Re: interpretation of sar output for AIX LPAR

From: ddf <oratune_at_msn.com>
Date: Thu, 16 Aug 2012 10:37:40 -0700 (PDT)
Message-ID: <a0aa09a7-c9c7-48d6-9959-6c3854267bbe_at_7g2000yqn.googlegroups.com>

On Aug 15, 11:11 pm, vsevolod.afanass..._at_gmail.com wrote:
> I am trying to understand the meaning of sar output for AIX LPAR.
> Example: this LPAR has entitlement = 7 CPU
>
> 14:58:10    %usr    %sys    %wio   %idle   physc   %entc
> 14:58:11      24       8       8      60    2.33    33.3
> 14:58:12      22      10       7      61    2.29    32.7
> 14:58:13      24      10      10      57    2.44    34.8
> 14:58:14      27      10       9      54    2.67    38.1
> 14:58:15      23       9       9      58    2.35    33.6
>
> My interpretation: at 14:58:12 this LPAR was allocated 2.29 physical CPU.
> Out of these 2.29 CPU it ised 22% in user mode and another 10% in kernel mode.
> So in physical CPU terms utilization was 2.29 x 32% = 0.73 CPU.
> Assuming all this utilization could be attributed to Oracle
> and remained constant for 1 hour I should see in Statspack for 1 hour interval
>
> Statistic                                       Time (s) % of DB time
> ----------------------------------- -------------------- ------------
> DB CPU                                             2,628
>
> as 3,600 x 0.73 = 2,628.
>
> Is it correct interpretation?

Yes. That, of course, presumes the kernel mode percentages apply to oracle-owned processes only, which is not the likely case as other nonoracle  processes are also using kernel calls. The figure you post would be the very maximum time Statspack would report for that hour window, with the minimum being 1813.68 (22% of the 2.29 CPUs x 3600). I would honestly expect the DB CPU elapsed time reported by Statspack to be in between those two values.

David Fitzjarrell Received on Thu Aug 16 2012 - 12:37:40 CDT