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Performance tests - 1.7, serf and HTTPv2

From: Mark Phippard <markphip_at_gmail.com>
Date: Mon, 28 Mar 2011 16:42:05 -0400

I ran the benchmark test against an http 1.6 and 1.7 server. Details are here:

https://ctf.open.collab.net/sf/wiki/do/viewPage/projects.csvn/wiki/HTTPv2

The results are not encouraging.

* Compared to 1.6, checkout seems to be the biggest problem.

* HTTPv2 seems to help Neon more than it does Serf. In many cases,
both are slower.

* Neon is generally still faster than Serf. In some cases, the HTTPv2
changes seem to have widened the gap.

As I noted on the wiki, I am taking these numbers with a grain of
salt. I think the tests just need to be run more times and by more
people before we draw conclusions. I saw enough outliers during the
tests to say something was going on (perhaps Anti-Virus rearing its
head again?).

There is one issue that I want to raise that I do not think is an
outlier. I was expecting HTTPv2 to yield significant improvements,
and so I stopped the Apache server after each test so I could grab its
logs. I wanted to be able to show how much the HTTP traffic was
reduced. I have not done this yet, but for Serf it looks like the
logs were bigger. The issue I want to raise though is about Serf in
general. Running these benchmarks with Neon yields an Access log of
about 102KB and a Subversion log of about 3KB. Running the benchmarks
with Serf yields an Access log over 12MB and a Subversion log over 5
MB. That concerns me. I am just one user running only a handful of
commands against the server. It looks like a real Subversion server
with just a few dozen active users will be generating logs in excess
of a GB every day. At a minimum we are going to need to document this
in the release notes. I can tell from users@ that most users do not
have log rotation set up. I am concerned about how this might affect
performance of the server and it will certainly leave users vulnerable
to running out of disk space.

Other than looking at some of these logs to see if they show some kind
of problem in Serf, I do not know what else we can do. We know Serf
generates many more requests than Neon when doing checkout/update.
Still, this is alarming when you see the reality of what it means.

-- 
Thanks
Mark Phippard
http://markphip.blogspot.com/
Received on 2011-03-28 22:42:34 CEST

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