NetBSD Problem Report #15688

Received: (qmail 13954 invoked from network); 21 Feb 2002 19:48:59 -0000
Message-Id: <200202211948.g1LJmvu01113@night-porter.duskware.de>
Date: Thu, 21 Feb 2002 20:48:57 +0100 (MET)
From: Martin Husemann <martin@duskware.de>
Reply-To: martin@duskware.de
To: gnats-bugs@gnats.netbsd.org
Subject: p_stats->p_cru.ru_utime.tv_sec may become negative
X-Send-Pr-Version: 3.95

>Number:         15688
>Category:       kern
>Synopsis:       p_stats->p_cru.ru_utime.tv_sec may become negative
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    kern-bug-people
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Feb 21 19:50:03 +0000 2002
>Closed-Date:    Sat May 13 17:37:05 +0000 2023
>Last-Modified:  Sat May 13 17:37:05 +0000 2023
>Originator:     Martin Husemann
>Release:        NetBSD 1.5ZA
>Organization:
>Environment:
System: NetBSD night-porter.duskware.de 1.5ZA NetBSD 1.5ZA (PORTER) #0: Tue Feb 12 21:59:35 CET 2002 martin@insomnia.duskware.de:/usr/src/sys/arch/i386/compile/PORTER i386
Architecture: i386
Machine: i386
>Description:

When you step the time backwards (or have ntpd runing causing this, i.e. just
after booting a machine, on first sync to the next timeserver), processes
started before this step may get a negative cummulated child cpu time.

Example from my sparc64 system:

168 ?? S    0:-2.74 /usr/pkg/sbin/upsmon 

This has been started just before ntpd, and ntpd did a few time resets
initially:

Feb 21 19:08:28 setting-sun ntpd[143]: time reset 5.511258 s
Feb 21 19:08:28 setting-sun ntpd[143]: kernel pll status change 41
Feb 21 19:28:51 setting-sun ntpd[143]: time reset 0.574144 s
Feb 21 19:49:19 setting-sun ntpd[143]: time reset 0.132181 s

I'm not sure fixing the scheduler to correctly handle this situation are
worth the additional context switch time.

>How-To-Repeat:
s/a
>Fix:
n/a
>Release-Note:
>Audit-Trail:

From: christos@zoulas.com (Christos Zoulas)
To: martin@duskware.de, kern-bug-people@netbsd.org,
	gnats-bugs@gnats.netbsd.org,
	gnats-admin@netbsd.org (GNATS Management)
Cc:  
Subject: Re: kern/15688: p_stats->p_cru.ru_utime.tv_sec may become negative
Date: Thu, 21 Feb 2002 15:06:36 -0500

 On Feb 21,  8:48pm, martin@duskware.de (Martin Husemann) wrote:
 -- Subject: kern/15688: p_stats->p_cru.ru_utime.tv_sec may become negative

 shouldn't process resources calculated using mono_time instead of microtime
 in calcru()?

 christos

 | When you step the time backwards (or have ntpd runing causing this, i.e. just
 | after booting a machine, on first sync to the next timeserver), processes
 | started before this step may get a negative cummulated child cpu time.
 | 
 | Example from my sparc64 system:
 | 
 | 168 ?? S    0:-2.74 /usr/pkg/sbin/upsmon 
 | 
 | This has been started just before ntpd, and ntpd did a few time resets
 | initially:
 | 
 | Feb 21 19:08:28 setting-sun ntpd[143]: time reset 5.511258 s
 | Feb 21 19:08:28 setting-sun ntpd[143]: kernel pll status change 41
 | Feb 21 19:28:51 setting-sun ntpd[143]: time reset 0.574144 s
 | Feb 21 19:49:19 setting-sun ntpd[143]: time reset 0.132181 s
 | 
 | I'm not sure fixing the scheduler to correctly handle this situation are
 | worth the additional context switch time.
 | 
 | >How-To-Repeat:
 | s/a
 | >Fix:
 | n/a
 | >Release-Note:
 | >Audit-Trail:
 | >Unformatted:
 -- End of excerpt from Martin Husemann


State-Changed-From-To: open->feedback
State-Changed-By: dholland@NetBSD.org
State-Changed-When: Sat, 13 May 2023 17:18:46 +0000
State-Changed-Why:
Is this still a thing?


State-Changed-From-To: feedback->closed
State-Changed-By: martin@NetBSD.org
State-Changed-When: Sat, 13 May 2023 17:37:05 +0000
State-Changed-Why:
Haven't seen it in years


>Unformatted:

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