Date: Wed, 21 May 2014 22:19:39 +0200 From: Palle Girgensohn <girgen@pingpong.net> To: Sean Chittenden <sean@chittenden.org> Cc: "freebsd-performance@freebsd.org" <freebsd-performance@freebsd.org>, Matthew Seaman <matthew@FreeBSD.org> Subject: Re: FreeBSD 10 and PostgreSQL 9.3 scalability issues Message-ID: <F47B306A-EB1E-4278-9460-02F25E09F738@pingpong.net> In-Reply-To: <sig.02185aa09c.5E8C4FB4-03A5-4460-8CA2-EF3DDBA659BB@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> <537CEACD.8090701@FreeBSD.org> <sig.02185aa09c.5E8C4FB4-03A5-4460-8CA2-EF3DDBA659BB@chittenden.org>
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21 maj 2014 kl. 22:05 skrev Sean Chittenden <sean@chittenden.org>: >>>> I did some tests with zfs, and results where appallingly bad, but that w= as with db size > ram.=20 >>>>>=20 >>>>> 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 wa= s some time ago, maybe things have improved. >>> I have some hardware that I ran with last week wherein I was *not* able t= o reproduce any performance difference between ZFS and UFS2. On both UFS2 an= d ZFS I was seeing the same performance when using a a RAID10 / set of mirro= rs. I talked with the Dragonfly folk who originally performed these tests an= d they also saw the same thing: no real performance difference between ZFS a= nd UFS. I ran my tests on a host with 16 drive, 10K SAS, 192GB RAM. I also c= reated a kernel profiling image and ran the 20 concurrent user test under kg= prof(1), dtrace, and pmcstat and have the results available: >>>=20 >>> http://people.freebsd.org/~seanc/pg9.3-fbsd10-profiling/ >>>=20 >>> There are some investigations that are ongoing as a result of these find= ings. The dfly methodology was observed when generating these results. Stay t= uned. -sc >>=20 >> 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) I never meant that it was the core of our problem. Zfs vs ufs is out of scop= e here.=20 >=20 > When the working set fits in RAM (OS + PG), there isn't a performance diff= erence between 9.2 and 9.3. >=20 > 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 >=20 I don't agree. My original measurements showed a 20% slowdown for a reasonab= ly small ( <RAM) pgbench database.=20 > -- > Sean Chittenden > sean@chittenden.org >=20 > _______________________________________________ > freebsd-performance@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-performance > To unsubscribe, send any mail to "freebsd-performance-unsubscribe@freebsd.= org"
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