Request for testing - top 3.8b1 in the base system

William LeFebvre bill at
Sun Sep 28 16:17:04 UTC 2008

Edwin Groothuis wrote:
> On Sun, Sep 28, 2008 at 02:09:00AM -0700, Garrett Cooper wrote:
>> On Sun, Sep 28, 2008 at 1:14 AM, Alex Keda <admin at> wrote:
>>> Some strange. Count running processes not match with system top
> That has been explained in an email before.
>> I'm not sure I'm finding an issue, but I do find it interesting that...
>> 1. It takes a reasonably long amount of time for top to plateau the
>> WCPU field (approximately 8-10 iterations), whereas ps registering the
>> WCPU percentage value is almost instantaneous.

Top 3.8 doesn't display WCPU.  It is an antequated measure that is only 
maintained by the kernel so that ps can display it.  It no longer has 
any meaning to the scheduler, so why bother displaying it.

> With ps it takes 10 2 second steps to get the WCPU from 0 to 100,
> with the new top (which doesn't have WCPU (See Changes file, and
> the m_freebsd.c file, I don't know of the real reason behind it)
> anymore) goes from 0 to 100 in 2 2 second steps.

ps shows a decaying average as calculated by the kernel over the past 
minute and recorded in the proc structure.  Top calculates its own 
average based on the difference in cpu time between the last measurement 
and the current measurement.  The output from ps is fine when you want a 
single snapshot: you want it to show information averaged over a long 
period of time.  Top is showing you only what's going on right now, 
since the last update.  That's why percent CPU in top will climb to its 
final value so quickly.

Bill LeFebvre

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