Date: Mon, 18 Oct 2010 14:39:16 -0500 From: Dan Nelson <dnelson@allantgroup.com> To: Ed Maste <emaste@freebsd.org> Cc: freebsd-current@freebsd.org Subject: Re: CPU report in first line of "vmstat 1" is meaningless Message-ID: <20101018193916.GD5644@dan.emsphone.com> In-Reply-To: <20101018193010.GA88783@sandvine.com> References: <20101018174331.GA80017@sandvine.com> <20101018181142.GC5644@dan.emsphone.com> <20101018193010.GA88783@sandvine.com>
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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. -- Dan Nelson dnelson@allantgroup.com
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