Just FYI: I implemented a quick and dirty PoC to see what it'd work like. Not much of a difference on my machine (since postings merging dominates everything else). Interesting problem how to split it up to saturate all of available resources though (CPU and I/O).
https://issues.apache.org/jira/browse/LUCENE-8580 Dawid On Fri, Nov 2, 2018 at 10:17 PM Dawid Weiss <dawid.we...@gmail.com> wrote: > > Thanks for chipping in, Toke. A ~1TB index is impressive. > > Back of the envelope says reading & writing 900GB in 8 hours is > 2*900GB/(8*60*60s) = 64MB/s. I don't remember the interface for our > SSD machine, but even with SATA II this is only ~1/5th of the possible > fairly sequential IO throughput. So for us at least, NVMe drives are > not needed to have single-threaded CPU as bottleneck. > > The mileage will vary depending on the CPU -- if it can merge the data > from multiple files at ones fast enough then it may theoretically > saturate the bandwidth... but I agree we also seem to be CPU bound on > these N-to-1 merges, a regular SSD is enough. > > > And +1 to the issue BTW. > > I agree. Fine-grained granularity here would be a win even in the > regular "merge is a low-priority citizen" case. At least that's what I > tend to think. And if there are spare CPUs, the gain would be > terrific. > > Dawid --------------------------------------------------------------------- To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org For additional commands, e-mail: java-user-h...@lucene.apache.org
