Hi,

Recently I came across this site: http://bulk.fefe.de/scalability/

The author ran a number of microbenchmarks on a then-current Linux and BSD
systems to get an idea of the scalability (or breakdown) of a number of
common and uncommon paths. I just ran the tests on a DragonFly 2.9 (kernel
of 03/04/2011, compiled with gcc 4.4, world of 3/2) 1.5 GHz P4 (willamette)
with 512 MB of RAM. I don't have any comments on the tests themselves, here
are just graphs of the results.

-> The first test from the set I ran was the bind benchmark; this just calls
bind to port 0 on a number of sockets.
http://m-net.arbornet.org/~sv5679/bind4-dfly-03042011.png
(using the same scale as the graph on the original page)

-> The fork benchmark; creates a pipe, forks a number of child processes,
wait for each to write a byte into that pipe; aggregates time between fork
and receiving the byte.
http://m-net.arbornet.org/~sv5679/fork-dfly-03042011.png
(larger vertical scale than fefe.de)

-> The static fork benchmark; same as above, but with a statically linked
process.
http://m-net.arbornet.org/~sv5679/fork-vs-forks-dfly-03042011.png
(larger vertical scale than fefe.de)

-> The mmap benchmark:
http://m-net.arbornet.org/~sv5679/mmap-dfly-03042011.png
(very similar scale)

-> the mmap benchmark part 2 (touching the pages);
http://m-net.arbornet.org/~sv5679/mmap1-dfly-03042011.png
(same scale)

-> Fork cleanup benchmark (in the comments):
http://m-net.arbornet.org/~sv5679/fork-cleanup-latency2-dfly-03042011.png
(same scale)

Overall, our graphs look very similar to the FreeBSD systems tested there
(shapewise; the hardware & values are different and not directly
comparable); our fork() curve is closer to FreeBSD 4's than FreeBSD 5's,
(see http://bulk.fefe.de/scalability/freebsd/fork-freebsd-current.png and
http://m-net.arbornet.org/~sv5679/fork-dfly-03042011.png).

Just thought that these'd be interesting. Take them with a grain of pepper;
they are microbenchmarks and are measuring things about very specific code
paths.

-- vs

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