> Making compaction parallel isn't a priority because the problem is > almost always the opposite: how do we spread it out over a longer > period of time instead of sharp spikes of activity that hurt > read/write latency. I'd be very surprised if latency would be > acceptable if you did have parallel compaction. In other words, your > real problem is you need more capacity for your workload.
Do you expect this to be true even with the I/O situation improved (i.e., under conditions where the additional I/O is not a problem)? It seems counter-intuitive to me that single-core compaction would make a huge impact on latency when compaction is CPU bound on a 8+ core system under moderate load (even taking into account cache coherency/NUMA etc). -- / Peter Schuller
