On Fri, 18 May 2001, Rik van Riel wrote:

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

quoted

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 another problem, indeed ;)

Ingo, Mike, please keep this in mind when designing
tunables or deciding which test you want to run today
in order to look how the VM is performing.

I've bent your code up a bit.  I've not yet been tempted to replace
any of it with a knob ;-)  There is a little piece I'd like to see
thrown away though.. the loop in refill_inactive does nothing good.

The test I prefer is a good one for the area of vm performance I'm
most interested in.  It doesn't cover the full vm spectrum by any
means.  I don't have a setup (any) good for testing mondo network or
IO stuff.  I test a simple 'job one size to large' scenario.  Yes,
it's limited test coverage.. it's still legitimate.

Perhaps when you're evaluating vm performance, you should try my
simple test once in a while. :) I'll bet you a bogobeer right here
and now that when 2.4.5 hits the street you're going to be queried
by the big-busy-box folks wrt swap volume.

Basic rule for VM: once you start swapping, you cannot
win;  All you can do is make sure no situation loses
really badly and most situations perform reasonably.

I disagree with that.  I've seen a heavily swapping box run like
a scaulded ass ape many times.

	Warsteiner,

	-Mike

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux.eu.org/Linux-MM/