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

[Alexander Best]

On Mon Oct 18 10, Dan Nelson wrote:
> In the last episode (Oct 18), Ed Maste said:
> > 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.
> 
> It is documented to do that, though, and could affect scripts that expect to
> see average-since-boot info on the first line.  iostat does the same, btw.
> 
> > On a related note I'm not sure if it makes sense to have the same
> > behaviour for the first line when an interval is set as when it is
> > invoked with no interval.

don't know if you have seen this, but this behavior has been documented in a
PR back in 2001:

http://www.freebsd.org/cgi/query-pr.cgi?pr=bin/30360

cheers.
alex

> 
> -- 
> 	Dan Nelson
> 	dnelson at allantgroup.com

-- 
a13x