I think it would improve the functionality in wtperf if we could specify groups of threads that carry out certain operations.

The way I'm seeing the configuration API is:

threads=[(count=1,updates=1),(count=1,reads=1)]

Would mean have two threads. one doing updates, the other doing reads.

threads=[(count=5,updates=3,reads=1)]

Would mean have five threads, all of them doing 75% updates and 25% reads.

I don't really mind if the operation configuration is based on a ratio (as above), or a percentage (as in the current run_mix_xxx configurations). Though I think we should pick one or the other.