Re: Best OS & Configuration for Dual Xeon w/4GB & - Mailing list pgsql-performance

From Mark Kirkwood
Subject Re: Best OS & Configuration for Dual Xeon w/4GB &
Date
Msg-id 441F7847.5000406@paradise.net.nz
Whole thread Raw
In response to Re: Best OS & Configuration for Dual Xeon w/4GB &  (Mark Kirkwood <markir@paradise.net.nz>)
Responses Re: Best OS & Configuration for Dual Xeon w/4GB &  ("Jim C. Nasby" <jnasby@pervasive.com>)
List pgsql-performance
Mark Kirkwood wrote:
>
> I think Freebsd 'Inactive' corresponds pretty closely to Linux's
> 'Inactive Dirty'|'Inactive Laundered'|'Inactive Free'.
>

Hmmm - on second thoughts I think I've got that wrong :-(, since in
Linux all the file buffer pages appear in 'Cached' don't they...

(I also notice that 'Inactive Laundered' does not seem to be mentioned
in vanilla - read non-Redhat - 2.6 kernels)

So I think its more correct to say Freebsd 'Inactive' is similar to
Linux 'Inactive' + some|most of Linux 'Cached'.

A good discussion of how the Freebsd vm works is here:

http://www.freebsd.org/doc/en_US.ISO8859-1/books/arch-handbook/vm.html

In particular:

"FreeBSD reserves a limited amount of KVM to hold mappings from struct
bufs, but it should be made clear that this KVM is used solely to hold
mappings and does not limit the ability to cache data."

Cheers

Mark

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