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Date:      Tue, 27 Mar 2012 08:24:32 -0600
From:      "Samuel J. Greear" <sjg@evilcode.net>
To:        Doug Barton <dougb@freebsd.org>
Cc:        "hackers@freebsd.org" <hackers@freebsd.org>, Ivan Voras <ivoras@freebsd.org>
Subject:   Re: PostgreSQL benchmarks (now with Linux numbers)
Message-ID:  <CANY-Wm9%2BZzavsJqZ=4_66gZxt7ehh%2BAZTbeAZxAz7Tkg=syabA@mail.gmail.com>
In-Reply-To: <4F45AB76.5050201@FreeBSD.org>
References:  <b1732c99-eec2-4097-ad9c-f58979addf9f@email.android.com> <4F45AB76.5050201@FreeBSD.org>

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On Wed, Feb 22, 2012 at 7:59 PM, Doug Barton <dougb@freebsd.org> 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?
>
>
> Doug
>
> --


I just saw this, so I thought I would mention -- DragonFly was not doing a
great job allocating pv entries rapidly, which is needed during PostgreSQL
warm up -- This made shm_use_phys appear very effective. It only makes 1-2%
difference now on DragonFly, and only 1-2% difference on FreeBSD.

Sam



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