FreeBSD 10 and PostgreSQL 9.3 scalability issues

Gezeala M. Bacuño II gezeala at gmail.com
Wed May 21 00:14:33 UTC 2014


Do you guys have any updates on this?

--

regards

gezeala bacuño II


On Tue, Apr 22, 2014 at 11:52 PM, Palle Girgensohn <girgen at pingpong.net>wrote:

>
>
> > 23 apr 2014 kl. 01:04 skrev Adrian Chadd <adrian at 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?
>
> I sure can, but I'd love some pointers as to how this is done. Please? :-)
>
> >
> > 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.
>
>
> As per the discussion on postresql-hackers, the regression between pg9.2
> and pg9.3, which includes the sysv->mmap shift, *might* also exist, at
> least partly, on Linux as well.
>
> The initial post in *this* thread does however indicate that freebsd
> performs poorer than Linux and dragonflybsd, but does not really compare
> PostgreSQL versions.
>
> Just so we're not pursuing the wrong problem here, let's be open minded
> about the definition of the problem. :-)
>
> >
> > What about with more clients? 64? 128? 256?
>
> My test went to 80. I can go higher as well, though other sources say 50
> is a reasonable limit for PostgreSQL.
>
> Palle
>
>
> >
> >
> > Thanks!
> >
> >
> >
> > -a
> >
> >
> >> On 21 April 2014 14:11, Palle Girgensohn <girgen at pingpong.net> wrote:
> >>
> >>
> >>> Den torsdagen den 20:e mars 2014 kl. 00:33:10 UTC+1 skrev Sean
> Chittenden:
> >>>
> >>>> 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 of
> shm.
> >>> shm is only used to notify the PostgreSQL postmaster that a child
> process
> >>> exited/crashed (when a pid detaches from a shm segment, there is a
> kernel
> >>> event, but there is no kernel event when detaching from an mmap(2)
> region).
> >>> -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
> done
> >>> to
> >>>>>> improve (ie. kernel tunables etc) the performance.
> >>>
> http://lists.dragonflybsd.org/pipermail/users/attachments/20140310/4250b961/attachment-0001.pdf
> >>>>>
> >>>>>
> >>>>> Do you have the ability to test with FreeBSD 8.x and 9.x to see if
> this
> >>> is
> >>>>> regression?
> >>>>>
> >>>>> Also you don't mention the FS used in each case, so I'm wondering if
> >>> you
> >>>>> used a ZFS install of FreeBSD which could help to explain things.
> >>>
> >>>
> >>> --
> >>> Sean Chittenden
> >>> se... at 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 have
> 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 FreeBSD
> >> has scalability problems beyond what the SYSV vs mmap change in
> PostgreSQL
> >> 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-CE2258230C05@FreeBSD.org
> >> _______________________________________________
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