Date: Mon, 12 Feb 2007 10:50:28 -0500 From: Lowell Gilbert <freebsd-questions-local@be-well.ilk.org> To: Cy Schubert <Cy.Schubert@komquats.com> Cc: freebsd-questions@freebsd.org Subject: Re: Tuning Question Message-ID: <44bqjziddn.fsf@be-well.ilk.org> In-Reply-To: <200702121532.l1CFWTE2054040@cwsys.cwsent.com> (Cy Schubert's message of "Mon\, 12 Feb 2007 07\:32\:29 -0800") References: <200702121532.l1CFWTE2054040@cwsys.cwsent.com>
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Cy Schubert <Cy.Schubert@komquats.com> writes: > Top's output, as is free memory on all O/S's these days, is bogus. It's the > size of the free memory pool which is available for immediate allocation. > Used memory is just as useless. It doesn't matter how much is swapped out, > what matters is how much I/O is being performed to support VM. I know at > work, which is an Oracle ghetto, paging should be kept at a minimum, > especially the SGA. Other apps can afford more. In the case of an average > FreeBSD system it's been guesswork. What I thought you should use top for is tracking the swapping rates. But that's not enough, because the acceptable rates will depend on what else is happening in the system. If the CPU is maxed out anyway (for example), then reducing the swapping will not improve your performance. My general approach to optimization is to identify a problem first. If you can't pin down a performance problem that you want to solve, then you aren't going to be able to prove that any changes fix that problem anyway.
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