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Re: [Debian-NYC] debugging network slowness





On Wed, 15 Dec 2010, Daniel Kahn Gillmor <dkg@fifthhorseman.net> wrote:

On 12/15/2010 04:10 PM, steve beltzer wrote:
However, I really would like to be able to start using Debian more and I am
wondering what can be done to get my browser up to speed....  Is it some
sort of mis-communication between Iceweasel and my internet connection?

i understand being frustrated -- it certainly sounds frustrating to me!

to recap:

* we've been using http://nytimes.com as the test site

* during these tests, there has been no detectable shortage of
resources on the local machine (disk I/O well below capacity,
filesystems nowhere near full, lots of free RAM and idle CPU).

* iceweasel on debian takes minutes to load the Times' front page,
though firefox under Win7 takes around 15 seconds.

* wget takes far too long to do something as simple as loading an http
redirect. (15 seconds just to fetch the redirect from
http://nytimes.com/ to http://www.nytimes.com/)

* DNS on its own does not seem to be the problem: directly querying the
local nameservers with dig returns results very quickly (~0.02 to 0.04
seconds), and all three nameservers in resolv.conf are at comparable speeds.

* TCP connections on their own do not seem to be the problem: using
netcat to connect to the times' site and fetch the same 302 redirect is
also trivially quick (less than a tenth of a second)

* The behavior depends on which network you are using (the cafe works
fine; home and eyebeam were problematic).

* You have Atheros ethernet controllers: wired AR8132 (rev c0) and
wireless AR9285 (rev 01)

Is this all correct?  I confess i'm a bit stumped.  I'd be inclined to
try network packet captures next, but i don't really know what i'd be
looking for.

If you can see the problem using wireshark, then likely the
problem will be very easy to see using wireshark.  By "wireshark"
I mean a good packet capture and analysis tool.

oo--JS.



Anyone have any other suggestions?

	--dkg


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