From: Jim C. Nasby <jnasby@pervasive.com>
To: Vivek Khera <vivek@khera.org>
Cc: Postgresql Performance <pgsql-performance@postgresql.org>
Subject: Re: Best OS & Configuration for Dual Xeon w/4GB & Adaptec RAID 2200S
Date: Tue, 21 Mar 2006 04:32:19 -0600
Message-ID: <20060321103219.GD15742@pervasive.com> (raw)
In-Reply-To: <8F6490E1-64E2-406B-A559-7DA8BA1EB197@khera.org>
References: <20060317221116.GA14661@juniper.net>
<8F6490E1-64E2-406B-A559-7DA8BA1EB197@khera.org>
On Mon, Mar 20, 2006 at 02:15:22PM -0500, Vivek Khera wrote:
> I think FreeBSD has a hard upper limit on the total ram it will use
> for disk cache. I haven't been able to get reliable, irrefutable,
> answers about it, though.
It does not. Any memory in the inactive queue is effectively your 'disk
cache'. Pages start out in the active queue, and if they aren't used
fairly frequently they will move into the inactive queue. From there
they will be moved to the cache queue, but only if the cache queue falls
below a certain threshold, because in order to go into the cache queue
the page must be marked clean, possibly incurring a write to disk. AFAIK
pages only go into the free queue if they have been completely released
by all objects that were referencing them, so it's theoretically
posisble for that queue to go to 0.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: jnasby@pervasive.com, vivek@khera.org
Subject: Re: Best OS & Configuration for Dual Xeon w/4GB & Adaptec RAID 2200S
In-Reply-To: <20060321103219.GD15742@pervasive.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox