SUMMARY:minf - What does this mean

From: Peter Tashkoff (informix@kiwi.co.nz)
Date: Wed Nov 05 1997 - 21:05:59 CST


Original question was to do with the meaning of minor faults. I had a hung informix thread spinning on a CPU and generating approx 25,000 minor faults per second.

Thanks to Arthur Hyun, Kevin Sheehan and Glenn Satchell for their answers.
This except from Arthurs reply covers most of the points:
============================
The pagedaemon finds a page that some process has mapped, steals it, and
marks it to be paged out. eventually, it gets paged out, and the page
is put onto the free list, but the data on the page is not yet modified.
when that process later tries to use the page, it gets a page fault.
if the page on the freelist has not yet been resused, and so contains the
original data, it is reclaimed. this is a minor fault.
if the page on the freelist has already been reused, the page has to be
pulled from disk or from swap. this is a major fault.
==========================
pages 200-201 of 'Sun Performance and Tuning' by Adrian Cockcroft covers this off.
Kevin Sheehan suggest using Truss and/ot pmap to find out what the spinning process is doing in the first place (Which is the root of the problem of course).
Thanks Guys.
rgds

Peter Tashkoff <tashkop@iname.com>
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