Date: Wed, 21 May 2014 19:05:01 +0100 From: Matthew Seaman <matthew@FreeBSD.org> To: freebsd-performance@freebsd.org Subject: Re: FreeBSD 10 and PostgreSQL 9.3 scalability issues Message-ID: <537CEACD.8090701@FreeBSD.org> In-Reply-To: <sig.02184fa928.F0529F5B-72EC-4E68-A4BD-75276C70AC1C@chittenden.org> References: <5327B9B7.3050103@gmail.com> <2610F490C952470C9D15999550F67068@multiplay.co.uk> <532A192A.1070509@gmail.com> <assp.0155c70d29.23ED6415-945D-4DF5-90DD-2F2CD7E198AF@chittenden.org> <f4ead73a-fae2-4eac-8499-3cf630eb3d31@googlegroups.com> <CAJ-VmomVOWFb7X5s-amRX7QFzbmT6Kt6bB9gaPVv2_hGx1OS5g@mail.gmail.com> <572540F9-13E4-4BA9-88AE-5F47FB19450A@pingpong.net> <CAJKO3mUTwgiQenSLYfOxHrZxuPQ9kvUPC44MrbLjvpLE=toZQA@mail.gmail.com> <1BC3D447-2044-4AB8-B183-B83957BC9112@pingpong.net> <CAJKO3mX5KA8HZ5tQGTyOgfKbS6HvUvYH-gvzeewTkh3nWz=NRg@mail.gmail.com> <1473AF7C-B190-4CD4-B611-BA4090A081CB@pingpong.net> <sig.02184fa928.F0529F5B-72EC-4E68-A4BD-75276C70AC1C@chittenden.org>
next in thread | previous in thread | raw e-mail | index | archive | help
[-- Attachment #1 --] On 21/05/2014 18:17, Sean Chittenden wrote: >> 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) In our case the DB size is significantly bigger than RAM, and we also run with a large (3GB) work mem, which seems to exacerbate the slow-down effect. Cheers, Matthew -- Dr Matthew J Seaman MA, D.Phil. PGP: http://www.infracaninophile.co.uk/pgpkey [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.20 (Darwin) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQJ8BAEBCgBmBQJTfOrOXxSAAAAAAC4AKGlzc3Vlci1mcHJAbm90YXRpb25zLm9w ZW5wZ3AuZmlmdGhob3JzZW1hbi5uZXQ2NTNBNjhCOTEzQTRFNkNGM0UxRTEzMjZC QjIzQUY1MThFMUE0MDEzAAoJELsjr1GOGkATwOEP/jfYOhm6Tz/YzWPtPFAtrd6F gA5EEZ/KxGOxjPUIGhK3+uK6MhxSsDohO7cLWmz2MJd5PXv6scKOgsW7bvFwC0Lp z6GY5LhfH+x3W0Rx4vtsTWaVLz7QBABkNziiSNcux5sc3vBMn0QMEis6req4smRX Lz63WZSkTbrX63fxbTNwyTa0bd0ySzqCDbOA+ggVOgtxwzVwMC9+Y5YJhddmuWbO O4xXXghUKneYVHeMQ4dn5lsVa0t+3s//PASnwCn2aEK5cDSfGUE3jtfLHyxkgPPq XHnmVfbPZ93rlbKI0JBxK7bOkdmXu0J+DeEl8EadjudoO314Kopn5kJ1JoTs3pPj u+AuMG0xcbSUDzhCbE4a5wpdxg3OfC9gxmVeXfVNTfRo9N+gJdorp2lx9bMT/jXJ bTXgw5ZZWuRlZlBhOgzT6W/ta1lX3ZcNDpsOGrFNw4ASLo0RYf1NViC5oUhR0y3n AtToaBlMObmIavPBb0tdiZH+EWbQdRMwt3+bCveDruMx+xHzgLtvpZeP+GqAwG6M ZfAYha/ypLEUq6jYDNEd+Pl/+5MkTAsMulL6gzLVYn+D/RYTssO8sBTHRLvbHE4E 5appLQhjFbn0ZjKamGboIdqObtpJOln5M7jE+hcXMygtzVMIbApYGqxPZ5j4jL+A ZMW6beR+1pwAK6mqgfdj =p4Wy -----END PGP SIGNATURE-----
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?537CEACD.8090701>