On Fri, 18 May 2001, Stephen C. Tweedie wrote:

Hi,

On Fri, May 18, 2001 at 07:44:39PM -0300, Rik van Riel wrote:

quoted

This is the core of why we cannot (IMHO) have a discussion
of whether a patch introducing new VM tunables can go in:
there is no clear overview of exactly what would need to be
tunable and how it would help.

It's worse than that.  The workload on most typical systems is not
static.  The VM *must* be able to cope with dynamic workloads.  You
might twiddle all the knobs on your system to make your database run
faster, but end up in such a situation that the next time a mail flood
arrives for sendmail, the whole box locks up because the VM can no
longer adapt.

That's the main problem with static parameters.  The problem you are
trying to solve is fundamentally dynamic in most cases (which is also
why magic numbers tend to suck in the VM.)

Yup.  The problems are dynamic even with my static test load.

Off the top of my head, if I could make a suggestion to the vm it
would be something like "don't let dirty pages lay idle any longer
than this" and maybe "reclaim cleaned pages older than that".

	-Mike

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