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To: hackers@FreeBSD.org
Subject: Re: 950210-SNAP, VM Free 
In-reply-to: Your message of "Wed, 15 Feb 1995 11:38:39 GMT."
             <199502151138.LAA00446@p5.spnet.com> 
Date: Wed, 15 Feb 1995 14:48:13 +0000
From: Ed Hudson <elh@p5.spnet.com>
Sender: hackers-owner@FreeBSD.org
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howdy.


	let me restate the problem...
	i'm experiencing a significant loss in performance
	under 950210-SNAP as a function of integrated system
	activity.

	it looks somewhat like a memory problem, but could
	be a problem with the file system (buffer cache?).

	after the system has been up a while, and done a bunch
	of work, and is then quiescent, the disk chatters a lot,
	lot more for all operations than when it reboots.

	i think that the csh time command's 'io' field correlates
	with both the sound that the disks make, and the loss of
	performance.  (with  loss in performance is measured as wall
	clock time)

	other than the number of io transactions reported by csh,
	and the loss in performance, the only macroscopic parameters
	that i can glean from the system  show a huge drop in
	free memory.


	a freshly booted system:

	time /bin/ls -LFC	: 0.0u 0.0s 0:00.06 66.6% 231+399k 0+0io 0pf+0w
	medium make		: 112.8u 24.3s 2:45.41 82.9% 869+1047k 336+1564io 8pf+0w



	after a big compile:

	time /bin/ls -LFC	: 0.0u 0.0s 0:00.57 14.0% 205+352k 24+0io 0pf+0w
	medium make		: 113.0u 25.9s 4:07.75 56.0% 862+1040k 5571+1564io 14pf+0w

	(the '/bin/ls time is actually the second (or third, etc) one, - the very
		first always takes a long time).





	please note the huge increase in the 'io' parameters,
	as well as the increase in wall clock time for both operations
	between the freshly booted system and the system after
	an hour's work.

	on an 'old' system, even if i kill -15 the x-server, so that i
	log out all of the way and xdm starts a new x server, i still
	experience the problem after i log back in..

	is this a memory problem?

	i don't know.  but a system that's been up for a while, and done
	a bunch of work, makes an awful lot more disk transactions than
	one that's very recently booted.

	people tell me that the numbers reported by top (below)
	are insufficient for understanding the memory stats.

	what top thinks	fresh	: Memory: 14M Act 1520K Inact 2860K Wired 13M Free 
	what top thinks	old	: Memory: 15M Act 1192K Inact 3220K Wired 3812K Free 3% Swap


	i've sup'ped, and i'm recompiling now, so i hope to understand if i have
	this problem with -current

	thanks for reading.

			-elh