oscar.hellstrom.st :: weblog

After long enough, yet another developer has entered into BSD Land. This one took the way by FreeBSD. Right now I’m mostly benchmarking Erlang applications on FreeBSD, which so far is a bit disappointing, since kpoll is disabled for FreeBSD. Apparently FreeBSD has issues with kqueue and pipes, at least according to the OTP folks. I will try to compile the ERTS with kpoll support anyway, and see what happens. An interesting observation so far is that Ejabberd is spending much more time in kernel-space rather than user-space or this FreeBSD connection. The time spent in kernel-space could probably (?) be shortened with the support for kpoll.

UPDATE:
By hacking the configure script and forcing it to compile with kernel polling support on FreeBSD I noticed really nice performance, until the VM hung for quite some time. It seems that the combination of Erlang, FreeBSD and kqueue indeed have issues.

At the moment I’m running a lot of benchmarks with Tsung. The funny thing with this is that I’ve had more problems getting the client machines to cope with the pressure than the server. I’m running two clients, which are hitting a server, trying to get as many active concurrent connections an possible. Not knowing too much about the inner workings of the Linux TCP/IP stack, I’ve so far run in to ENFILE and EADDRINUSE. The first was kinda expected and is solved by bumping up the allowed file descriptors for the Erlang process. The second however, var rather unexpected, since the clients do not bind to any port. It however turned out that the range of local ports available for non-privileged processes were way to narrow. This magic range is however easily changed with sysctl (net.ipv4.ip_local_port_range) or /proc/sys/net/ipv4/ip_local_port_range.

The server has so far suffered from too few file descriptors, but keeps up rather good :)

OCaml-IXP is now called OCaml-9P…

There was never such a thing as an IXP protocol, it was rather a clever name of another implementation.