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Path: utzoo!linus!gatech!seismo!umcp-cs!chris
From: chris@umcp-cs.UUCP (Chris Torek)
Newsgroups: net.unix-wizards
Subject: Re: 4.2 scheduler (and CPU utilization)
Message-ID: <2513@umcp-cs.UUCP>
Date: Tue, 10-Dec-85 09:30:59 EST
Article-I.D.: umcp-cs.2513
Posted: Tue Dec 10 09:30:59 1985
Date-Received: Wed, 11-Dec-85 21:59:19 EST
References: <1360@wanginst.UUCP> <879@psivax.UUCP> <3043@sun.uucp> <319@polaris.UUCP> <3062@sun.uucp> <324@polaris.UUCP>
Distribution: net
Organization: U of Maryland, Computer Science Dept., College Park, MD
Lines: 23

In article <324@polaris.UUCP> herbie@polaris.UUCP (Herb Chong) writes:

> [under heavy paging load] character echo stopped completely ...

Sounds like you ran into a driver bug that hung the system at IPL
15 or higher.  Character echo should NEVER stop, and noticeable
slowdown should be EXTREMELY rare even under the worst disk load
you can generate.

> the profile that we ran on the system later under "live" conditions
> indicated that 20% of the time was spent in namei and about 35% of
> the time in paging routines.  under the conditions we wanted to
> use the vax, adding more memory would have helped a lot but then
> fairly quickly we would have become CPU bound in namei.  hopefully,
> 4.3 bsd addresses this problem successfully.

It does.  We see an `average' name cache hit rate of at least 80%,
meaning that only 20% of the translations need to look at the buffer
cache/disks.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 4251)
UUCP:	seismo!umcp-cs!chris
CSNet:	chris@umcp-cs		ARPA:	chris@mimsy.umd.edu