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Date:      Sun, 22 Mar 2015 15:11:20 +0300 (MSK)
From:      Dmitry Morozovsky <marck@rinet.ru>
To:        Konstantin Belousov <kostikbel@gmail.com>
Cc:        svn-src-head@freebsd.org, Mark Linimon <linimon@lonesome.com>, svn-src-all@freebsd.org, src-committers@freebsd.org
Subject:   Re: svn commit: r280323 - head/sys/kern
Message-ID:  <alpine.BSF.2.00.1503221509370.71864@woozle.rinet.ru>
In-Reply-To: <20150321212416.GU2379@kib.kiev.ua>
References:  <201503211501.t2LF1Kj8052521@svn.freebsd.org> <20150321210341.GC15857@lonesome.com> <20150321210810.GT2379@kib.kiev.ua> <alpine.BSF.2.00.1503220014150.60253@woozle.rinet.ru> <20150321212416.GU2379@kib.kiev.ua>

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On Sat, 21 Mar 2015, Konstantin Belousov wrote:

> > > > >   Somewhat modernize the SysV shm code:
> > > > 
> > > > Is my understanding correct that postgres still uses shm?  If so,
> > > > has someone benchmarked the speedup?
> > > 
> > > Yes, some versions of Postgres still use SysV shm.  
> > 
> > To be clarified: IIUC, *all* contemporary versions of PostgreSQL do
> > use SHM for shatrd buffers (as PgSQL use process-per-connection model)
>
> No.  Recent versions use mmaped shared region for buffers.

Yes, starting from 9.3 main buffers are memory-mapped.  SysV SHM and Semaphores 
*are* still in use though.

(mainly for search engines)

Thanks for the clarification.

-- 
Sincerely,
D.Marck                                     [DM5020, MCK-RIPE, DM3-RIPN]
[ FreeBSD committer:                                 marck@FreeBSD.org ]
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*** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck@rinet.ru ***
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