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List:       freebsd-hackers
Subject:    Re: PostgreSQL benchmarks (now with Linux numbers)
From:       Doug Barton <dougb () FreeBSD ! org>
Date:       2012-02-24 0:17:10
Message-ID: 4F46D706.1060903 () FreeBSD ! org
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On 02/23/2012 05:22, John Baldwin wrote:
> On Wednesday, February 22, 2012 9:59:02 pm Doug Barton wrote:
> > On 02/22/2012 01:42, Ivan Voras wrote:
> > > The Dragonfly team has recently liberated their VM from the giant lock and \
> > > there are some interesting benchmarks comparing it to FreeBSD 9 and a 
> derivative of RedHat Enterprise Linux:
> > > 
> > > http://leaf.dragonflybsd.org/mailarchive/kernel/2011-11/msg00008.html
> > > 
> > > Other developments are described in their release notes: \
> > > http://www.dragonflybsd.org/release30/
> > 
> > The 4.5 times improvement by enabling kern.ipc.shm_use_phys is pretty
> > notable, what prevents us from enabling that by default?
> 
> It makes all your SYSV SHMs wired.  That's fine if you are running a dedicated
> server using SYSV SHMs where you want that process to use all the RAM in the
> machine (e.g. a pgqsl server).  It's not so great for a general purpose load
> where you would like an otherwise-idle process using SYSV SHMs to have the SHMs
> paged out to swap if other processes on the machine need memory and the box is
> under memory pressure.

I see, thanks for that explanation.


Doug

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