From owner-freebsd-bugs  Thu Jun 24 13:40: 6 1999
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Date: Thu, 24 Jun 1999 13:40:02 -0700 (PDT)
Message-Id: <199906242040.NAA66317@freefall.freebsd.org>
To: freebsd-bugs@FreeBSD.org
Cc: 
From: Mike Pritchard <mpp@mpp.pro-ns.net>
Subject: Re: kern/12381: Bad scheduling in FreeBSD
Reply-To: Mike Pritchard <mpp@mpp.pro-ns.net>
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The following reply was made to PR kern/12381; it has been noted by GNATS.

From: Mike Pritchard <mpp@mpp.pro-ns.net>
To: schuerge@cs.uni-sb.de
Cc: freebsd-gnats-submit@FreeBSD.ORG
Subject: Re: kern/12381: Bad scheduling in FreeBSD
Date: Thu, 24 Jun 1999 15:30:14 -0500 (CDT)

 > 
 > >Number:         12381
 > >Category:       kern
 > >Synopsis:       Bad scheduling in FreeBSD
 > >Confidential:   no
 > >Severity:       serious
 > >Priority:       medium
 > >Responsible:    freebsd-bugs
 > >State:          open
 > >Quarter:        
 > >Keywords:       
 > >Date-Required:
 > >Class:          sw-bug
 > >Submitter-Id:   current-users
 > >Arrival-Date:   Thu Jun 24 12:40:00 PDT 1999
 > >Closed-Date:
 > >Last-Modified:
 > >Originator:     Thomas Schürger
 > >Release:        FreeBSD 4.0-CURRENT
 > >Organization:
 > Universität Saarbrücken, Germany
 > >Environment:
 > FreeBSD starfire.heim-d.uni-sb.de 4.0-CURRENT FreeBSD 4.0-CURRENT #0: Tue Jun 15 13:36:03 CEST 1999     schuerge@starfire.heim-d.uni-sb.de:/usr/src/sys/compile/STARFIRE  i386
 > 
 > >Description:
 >...
 > is more desirable. It seems that renicing a process does not have a lot
 > of effect in FreeBSD.
 > 
 > >How-To-Repeat:
 > The problem can be verified by starting two CPU-intensive processes,
 > renicing one to +20 and watching the "top" output.
 
 Under -current:
 I just played around with this a little bit, and if I have just 1 nice 0
 cpu hog, and 1 or 2 nice 20 hogs, the nice 0 job gets about 1/2 of
 the cpu, and the two nice jobs get around 40 - 45% of the cpu.
 As I keep adding cpu hog nice 0 jobs, the nice 20 jobs get about 1/2 of the
 cpu as they did before.  If I have 3 nice 0 jobs running, the nice 20
 jobs get around zero % of the cpu, which is what I would expect.
 
 The man page for renice states that nice 20 jobs should only get 
 the cpu when nothing else wants it, which is not happening on lightly
 loaded systems.  Whether this is intentional or not, I don't know.
 One of our scheduling gurus will have to answer that.
 -- 
 Mike Pritchard
 mpp@FreeBSD.ORG or mpp@mpp.pro-ns.net
 


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