Sourajit Basak [sourajit.ba...@gmail.com]: > Does more processors with less cores or less processors with more cores > i.e. which of 4P2C or 2P4C has best cost per query ?
I have not tested that, so everything I say is (somewhat qualified) guesswork. Assuming a NUMA architecture, my guess is that 2P4C would be superior to 4P2C. Solr utilizes both disk caching and explicit caching on the JVM heap making memory access quite heavy; the less processors, the higher the chance that the memory will be controlled by the processor running the given search thread. I am by no means a NUMA expert, but it seems that requests for memory controlled by another processor takes about twice as long as local memory. Our machine is a NUMA dual processor and if I can find the time, I would love to perform some tests on how that part influences query time. If would be interesting to lock usage to 2 cores on each processor vs. 4 cores on the same processor. The tricky part is to ensure that RAM is fully controlled by the single processor in the second test, including the disk cache. Regards, Toke Eskildsen
