Subject: Re: MP safe syscall changes
To: Andrew Doran <>
From: Perry E. Metzger <>
List: tech-smp
Date: 02/05/2007 18:29:54
Andrew Doran <> writes:
> I just made a bunch more syscalls MP safe on the newlock2 branch, and ran a
> quick test on this machine: 4 x 700MHz P-III Xeon, 1MB L2 cache per CPU, 2GB
> RAM. Cleaning out a clean source tree with make -j16 cleandir:

I'm happy (and surprised) that there is a speedup here. Consider that
this is not an embarrassingly parallel task: removing lots of files is
ultimately bottlenecked on the disk and not something where we would
expect much parallel speedup.

>                 real            system
> MP              -9%             -14%
> UP              -0.5%           +3.5%

I would be quite interested in seeing figures for building the world
in both the current MP and newlock2 MP cases. *That* might have some
interesting opportunities for parallelism on a machine with 2G of
ram. Do knock up the number of vnodes to around 2^17 or 2^18th before
starting, though, or you might end up a bit i/o bound with that much