CPU report in first line of "vmstat 1" is meaningless

John Baldwin jhb at freebsd.org
Tue Oct 19 13:16:19 UTC 2010


On Monday, October 18, 2010 3:30:11 pm Ed Maste wrote:
> On Mon, Oct 18, 2010 at 01:11:42PM -0500, Dan Nelson wrote:
> 
> > Maybe only blank it out on 32-bit machines?  It's a long, and a 64-bit
> > cp_time value essentially won't roll over (at 1 billion increments per
> > second it will roll over in 500 years; we currently increment 133 times per
> > second, I think).  If the value can be calculated accurately, it should be
> > printed.
> 
> Well, it won't roll over, but it's still different from all following
> lines (in that it effectively shows user/system/idle CPU usage since
> boot on the first line, and a snapshot over the last interval from then
> on).  I think it's still better to avoid printing it in that case.

All of the first line is that way though.  To do this "right" you'd need to
blank out the entire first line.

vm_stat and iostat on OS X have the current FreeBSD behavior (instant first
line that summarizes all activity since uptime), so I'd be inclined to just
leave the existing behavior.

-- 
John Baldwin


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