NetNews Usenet Archive 1992 #30/NN_1992_30.iso/spool/comp/unix/wizards/5232

Internet Message Format | 1992-12-15 | 1.8 KB

Xref: sparky comp.unix.wizards:5232 comp.unix.admin:6652
Path: sparky!uunet!usc!wupost!news.utdallas.edu!corpgate!bnrgate!bnr.co.uk!stl!crosfield!adf
From: [e-mail] (alex france)
Newsgroups: comp.unix.wizards,comp.unix.admin
Subject: Re: Causes Of Death On Heavily-Loaded UNIX System?
Message-ID: <[e-mail]>
Date: 15 Dec 92 11:58:49 GMT
References: <[e-mail]>
Organization: Crosfield Electronics, Hemel Hempstead, United Kingdom.
Lines: 31

In article <[e-mail]> [e-mail] (Will Estes) writes:
>A local SunOS host is experiencing extremely poor performance, and I am
>interested in understanding .....
>
>A typical symptom of poor performance on the subject system would be
>very slow character echoing in a vi session, with occasional delays of
>as much as 15 seconds when you type a character.
>

It has been my experienc that these kind of delays are caused when
there are too many processes chasing too few pages of memory. After a
couple of seconds of inactivity (i.e. you thinking a moment) your
vi process becomes eligible to have pages stolen, and in a very busy
system then proceeds to lose them fast. When you next type a character
your process goes back on the run queue, but as it runs faults almost
immediately and goes back on the queue waiting for the page to be
fetched from disk. This repeats itself several times until you finally
get enough pages in to echo the character.

Two solutions to this:-

i) Add more real memory.

ii) Whenever you pause to think, sit there with your hand rocking
    on space-delete-space-delete-.....

Alex.

# Alex France, Crosfield Electronics, | Phone: [phone] xt.3541 #
# Three Cherry Trees Lane,            | Fax:   [phone]         #
# Hemel Hempstead, HP2 7RH, England.  | Email: [e-mail]    #