From: Claus Guttesen <kometen@gmail.com>
To: Sven Willenberger <sven@dmv.com>
Cc: Jon Brisbin <jon.brisbin@npcinternational.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: effective cache size on FreeBSD (WAS: Performance on SUSE w/
Date: Tue, 11 Oct 2005 19:23:59 +0200
Message-ID: <b41c75520510111023n7ae48ff8j@mail.gmail.com> (raw)
In-Reply-To: <1129043064.1975.22.camel@lanshark.dmv.com>
References: <b41c75520510110754g534d9fa8u@mail.gmail.com>
<1129043064.1975.22.camel@lanshark.dmv.com>
> > > Apparently this formula is no longer relevant on the FreeBSD systems as
> > > it can cache up to almost all the available RAM. With 4GB of RAM, one
> > > could specify most of the RAM as being available for caching, assuming
> > > that nothing but PostgreSQL runs on the server -- certainly 1/2 the RAM
> > > would be a reasonable value to tell the planner.
> > >
> > > (This was verified by using dd:
> > > dd if=/dev/zero of=/usr/local/pgsql/iotest bs=128k count=16384 to create
> > > a 2G file then
> > > dd if=/usr/local/pgsql/iotest of=/dev/null
> > >
> > > If you run systat -vmstat 2 you will see 0% diskaccess during the read
> > > of the 2G file indicating that it has, in fact, been cached)
> >
> > Thank you for your reply. Does this apply to FreeBSD 5.4 or 6.0 on
> > amd64 (or both)?
> >
>
> Not sure about 6.0 (but I don't know why it would change) but definitely
> on 5.4 amd64 (and I would imagine i386 as well).
Works on FreeBSD 6.0 RC1 as well. Tried using count=4096 on a 1 GB ram
box. Same behaviour as you describe above.
regards
Claus
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To: pgsql-performance@postgresql.org
Cc: kometen@gmail.com, sven@dmv.com, jon.brisbin@npcinternational.com
Subject: Re: effective cache size on FreeBSD (WAS: Performance on SUSE w/
In-Reply-To: <b41c75520510111023n7ae48ff8j@mail.gmail.com>
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