On Wed, Mar 7, 2012 at 10:18 PM, Merlin Moncure <mmoncure@xxxxxxxxx> wrote: > those numbers are stupendous for 8 drive sata. how much shared > buffers do you have? Couple of things to notice: 1) The benchmark can run fully in memory, although not 100% in shared_buffers. 2) These are 100k transaction runs, meaning that probably no checkpointing was going on. 3) Given the amount of memory in the server, with dirty flush settings the OS will do mostly sequential writes. Just ran a quick test. With synchronous_commit=off to simulate a BBU I have no trouble hitting 11k tps on a single SATA disk. Seems to be mostly CPU bound on my workstation (Intel i5 2500K @ 3.9GHz, 16GB memory), dirty writes stay in OS buffers, about 220tps/6MBps of traffic to the xlog's, checkpoint dumps everything to OS cache which is then flushed at about 170MB/s (which probably would do nasty things to latency in real world cases). Unlogged tables are give me about 12k tps which seems to confirm mostly CPU bound. So regardless if the benchmark is a good representation of the target workload or not, it definitely isn't benchmarking the IO system. Ants Aasma -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
