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Old 09-06-2013, 07:03 AM   #1
LinuxLover
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Registered: Feb 2004
Distribution: Solaris 10/11 , RHEL 6 ,AIX 7.1
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How AIX calculate CPU %idle


Hi,
I am striving hard to unveil the formula by which AIX tools ( like lparstat ) are calculating the CPU usage percentage. like in below example

AIX 5.3
Server : Power 780 LPAR

bash-4.2$ lparstat -i | grep -i cpu
Online Virtual CPUs : 8
Maximum Virtual CPUs : 8
Minimum Virtual CPUs : 1
Maximum Physical CPUs in system : 64
Active Physical CPUs in system : 31
Active CPUs in Pool : 31
Shared Physical CPUs in system : 31
Physical CPU Percentage : 10.00%
Desired Virtual CPUs : 8



and lparstat demonstrate

%user %sys %wait %idle physc %entc
64.5 17.1 1.4 17.0 4.26 532



Machine is currently using 5 time of its entitle capacity ( which is .80 for this lpar ) and f physical CPU core for this becomes 4.26 cores which is understand able.


But how the %idle value is 17 unable to understand.



All the docs just stuck with one hint

" *** %idle
For uncapped partitions with a current physical processor consumption above their entitled capacity, the percentage becomes relative to the number of physical processor consumed (physc). ***"



can some one elaborate how below statics are being calculated by this.

%user %sys %wait %idle
64.5 17.1 1.4 17.0
 
Old 09-06-2013, 10:26 AM   #2
Michael AM
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Registered: May 2006
Distribution: AIX 5.3, AIX 6.1, AIX 7.1
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AIX 5.3 on a 780 is unusual these days.

Need to know the oslevel as well.

The output of sar -P ALL 5 1

could help here. Personally, i use the command mpstat, but sar is perhaps more neutral aka *nix command.
 
Old 09-07-2013, 12:17 PM   #3
Michael AM
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Registered: May 2006
Distribution: AIX 5.3, AIX 6.1, AIX 7.1
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OK - lets get some examples:

While under entitlement, %idle is mostly the unused entitlement. The processor was not actually busy.

Code:
# lparstat 5

System configuration: type=Shared mode=Uncapped smt=4 lcpu=8 mem=2048MB psize=6 ent=0.50 

%user  %sys  %wait  %idle physc %entc  lbusy   app  vcsw phint  %nsp
----- ----- ------ ------ ----- ----- ------   --- ----- ----- -----
  0.0   0.2    0.0   99.8  0.00   0.7    1.1  5.98   175     0    69 
  0.0   0.2    0.0   99.8  0.00   0.6    0.8  5.99   173     0    69 
  0.0   0.2    0.0   99.8  0.00   0.6    1.4  5.99   174     0    69 
  0.0   0.2    0.0   99.8  0.00   0.6    0.8  5.99   173     0    69
In the next code block(s) I will be running a single command:

Code:
dd if=/dev/urandom of=/dev/null
and be changing the smtctl settings to show the changes in the output of lparstat.

Code:
System configuration: type=Shared mode=Uncapped smt=4 lcpu=8 mem=2048MB psize=6 ent=0.50 

%user  %sys  %wait  %idle physc %entc  lbusy   app  vcsw phint  %nsp
----- ----- ------ ------ ----- ----- ------   --- ----- ----- -----
  0.1   0.3    0.0   99.6  0.00   0.9    0.8  5.97   176     0    69 
  0.0   0.2    0.0   99.8  0.00   0.6    1.4  5.99   174     0    69 
  3.8  54.0    0.0   42.2  1.13 225.9   13.2  4.81 29195     0    69 
  3.4  48.9    0.0   47.7  1.55 311.0   16.7  4.35 45083     0    69 
  3.3  47.5    0.0   49.1  1.59 318.5   17.0  4.31 46873     0    69 
  3.4  49.7    0.0   47.0  1.51 301.1   16.8  4.41 44387     0    69 
  3.4  48.5    0.0   48.1  1.56 311.1   16.1  4.35 45883     0    69 
System configuration changed. The current iteration values may be inaccurate.
  4.9  53.9    0.2   41.0  1.59 317.4   19.8  4.31 41699     2    69
Now the command reports the output in ST (single-threaded) mode, aka SMT1 - so lcpu=2 (1 for each virtual processor).
Code:
System configuration: type=Shared mode=Uncapped smt=Off lcpu=2 mem=2048MB psize=6 ent=0.50 
%user  %sys  %wait  %idle physc %entc  lbusy   app  vcsw phint  %nsp
----- ----- ------ ------ ----- ----- ------   --- ----- ----- -----
  6.0  78.0    0.0   16.0  1.50 299.9   64.9  4.26 38558     0    69 
  6.0  77.7    0.0   16.3  1.51 301.7   63.1  4.25 38569     0    69 
  6.0  77.7    0.0   16.3  1.51 301.4   64.0  4.25 38176     0    69 
  5.9  77.5    0.0   16.6  1.51 302.9   57.8  4.24 38206     0    69 
  6.0  77.1    0.0   17.0  1.59 318.5   62.2  4.20 31401     0    69 
  5.2  77.1    0.0   17.7  1.63 326.6   62.6  4.18 27756     0    69 
System configuration changed. The current iteration values may be inaccurate.
  4.7  68.7    0.1   26.6  1.64 328.8   36.9  4.21 149753     1    69
Back to SMT4 mode - so lcpu=8 (4 for each virtual processor).
Code:
System configuration: type=Shared mode=Uncapped smt=4 lcpu=8 mem=2048MB psize=6 ent=0.50 
%user  %sys  %wait  %idle physc %entc  lbusy   app  vcsw phint  %nsp
----- ----- ------ ------ ----- ----- ------   --- ----- ----- -----
  3.2  48.8    0.1   47.9  1.61 322.3   16.9  4.30 43177     2    69 
  3.1  48.0    0.0   48.9  1.67 334.9   16.8  4.24 42277     0    69 
  3.2  48.9    0.0   48.0  1.60 319.1   16.6  4.32 40851     0    69 
  3.3  48.2    0.0   48.5  1.68 335.1   16.9  4.24 39905     0    69
If you compare the %idle/physc/%entc columns you will see the idle number is much higher with SMT4 than with ST (ST:SMT4::16:46) -i.e. factor 3 - while physc/%entc differ somewhat (physc/%entc values do not change by more than 10 to 15%).

WHAT about AIX 5.3?
AIX 5.3 does not support SMT4 - it only know SMT2 and ST, so a similar behavior shows up, but the differences are less.

Code:
System configuration: type=Shared mode=Uncapped smt=On lcpu=4 mem=2048MB psize=6 ent=0.50 

%user  %sys  %wait  %idle physc %entc  lbusy   app  vcsw phint  %nsp
----- ----- ------ ------ ----- ----- ------   --- ----- ----- -----
  0.0   0.2    0.0   99.8  0.00   0.5    0.9  5.99   153     0    69 
  0.0   0.2    0.0   99.8  0.00   0.5    0.5  5.99   153     0    69 
  0.0   0.2    0.0   99.7  0.00   0.6    0.9  5.99   155     0    69 
  4.0  60.1    0.0   35.9  0.45  89.4   10.2  5.48 10655     0    69 
  4.1  64.2    0.0   31.7  1.49 297.6   34.0  4.36 44438     0    69 
  4.1  61.9    0.0   34.1  1.61 322.6   32.8  4.22 46030     1    69 
  4.2  62.5    0.0   33.3  1.59 317.8   33.2  4.25 44558     0    69 
  4.2  62.5    0.0   33.4  1.59 318.0   32.9  4.25 43855     1    69 
  3.9  60.0    0.0   36.0  1.56 312.6   33.6  4.28 43952     0    69 
System configuration changed. The current iteration values may be inaccurate.
  5.0  72.7    0.0   22.2  1.56 312.5   46.9  4.27 3689348814741837312     1    69 

System configuration: type=Shared mode=Uncapped smt=Off lcpu=2 mem=2048MB psize=6 ent=0.50 
%user  %sys  %wait  %idle physc %entc  lbusy   app  vcsw phint  %nsp
----- ----- ------ ------ ----- ----- ------   --- ----- ----- -----
  5.2  77.4    0.2   17.2  1.63 325.4   65.2  4.19 27456     0    69 
  5.2  77.1    0.0   17.7  1.64 327.0   62.8  4.18 27937     0    69 
  5.2  77.2    0.0   17.6  1.64 327.5   65.1  4.18 28054     0    69 
  5.9  78.6    0.0   15.5  1.53 306.7   63.5  4.28 27373     0    69 
  6.3  78.6    0.0   15.1  1.49 298.2   63.5  4.27 33832     1    69 
System configuration changed. The current iteration values may be inaccurate.
  4.1  59.9    0.1   35.9  1.44 287.8   34.0  4.40 411279     1    69 

System configuration: type=Shared mode=Uncapped smt=On lcpu=4 mem=2048MB psize=6 ent=0.50 
%user  %sys  %wait  %idle physc %entc  lbusy   app  vcsw phint  %nsp
----- ----- ------ ------ ----- ----- ------   --- ----- ----- -----
  4.2  61.1    0.0   34.7  1.50 300.2   32.6  4.32 47216     0    69 
  4.1  61.7    0.0   34.2  1.41 281.1   33.2  4.44 43958     0    69 
  4.3  62.4    0.0   33.3  1.48 295.1   32.7  4.36 46361     0    69 
  4.0  60.4    0.0   35.6  1.42 284.6   32.2  4.42 44246     0    69
Now - to see what is going on in more detail you need a different command, sar or mpstat.

sar output is "well known layout"
Code:
# sar -P ALL 5 1

AIX mylpar01 1 6 00F6601D4C00    09/07/13

System configuration: lcpu=8 ent=0.50 mode=Uncapped 

12:01:12 cpu    %usr    %sys    %wio   %idle   physc   %entc
12:01:17  0       10      53       0      37    0.00     0.4
          1        0       3       0      97    0.00     0.2
          2        0       2       0      98    0.00     0.2
          3        0       3       0      97    0.00     0.1
          4        0      46       0      54    0.00     0.0
          5        0       6       0      94    0.00     0.0
          6        0       6       0      94    0.00     0.0
          7        0       6       0      94    0.00     0.0
          U        -       -       0      99    0.50    99.1
          -        0       0       0     100    0.00     0.9
Compare this with mpstat output

Code:
# mpstat 5 1

System configuration: lcpu=8 ent=0.5 mode=Uncapped 

cpu  min  maj  mpc  int   cs  ics   rq  mig lpa sysc us sy wa id   pc  %ec  lcs
  0   21    0    0  161   79    0    1    1 100  149 17 57  0 26 0.00  0.5  122
  1    0    0    0    8    0    0    0    1 100    0  0  3  0 97 0.00  0.2    8
  2    0    0    0    8    0    0    0    1 100    0  0  3  0 97 0.00  0.1    8
  3    0    0    0    8    0    0    0    1 100    0  0  2  0 98 0.00  0.2    8
  4    0    0    0   13    0    0    0    1 100    0  0 45  0 55 0.00  0.0   14
  5    0    0    0    0    0    0    0    1 100    0  0  6  0 94 0.00  0.0    0
  6    0    0    0    0    0    0    0    1 100    0  0  5  0 95 0.00  0.0    0
  7    0    0    0    0    0    0    0    1 100    0  0  6  0 94 0.00  0.0    0
  U    -    -    -    -    -    -    -    -   -    -  -  -  0 99 0.50 99.2    -
ALL   21    0    0  198   79    0    1    8 100  149  0  0  0 100 0.00  1.0  160
In both outputs the U row shows the physc/pc/physical amount unused - and how it is accounted to idle. Further both have an -/ALL line that is comparable with what lparstat/vmstat single line output gives.

So to close this post - the "detailed" view - same command in the background (idle, command starts, switch to ST with command
Quote:
# smtctl -m off
and turn it back on again with
Quote:
# smtctl -t 4
(AIX 5.3 will use # smtctl -m on instead.

Code:
# mpstat 5

System configuration: lcpu=8 ent=0.5 mode=Uncapped 

cpu  min  maj  mpc  int   cs  ics   rq  mig lpa sysc us sy wa id   pc  %ec  lcs
  0    2    0    0  141   80    0    1    1 100   38 10 56  0 34 0.00  0.3  103
  1    0    0    0    8    0    0    0    1 100    0  0  3  0 97 0.00  0.1    8
  2    0    0    0    8    0    0    0    1 100    0  0  3  0 97 0.00  0.1    8
  3    0    0    0    8    0    0    0    1 100    0  0  3  0 97 0.00  0.1    8
  4    0    0    0   13    0    0    0    1 100    0  0 45  0 55 0.00  0.0   14
  5    0    0    0    0    0    0    0    1 100    0  0  6  0 94 0.00  0.0    0
  6    0    0    0    0    0    0    0    1 100    0  0  6  0 94 0.00  0.0    0
  7    0    0    0    0    0    0    0    1 100    0  0  6  0 94 0.00  0.0    0
  U    -    -    -    -    -    -    -    -   -    -  -  -  0 99 0.50 99.4    -
ALL    2    0    0  178   80    0    1    8 100   38  0  0  0 100 0.00  0.7  141
--------------------------------------------------------------------------------
  0   92    0    0  173   98    1    1    0 100  542 27 56  0 17 0.00  0.6  127
  1    0    0    0    9    0    0    0    0   -    0  0  2  0 98 0.00  0.2    9
  2    0    0    0    9    0    0    0    0   -    0  0  2  0 98 0.00  0.2   10
  3    0    0    0    9    0    0    0    0   -    0  0  2  0 98 0.00  0.2   10
  4    0    0    0   16    0    0    0    0   -    0  0 47  0 53 0.00  0.0   17
  5    0    0    0    0    0    0    0    0   -    0  0  2  0 98 0.00  0.0    0
  6    0    0    0    0    0    0    0    0   -    0  0  2  0 98 0.00  0.0    0
  7    0    0    0    0    0    0    0    0   -    0  0  2  0 98 0.00  0.0    0
  U    -    -    -    -    -    -    -    -   -    -  -  -  0 99 0.49 98.8    -
ALL   92    0    0  216   98    1    1    0 100  542  0  0  0 99 0.01  1.2  173
--------------------------------------------------------------------------------
  0   27    0    0  176 18898  493    2   81 100 17653  6 75  0 19 0.23 41.8 5415
  1    0    0    0   41 19513  618    0   77 100 5000  3 53  0 44 0.14 25.6 6008
  2    0    0    0    7    0    0    0    1 100    0  0  0  0 100 0.05  8.8    8
  3    0    0    0    7    0    0    0    1 100    0  0  0  0 100 0.05  8.8    8
  4    0    0    0   28  232    3    0   13 100 6154  6 93  0  1 0.14 24.7   94
  5    0    0    0    3  449    1    1    4 100  778  2 24  0 74 0.03  4.8  237
  6    0    0    0    2    0    0    0    1 100    0  0  0  0 100 0.02  3.4    2
  7    0    0    0    2    0    0    0    1 100    0  0  0  0 100 0.02  3.5    2
ALL   27    0    0  266 39092 1115    3  179 100 29585  4 56  0 40 0.67 134.5 11774
--------------------------------------------------------------------------------

cpu  min  maj  mpc  int   cs  ics   rq  mig lpa sysc us sy wa id   pc  %ec  lcs
  0    0    0    0  261 54415   20    1   84 100 33567  5 46  0 49 0.29 17.0 19286
  1    0    0    0   99 42655   12    0   73 100 2510  0 36  0 63 0.22 12.7 19431
  2    0    0    0    9    0    0    0    0   -    0  0  0  0 100 0.11  6.6   10
  3    0    0    0    9    0    0    0    0   -    0  0  0  0 100 0.11  6.6    9
  4    0    0    0  100 3177    7    1   16 100 28392  6 89  0  6 0.52 30.6 1061
  5    0    0    0   99   18   18    0    0 100 7623  3 58  0 39 0.23 13.2  100
  6    0    0    0    9    0    0    0    0   -    0  0  0  0 100 0.11  6.6   10
  7    0    0    0    9    0    0    0    0   -    0  0  0  0 100 0.11  6.6   10
ALL    0    0    0  595 100265   57    2  173 100 72092  3 47  0 50 1.72 343.1 39917
--------------------------------------------------------------------------------
  0    0    0    0  261 51139   17    1   82 100 28171  5 46  0 49 0.28 16.7 19480
  1    0    0    0  100 39832   17    1   70 100 4554  1 47  0 51 0.24 14.3 17175
  2    0    0    0    9    0    0    0    1 100    0  0  0  0 100 0.11  6.5   10
  3    0    0    0    9    0    0    0    1 100    0  0  0  0 100 0.11  6.6   10
  4    0    0    0  100 4803   11    1   22 100 34422  6 92  0  2 0.59 35.8 1603
  5    0    0    0   99 4988    6    0    3 100 5179  1  9  0 90 0.12  7.3 2875
  6    0    0    0    9    0    0    0    1 100    0  0  0  0 100 0.11  6.4   10
  7    0    0    0    9    0    0    0    1 100    0  0  0  0 100 0.11  6.4   10
ALL    0    0    0  596 100762   51    3  181 100 72326  3 48  0 49 1.66 331.1 41173
--------------------------------------------------------------------------------
  0    0    0    0  261 64902   14    1   94 100 36135  5 44  0 51 0.30 17.2 21012
  1    0    0    0  101 39090   11    1   86 100  871  0 34  0 66 0.21 11.9 17546
  2    0    0    0    9    0    0    0    0   -    0  0  0  0 100 0.12  6.7   10
  3    0    0    0    9    0    0    0    0   -    0  0  0  0 100 0.12  6.7    9
  4    0    0    0  100    9    4    1    7 100 36969  6 94  0  0 0.65 37.8   99
  5    0    0    0   50    0    0    0    0   -    0  0  0  0 100 0.11  6.6   51
  6    0    0    0    9    0    0    0    0   -    0  0  0  0 100 0.11  6.6    9
  7    0    0    0    9    0    0    0    0   -    0  0  0  0 100 0.11  6.6    9
ALL    0    0    0  548 104001   29    3  187 100 73975  3 47  0 50 1.73 346.9 38745
--------------------------------------------------------------------------------

cpu  min  maj  mpc  int   cs  ics   rq  mig lpa sysc us sy wa id   pc  %ec  lcs

System configuration changed. The current iteration values may be inaccurate.
  0  928    0    0  267 62051   95    3  149 100 34486  6 54  0 40 0.40 23.8 19415
  1    0    0    0   68 32559   15    0   69 100 1427  1 41  0 58 0.24 13.9 3681986945049576960
  2    0    0    0    6    0    0    0    4 100    0  0  0  0 100 0.12  6.9 3681986945049812480
  3    0    0    0    6    0    0    0    3 100    0  0  0  0 100 0.12  6.9 3681986945049812992
  4   63    0    1  106 8708   99    2  106 100 36901  6 91  0  3 0.72 42.8 2265
  5  409    0    0   10  611   31    0   29 100  810  1 16  0 83 0.13  7.8 3681986945049708032
  6  562    0    1   11    2    2    0   12 100    0  0  4  0 96 0.12  6.9 3681986945049818624
  7  475    0    2    7    2    2    0   10 100    0  0  3  0 97 0.12  6.9 3681986945049818624
ALL 2437    0    4  481 103933  244    5  382 100 73624  4 57  0 39 1.96 392.2 3645177596589017776
--------------------------------------------------------------------------------

System configuration: lcpu=2 ent=0.5 mode=Uncapped 

cpu  min  maj  mpc  int   cs  ics   rq  mig lpa sysc us sy wa id   pc  %ec  lcs
  0    0    0    0  261 74067   42    3   84 100 37103  5 71  0 24 0.77 46.9 18239
  4    0    0    0  100 39635   30    1   85 100 36874  5 83  0 12 0.87 53.1 9805
ALL    0    0    0  361 113702   72    4  169 100 73977  5 77  0 18 1.63 326.6 28044
--------------------------------------------------------------------------------
  0    0    0    0  261 75835   51    1  101 100 37089  5 70  0 25 0.76 46.4 18728
  4    0    0    0  100 36386   33    2  106 100 36764  5 84  0 11 0.88 53.6 9091
ALL    0    0    0  361 112221   84    3  207 100 73853  5 77  0 18 1.63 326.9 27819
--------------------------------------------------------------------------------
  0   56    0    0  265 96641   43    3   77 100 37344  5 60  0 35 0.69 42.3 23804
  4    0    0    0  102 16426   29    1   77 100 37257  6 90  0  4 0.94 57.7 4134
ALL   56    0    0  367 113067   72    4  154 100 74601  5 77  0 18 1.64 327.3 27938
--------------------------------------------------------------------------------

cpu  min  maj  mpc  int   cs  ics   rq  mig lpa sysc us sy wa id   pc  %ec  lcs
  0    0    0    0  265 92184   50    3  109 100 37100  5 62  0 33 0.70 42.8 22740
  4    0    0    0  114 20005   34    1  112 100 37506  6 89  0  5 0.93 57.2 5052
ALL    0    0    0  379 112189   84    4  221 100 74606  5 77  0 17 1.63 326.0 27792
--------------------------------------------------------------------------------

System configuration changed. The current iteration values may be inaccurate.
  0  413    0    0   49 10009   16    1  152 100 5986  5 74  0 20 0.66 131.2 2729
  1   20    0    0    4 1079    0    1   22 100   92  1 50  0 49 0.01  1.8 78989
  2   46    0    0    4  149    2    0   36 100  157  3 44  1 52 0.01  1.3 1669
  3    6    0    0    4  198    2    0   43 100  198  4 22  1 73 0.00  1.0 1654
  4  115    0    0   18 8711   15    1  128 100 6493  5 78  0 16 0.72 144.5 2251
  5    0    0    0    4   52    1    1   13 100  559  4 76  0 20 0.01  2.6 37099
  6    0    0    0    3    2    0    0    5 100    0  0  7  0 93 0.00  0.8  152
  7    1    0    0    3    0    0    0    3 100   92  2 36  0 62 0.01  1.0  122
  U    -    -    -    -    -    -    -    -   -    -  -  -  0 40 0.20 40.0    -
ALL  601    0    0   89 20200   36    4  402 100 13577  3 43  0 53 1.42 284.3 124665
--------------------------------------------------------------------------------

System configuration: lcpu=8 ent=0.5 mode=Uncapped 

cpu  min  maj  mpc  int   cs  ics   rq  mig lpa sysc us sy wa id   pc  %ec  lcs
  0    0    0    0  260 35094   24    1   84 100 23241  5 56  0 39 0.29 17.3 11094
  1    0    0    0  100 19741   58    1   52 100 13626  4 74  0 23 0.35 21.0 7808
  2    0    0    0   73    0    0    0    1 100    0  0  0  0 100 0.11  6.6   73
  3    0    0    0   42    0    0    0    1 100    0  0  0  0 100 0.11  6.6   42
  4    0    0    0  101 17396   12    1   58 100 33238  6 78  0 16 0.42 24.7 8031
  5    0    0    0   99 33946    9    0   24 100 1078  0 32  0 67 0.19 11.3 13024
  6    0    0    0   58    0    0    0    1 100    0  0  0  0 100 0.11  6.4   59
  7    0    0    0   79    0    0    0    1 100    0  0  0  0 100 0.11  6.4   79
ALL    0    0    0  812 106177  103    3  222 100 71183  3 48  0 49 1.69 337.9 40210
--------------------------------------------------------------------------------
  0    0    0    0  260 43002   19    2   81 100 30133  5 58  0 37 0.33 18.9 14645
  1    0    0    0  100 34478   23    1   51 100 5703  2 53  0 45 0.26 15.2 13884
  2    0    0    0    9    0    0    0    0   -    0  0  0  0 100 0.11  6.6    9
  3    0    0    0    9    0    0    0    0   -    0  0  0  0 100 0.11  6.6    9
  4    0    0    0  102 15366   17    1   48 100 33282  6 85  0  9 0.51 29.6 5522
  5    0    0    0   99 13632    7    0   17 100 2563  1 34  0 65 0.17 10.1 5354
  6    0    0    0    9    0    0    0    0   -    0  0  0  0 100 0.11  6.5   10
  7    0    0    0    9    0    0    0    0   -    0  0  0  0 100 0.11  6.5   10
ALL    0    0    0  597 106478   66    4  197 100 71681  3 47  0 49 1.72 344.7 39443
WOW! What to look at?

See lines like this:

Code:
cpu  min  maj  mpc  int   cs  ics   rq  mig lpa sysc us sy wa id   pc  %ec  lcs
...
  2    0    0    0   73    0    0    0    1 100    0  0  0  0 100 0.11  6.6   73
  3    0    0    0   42    0    0    0    1 100    0  0  0  0 100 0.11  6.6   42
...
  6    0    0    0   58    0    0    0    1 100    0  0  0  0 100 0.11  6.4   59
  7    0    0    0   79    0    0    0    1 100    0  0  0  0 100 0.11  6.4   79
ALL    0    0    0  812 106177  103    3  222 100 71183  3 48  0 49 1.69 337.9 40210
Here are 4 idle SMT threads - the processor as a whole is busy - so it counts as physc (pc column) but it is 100% idle. Basically, this is wasted "potential" and this is why the total %idle reported goes up. In the ST mode, these numbers are not counted, so it seems to be less idle.

So if you want to know how the virtual processor is idle, rather than just - on average "how much" you need the detailed output of a command like mpstat or sar -P.

Hope this helps!

Last edited by Michael AM; 09-07-2013 at 12:18 PM. Reason: change some QUOTE tags to CODE
 
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