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Subject: Request for code review (for defect 20051)
Date: Wed, 29 Aug 2007 16:28:41 -0800
Message-ID: <BB375AF679D4A34E9CA8DFA650E2B04E03AEAD20@onstor-exch02.onstor.net>
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Thread-Topic: Request for code review (for defect 20051)
Thread-Index: AcfqnLdlIysbyk8pSRaPKvPSkIiS2g==
From: "Danqing Jin" <danqing.jin@onstor.com>
To: "Andy Sharp" <andy.sharp@onstor.com>

Andy,

I know you must be busy with you own project, but because you are the
well-recognized BSD/Linux kernel person, I have to bug you with this
code review...

Defect 20051 reports silient reboots of our filer.  Support was able
demostrate that silient reboot could effect under some stress condition
such as low memory.  With some further experiments by simulating such
low memory condition, I think this is likely coming from a reset from
our watchdog (ds1511_restart_watchdog()) on SSC since for some unknown
reason no one kicks the watchdog under such stress condition (even
including  high CPU load or CPU thrashing).  Now customer support would
like us to give some clues for such silient reboots.  So I was thinking
about logging to BSD syslog when things are getting quite bad:

1. when there are only small number of free pages
2. when the cpu load is greater than some very high number

For item 1, I eventually arrive at 60 pages (i.e., 6 times of
vm_page_free_reserved, which is 10 pages) after varying it between 20
and 250 pages.  For item 2, I am not as sure as this number could be
quite arbituary, and I am using 64 just to be not too chatty.  But
hopefully you may have some insight on this...

Many thanks in advance,
-Danqing-

P4 client:		danqingj-r301rel
Changed files:
/homes/danqingj/src/r301rel/openbsd/src/sys/vm/vm_meter.c
=09
/homes/danqingj/src/r301rel/openbsd/src/sys/vm/vm_page.c
