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Re: performance loss on real time linux
Michael Ströder wrote:
Pierangelo Masarati wrote:No, I have no idea.
run a simple test using OpenLDAP 2.3.28 running on Linux 2.6.17 with ^^^^^^^^
RTAI, compared to the stock 18.104.22.168 kernel f the distribution
Do you mean stock 2.6.15?
I concur. The point is that to apply RTAI patch we need an official
kernel release (usually the latest, or occasionally the latest-but-one),
but usually we only rebuild it with the RTAI patch, and not without
(there's no need to). So, just to have an idea of how OpenLDAP behaved
with the RT scheduling, I simply ran the same tests with the
distribution's kernel. The distribution was Ubuntu, but I don't
remember the version or any other detail. Only in case of dramatically
slower response I would have checked more carefully those details.
- searching for the same entry, after it's in cache, requires ~0.008s w/
RTAI, and ~0.080s w/o RTAI (ten times longer! It's a slightly different
kernel, but running on exactly the same machine, [..]
Are you sure there haven't been any significant changes to the scheduler
between these two kernel versions anyway? Also distributions most times
ship with a patched kernel. So exact comparison should be done with a
vanilla kernel and the very same kernel with RTAI.