this post inspired me to check how much performance can we gain by just upgrading to more recent kernel on the internet-facing proxy servers at work.
i’ve run few benchmarks timing repeated HTTP/1.0 downloads with server located in Szczecin – Poland and one client in Hong Kong [ ~350ms ], another client in Stockholm – Sweden [ ~44ms ]. first test was run with proxy server running debian’s stock kernel 2.6.32, second – with 3.2.0 from backports.
all in all this looks promising and gives reasonable speedup that will be useful in our case [downloads of gzipped xmls each ~5-10kB after compression, occurring every few minutes which is rarely enough not to benefit from persistent http connections].
installation of backports kernel for debian:
echo http://backports.debian.org/debian-backports squeeze-backports main >> /etc/apt/sources.list apt-get update apt-get install -t squeeze-backports linux-image-3.2.0-0.bpo.2-686-pae reboot
methodology: for each size, location and kernel version i’ve run 100 downloads using ab. for each of measurement sessions i’ve rejected 2 slowest downloads.