>>> I did some tests with zfs, and results where appallingly bad, but that was >>> with db size > ram. >>>> >>>> I think the model used by PostgreSQL, as most databases, are very disk >>>> block centric. Using zfs makes it hard to get good performance. But this >>>> was some time ago, maybe things have improved. >> I have some hardware that I ran with last week wherein I was *not* able to >> reproduce any performance difference between ZFS and UFS2. On both UFS2 and >> ZFS I was seeing the same performance when using a a RAID10 / set of >> mirrors. I talked with the Dragonfly folk who originally performed these >> tests and they also saw the same thing: no real performance difference >> between ZFS and UFS. I ran my tests on a host with 16 drive, 10K SAS, 192GB >> RAM. I also created a kernel profiling image and ran the 20 concurrent user >> test under kgprof(1), dtrace, and pmcstat and have the results available: >> >> http://people.freebsd.org/~seanc/pg9.3-fbsd10-profiling/ >> >> There are some investigations that are ongoing as a result of these >> findings. The dfly methodology was observed when generating these results. >> Stay tuned. -sc >> > > I'm not sure that the ZFS vs UFS2 question is at the core of the > performance problem. We're definitely seeing marked slowdowns between > Pg 9.2 and 9.3 on UFS2 (RAID10 + Dell H710p (mfi) raid controller with > 1GB NVRAM)
When the working set fits in RAM (OS + PG), there isn't a performance difference between 9.2 and 9.3. This is a good data point. I will try and reproduce this workload and will run the performance profiling again to see if something else pops up in the profiling. -sc -- Sean Chittenden s...@chittenden.org _______________________________________________ freebsd-performance@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-performance To unsubscribe, send any mail to "freebsd-performance-unsubscr...@freebsd.org"
