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From: Ron Brightwell (rbbrigh_at_[hidden])
Date: 2006-02-09 16:05:07


> [...]
>
> >From an adoption perspective, though, the ability to shine in
> micro-benchmarks is important, even if it means using an ad-hoc tuning.
> There is some justification for it after all. There are small clusters
> out there (many more than big ones, in fact) so taking maximum advantage
> of a small scale is relevant.

I'm obliged to point out that you jumped to a conclusion -- possibly true
in some cases, but not always.

You assumed that a performance increase for a two-node micro-benchmark
would result in an application performance increase for a small cluster.
Using RDMA for short messages is the default on small clusters *because*
of the two-node micro-benchmark, not because the cluster is small.

I've seen plenty of cases where doing the scalable thing, rather than the
optimized for micro-benchmarks thing, leads to increases in application
performance even at a small scale.

-Ron