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From: wcl@hjuxa.UUCP (Bill Loeffler)
Newsgroups: net.unix-wizards
Subject: Re: Why do ps, uptime (& probably others) check vmunix version?
Message-ID: <363@hjuxa.UUCP>
Date: Thu, 13-Feb-86 15:44:44 EST
Article-I.D.: hjuxa.363
Posted: Thu Feb 13 15:44:44 1986
Date-Received: Sat, 15-Feb-86 02:04:10 EST
References: <457@ur-helheim.UUCP>
Organization: Digital Equipment Corp. Holmdel, NJ
Lines: 18

In article <457@ur-helheim.UUCP>, badri@ur-helheim.UUCP (Badri Lokanathan) writes:

> So, here is my question. Why should ps (and any other program) examine the
> name of vmunix? This is particularly aggravating if a new kernel is being
> tested - I do not want to make too many changes, just in case.
> My apologies if I sound terribly naive!
> 

These commands check the time of /unix (vmunix). One System V, this
time is compared to the time of /etc/ps_data. /etc/ps_data contains
data nessary to lseek into /unix. If /unix was created after /etc/ps_data,
the commands update ps_data from the name list. This is done to save
the time and CPU required to read the name list each time ps is used.
You will note the first ps after linking a new UNIX will take longer.
-- 
Bill Loeffler
Digital Equipment Corp., Holmdel NJ 07733
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