I'll just add that CPU usage hovered around 50% during these tests. On Jul 19, 2010, at 3:51 PM, David Schoonover wrote:
> Sorry, mixed signals in my response. I was partially replying to suggestions > that we were limited by the box's NIC or DC's bandwidth (which is gigabit, no > dice there). I also ran the tests with -t50 on multiple tester machines in > the cloud with no change in performance; I've now rerun those tests on > dedicated hardware. > > > reads/sec @ > nodes one client two clients > 1 53k 73k > 2 37k 50k > 4 37k 50k > > > Notes: > - All notes from the previous dataset apply here. > - All clients were reading with 50 processes. > - Test clients were not co-located with the databases or each other. > - All machines are in the same DC. > - Servers showed about 20MB/sec in network i/o for the multi-node clusters, > which is well under the max for gigabit. > - Latency was about 2.5ms/req. > > > At this point, we'd really appreciate it if anyone else could attempt to > replicate our results. Ultimately, our goal is to see an increase in > throughput given an increase in cluster size. > > -- > David Schoonover > > On Jul 19, 2010, at 2:25 PM, Stu Hood wrote: > >> If you put 25 processes on each of the 2 machines, all you are testing is >> how fast 50 processes can hit Cassandra... the point of using more machines >> is that you can use more processes. >> >> Presumably, for a single machine, there is some limit (K) to the number of >> processes that will give you additional gains: above that point, you should >> use more machines, each running K processes. >> >
