100% sure it can't be right, it is ;) Unless of course you are standing on top of some lodestone, but that's another issue entirely!

 


 

Comments:

Post a Comment:
Comments are closed for this entry.
About

jmr

Search

Top Tags
Categories
Archives
« April 2014
MonTueWedThuFriSatSun
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
    
       
Today