[httperf] Modify httperf to do host lookups for each request

Sven Ingebrigt Ulland SvenI.Ulland at iu.hio.no
Thu Apr 6 06:13:25 PDT 2006

On Thu, Apr 06, 2006 at 02:25:05PM +0200, Stan P. van de Burgt wrote:
> I would say that httperf is not the right tool for it as the hits
> will almost always within the TTL.  Maybe we can help out, as we can
> test from 17+ locations in a round robin fashion.

The plan is to perform a series of queries in an environment (virtual
machines first, then a local network), where a few client machines
(three to four) perform requests (including DNS lookups, to simulate
a bunch of independent clients within a domain). Therefore it is
desirable to have many of the hits within the TTL, and then vary the
TTL and observe the impact on total query time. Final results are
expected to show relationships between TTL, RTT (response time), and
requests per second towards a site using DNS-based load balancing.

Simulated WAN-conditions are achieved using the NetEm scheduling
module in linux 2.6. Relevant scheduling variables (latency, variance,
etc) are derived from previous research on the topic.

> We'll need to modify a few things to give you the resolve time, but
> that shouldn't be too hard.

I'm unsure of what you refer to here, is it your in-house watchmouse
monitoring system, http://www.watchmouse.com/en/index.php ? With the
current situation and plan, I don't think it is necessary to involve
third party, but I thank you for the suggestion.

Also, I take the liberty to post this answer to the list, given the
additional information contained within, regarding experiment details.

Sven Ulland

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