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From: bob@obiwan.uucp (Bob Willcox)
Subject: Re: Disk Thrashing question
Organization: Bob's Place, Austin TX
References: <1993Sep27.170443.444@doug.cae.wisc.edu>
Message-ID: <CE1M3C.97F@obiwan.uucp>
Date: Tue, 28 Sep 1993 02:40:09 GMT
Lines: 49
In article <1993Sep27.170443.444@doug.cae.wisc.edu>,
John Edward Tillema <tillemaj@cae.wisc.edu> wrote:
> I have had FreeBSD running for about a month or so on my 486
>now, and have noticed one major disadvantage to it compared to Linux
>(at least for me). It seems to take virtually nothing to cause me
>to start swapping like crazy, and even hang the system. My setup is:
>8 Meg Ram, 17 Meg swap space, 486/33, 340 Meg drive, with 300 for Unix.
>If i run anything in the background, or compile one program, or sun
>a comm program, you can hear the disk swapping like crazy and performance
>really drops(you can easily type a line of text before the first character
>is printed). I can even hang the system. I found a good way of doing
>this is the following:
> run olvwm.
> run XV and view a gif (or jpg, or probably anything), not necessarily
> large, the last one was only 200k.
> run emacs and load in a large file, here I'm talking about a 7 meg file.
>
> (Oh, and I also have the openwindows clock program running)
>
>The result I get is that it brings the emacs window up, and then all disk
>activity stops, the mouse doesn't respond, and there is no way to abort
>aside from a reboot of the system. In Linux, things would get slow, but
>never like that, and it never hung like that either, the only crashes I had
>was when running X+openwin in 8 megs w/o swap. I have narrowed down the
>FreeBSD kernel so that it only has devices I use (eg. got rid of the SCSI
>stuff). Is this to be expected? I wouldn't think so.
On one of my systems here (with 20MB of RAM), I have seen xv alone
expand up to 24MB of virtual storage. (This is when its built with
gnu malloc rather than the systems, otherwise its even worse.) I
would suspect that with only 8MB and all the memory intensive
programs you're running that it would page severly. Also, you may
well be running out of swap space which I will cause the system to
hang (at least it has for me).
Run "vmstat -s" to see what your VM/paging statistics are. I would
imagine alot of pageins and pageouts. Also, I often run top and
find it helpful in monitoring system and paging activity.
>Any ideas?
Sounds to me like you should either run fewer memory hungry programs
concurrently or buy more RAM :-)
--
Bob Willcox ...!{rutgers|ames}!cs.utexas.edu!uudell!obiwan!bob
Phone: 512 258-4224 (home)
512 838-3914 (work)