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Question about Linux's kernel.all.cpu.* metrics

To: pcp@xxxxxxxxxxx
Subject: Question about Linux's kernel.all.cpu.* metrics
From: Martin Hicks <mort@xxxxxxx>
Date: Thu, 6 Aug 2009 12:54:40 -0500
User-agent: Mutt/1.5.17 (2007-11-01)
I went looking today at these metrics, and I'm a bit confused by the
values that are printed out.  For example:

        case 23: /* kernel.all.cpu.idle */
            _pm_assign_utype(_pm_idletime_size, atom,
                        1000 * (double)proc_stat.idle / proc_stat.hz);
            break;


What's the goal of the multiplication and division by HZ?  This just
looks plain wrong to me, but maybe I'm missing something.  Additional
support for this is that the idle metric in PCP advances by 10x what it
should (200/sec):

mort@laplace:~$ pmdumptext -t 1 kernel.all.cpu.idle
Thu Aug  6 13:52:34     ?
Thu Aug  6 13:52:35     1989.809
Thu Aug  6 13:52:36     2000.010

mort@laplace:~$ pminfo -f kernel.all.hz hinv.ncpu

kernel.all.hz
    value 100

hinv.ncpu
    value 2


mh

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