Date: Wed, 15 May 2002 11:25:14 -0700 (PDT) From: Norbert Papke <npapke@acm.org> To: freebsd-gnats-submit@FreeBSD.org Subject: docs/38118: New FAQ entry for amount of free memory Message-ID: <200205151825.g4FIPEcS089270@www.freebsd.org>
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>Number: 38118
>Category: docs
>Synopsis: New FAQ entry for amount of free memory
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-doc
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: wish
>Submitter-Id: current-users
>Arrival-Date: Wed May 15 11:30:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: Norbert Papke
>Release: 4.6-PRERELEASE
>Organization:
Proven Path
>Environment:
FreeBSD proven.2y.net 4.6-PRERELEASE FreeBSD 4.6-PRERELEASE #11: Tue May 14 16:58:29 PDT 2002 npapke@proven.2y.net:/usr/obj/usr/src/sys/NGP i386
>Description:
In a recent discussion on comp.unix.bsd.freebsd.misc John S. Dyson
<dyson@iquest.net> provided the following excellent description of free
memory caclulation. It should be added to the FAQ, possibly in
"Chapter 16 - Misc Questions". I have checked with John and he does
not object to his answers being used in this manner.
Q: How much free memory is available?
A: There are a couple of kinds of 'free memory'.
One kind is the amount of memory immediately available without
paging anything else out. That is approx the size of cache queue
+ size of free queue (with a derating factor, depending upon system
tuning.) Another kind of 'free memory ' is the total amount of
VM space. That can be complex, but is dependent upon the amount
of swap space and memory. Other kinds of 'free memory' descriptions
are also possible, but it is relatively useless to define these,
but rather it i s important to make sure that the paging rate is
kept low, and to avoid running out of swap space.
>How-To-Repeat:
n/a
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted:
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