Date: Wed, 21 May 2014 08:16:04 +0200 From: Palle Girgensohn <girgen@pingpong.net> To: =?utf-8?Q?"Gezeala_M._Bacu=C3=B1o_II"?= <gezeala@gmail.com> Cc: Adrian Chadd <adrian@freebsd.org>, "bsdmailinglist@googlegroups.com" <bsdmailinglist@googlegroups.com>, Petr Janda <janda.petr@gmail.com>, Steven Hartland <killing@multiplay.co.uk>, FreeBSD Mailing Lists <freebsd-performance@freebsd.org>, Sean Chittenden <sean@chittenden.org> Subject: Re: FreeBSD 10 and PostgreSQL 9.3 scalability issues Message-ID: <1BC3D447-2044-4AB8-B183-B83957BC9112@pingpong.net> In-Reply-To: <CAJKO3mUTwgiQenSLYfOxHrZxuPQ9kvUPC44MrbLjvpLE=toZQA@mail.gmail.com> 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>
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I got no response about how to grab performance data.=20 The PostgreSQL team is also making an effort by setting up machines dedicate= d to performance measuring and tuning.=20 And freebsd guys and PostgreSQL guys are apparently meeting at pgcon this we= ek.=20 We'll see where that leads.=20 In the mean time, if I for some pointers on how to grab performance data, I c= ould do some more tests.=20 Palle > 21 maj 2014 kl. 02:13 skrev Gezeala M. Bacu=C3=B1o II <gezeala@gmail.com>:= >=20 >=20 > Do you guys have any updates on this?=20 >=20 > -- >=20 > regards >=20 > gezeala bacu=C3=B1o II >=20 >=20 >> On Tue, Apr 22, 2014 at 11:52 PM, Palle Girgensohn <girgen@pingpong.net> w= rote: >>=20 >>=20 >> > 23 apr 2014 kl. 01:04 skrev Adrian Chadd <adrian@freebsd.org>: >> > >> > Hi, >> > >> > Are you able to repeat these tests (for both 9.2 and 9.3) whilst >> > grabbing some performance data from lock profiling and hwpmc? >>=20 >> I sure can, but I'd love some pointers as to how this is done. Please? :-= ) >>=20 >> > >> > The benchmarking is great but it doesn't tell us enough information as >> > to "why" things behave poorly compared to Linux and why the mmap drop >> > isn't so great. >>=20 >>=20 >> As per the discussion on postresql-hackers, the regression between pg9.2 a= nd pg9.3, which includes the sysv->mmap shift, *might* also exist, at least p= artly, on Linux as well. >>=20 >> The initial post in *this* thread does however indicate that freebsd perf= orms poorer than Linux and dragonflybsd, but does not really compare Postgre= SQL versions. >>=20 >> Just so we're not pursuing the wrong problem here, let's be open minded a= bout the definition of the problem. :-) >>=20 >> > >> > What about with more clients? 64? 128? 256? >>=20 >> My test went to 80. I can go higher as well, though other sources say 50 i= s a reasonable limit for PostgreSQL. >>=20 >> Palle >>=20 >>=20 >> > >> > >> > Thanks! >> > >> > >> > >> > -a >> > >> > >> >> On 21 April 2014 14:11, Palle Girgensohn <girgen@pingpong.net> wrote: >> >> >> >> >> >>> Den torsdagen den 20:e mars 2014 kl. 00:33:10 UTC+1 skrev Sean Chitte= nden: >> >>> >> >>>> As far as I know, the test was done on both UFS2 and ZFS and the >> >>>> difference was marginal. >> >>> >> >>> As Adrian pointed out, there is an mmap(2) mutex in the way. Starting= in >> >>> PostgreSQL 9.3, shared buffers are allocated out of mmap(2) instead o= f shm. >> >>> shm is only used to notify the PostgreSQL postmaster that a child pro= cess >> >>> exited/crashed (when a pid detaches from a shm segment, there is a ke= rnel >> >>> event, but there is no kernel event when detaching from an mmap(2) re= gion). >> >>> -sc >> >>> >> >>> http://www.postgresql.org/docs/9.3/static/release-9-3.html#AEN115039 >> >>> >> >>> >> >>>>>> Just want to share these pgbench results done by DragonFlyBSD, and= >> >>> would >> >>>>>> like some input on why these numbers look so bad and what can be d= one >> >>> to >> >>>>>> improve (ie. kernel tunables etc) the performance. >> >>> http://lists.dragonflybsd.org/pipermail/users/attachments/20140310/42= 50b961/attachment-0001.pdf >> >>>>> >> >>>>> >> >>>>> Do you have the ability to test with FreeBSD 8.x and 9.x to see if t= his >> >>> is >> >>>>> regression? >> >>>>> >> >>>>> Also you don't mention the FS used in each case, so I'm wondering i= f >> >>> you >> >>>>> used a ZFS install of FreeBSD which could help to explain things. >> >>> >> >>> >> >>> -- >> >>> Sean Chittenden >> >>> se...@chittenden.org <javascript:> >> >> Hi, >> >> >> >> There is a fresh thread about this in postgresql-hackers [1]. >> >> >> >> There are two parallel approaches suggested there, where one is to hav= e an >> >> option to continue using the old SYSV shared memory in PostgreSQL, and= the >> >> other is the suggestion that "somebody needs to hold the FreeBSD folks= ' >> >> feet to the fire about when we can expect to see a fix from their side= ." >> >> >> >> Looking at the original post in this thread, it seems to me that FreeB= SD >> >> has scalability problems beyond what the SYSV vs mmap change in Postgr= eSQL >> >> introduces? Check my test of PostgreSQL 9.2 vs 9.3 on FreeBSD 10.0 at [= 1]. >> >> The difference between PG92 and PG93 is not huge, ~17%. The difference= >> >> between FreeBSD and the other OS:es in this thread's original post's >> >> performance chart seems to be about a lot more? >> >> >> >> Palle >> >> >> >> [1] >> >> http://www.postgresql.org/message-id/2AE143D2-87D3-4AD1-AC78-CE2258230= C05@FreeBSD.org >> >> _______________________________________________ >> >> freebsd-performance@freebsd.org mailing list >> >> http://lists.freebsd.org/mailman/listinfo/freebsd-performance >> >> To unsubscribe, send any mail to "freebsd-performance-unsubscribe@free= bsd.org" >> _______________________________________________ >> 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" >=20
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