misc/126230: weird process cpu usage stats and weird load

[Jakub Jasinski]

The following reply was made to PR misc/126230; it has been noted by GNATS.

From: Jakub Jasinski <jakub.jasinski at utoronto.ca>
To: Gavin Atkinson <gavin at freebsd.org>
Cc: freebsd-gnats-submit at FreeBSD.org
Subject: Re: misc/126230: weird process cpu usage stats and weird load
Date: Thu, 7 Aug 2008 21:58:55 -0400

 Please note that all of the daemons that are consuming CPU and a.out
 (the compiled sample select() program) are select()-ing.  For
 example, look at the top output in the bug description and my last
 post with sample code.
 
 Also, please refer to (I filed a new bug report--this one more
 specific than "weird something or other"):
 http://www.freebsd.org/cgi/query-pr.cgi?pr=126289 (and refer to my
 previous post in this bug report.)
 
 I don't think a.out should be consuming ANY cpu while it's select()-ing,
 even on a 386.
 
 When comparing kern_select() in 6.2 and 7.0, the one slight difference
 is how thread locking is invoked...
 
 In any event, before and after:
 
 mail2# sysctl dev.cpu.0
 dev.cpu.0.%desc: ACPI CPU
 dev.cpu.0.%driver: cpu
 dev.cpu.0.%location: handle=\_PR_.CPU0
 dev.cpu.0.%pnpinfo: _HID=none _UID=0
 dev.cpu.0.%parent: acpi0
 dev.cpu.0.freq: 2322
 dev.cpu.0.freq_levels: 2322/-1 2031/-1 1741/-1 1451/-1 1161/-1 870/-1
 580/-1 290/-1 dev.cpu.0.cx_supported: C1/0
 dev.cpu.0.cx_lowest: C1
 dev.cpu.0.cx_usage: 100.00%
 
 mail2# sysctl dev.cpu.0
 dev.cpu.0.%desc: ACPI CPU
 dev.cpu.0.%driver: cpu
 dev.cpu.0.%location: handle=\_PR_.CPU0
 dev.cpu.0.%pnpinfo: _HID=none _UID=0
 dev.cpu.0.%parent: acpi0
 dev.cpu.0.freq: 2322
 dev.cpu.0.freq_levels: 2322/-1 2031/-1 1741/-1 1451/-1 1161/-1 870/-1
 580/-1 290/-1 dev.cpu.0.cx_supported: C1/0
 dev.cpu.0.cx_lowest: C1
 dev.cpu.0.cx_usage: 100.00%
 
 Thanks anyway.
 
 In the meantime, I'm going to try FreeBSD 6.3.
 
 On Thu, 7 Aug 2008 20:40:06 GMT
 Gavin Atkinson <gavin at freebsd.org> wrote:
 
 > The following reply was made to PR misc/126230; it has been noted by
 > GNATS.
 > 
 > From: Gavin Atkinson <gavin at FreeBSD.org>
 > To: bug-followup at FreeBSD.org
 > Cc:  
 > Subject: Re: misc/126230: weird process cpu usage stats and weird load
 > Date: Thu, 7 Aug 2008 21:35:17 +0100 (BST)
 > 
 >  Just a thought: what is the output of "sysctl dev.cpu.0" both
 > before, and after running rsync?  If for some reason your CPU is
 > ending up in a very low frequency mode, then it's not inconceivable
 > that daemons would appear to take a much greater share of the CPU
 > than usual.  Also, I'm assuming the clock maintains time normally?
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