The Variable Correlation Screen (FCX194) provides
a quick overview showing how well any of the many performance variables saved
in the HISTLOG and HISTSUM history files correlates with a selected base variable.
Figure 1. Layout of Variable
Correlation Screen (FCX194)
FCX194 Input File: 'yyyymmdd HISTLOG *' Perf. Monitor
Correl. Coefficients for Base Variable CPU (% total CPU , 165 Samp)
Selection: From (not set) Days : All days
To (not set) Hours: All hours
Corre- Variable Variable Corre- Variable Variable
lation Name Description lation Name Description 1.000 %LogLd % logical CPU 1.000 %US % user CPU
.997 %EM % emulation CPU .957 VMStl VMDBK steal rate
.953 %CP % supervisor CPU .950 XAl/s XSTORE alloc/s
.948 XSStl/s XSTORE steals/s .946 XSDel/s XSTORE delete/s
.940 %SY % system CPU .938 XDeal/s XSTORE dealloc/s
.928 DIAG DIAG instr./s .926 Alo/s Page alloc. rate
.920 SIE SIE instr. rate .920 PRIV Inst. simul./s
.911 SIEIC SIE intercept/s .907 Dsptch Users dispatched
.899 VMCF>C VMCF rate to CP .899 VMCF>V VMCF rate to VM
.899 VMCF_T Total VMCF rate .898 VRecv User VMCF recv/s
.898 VSend User VMCF send/s .896 NT-Q Non-triv. queue
.896 PGOUT/s PAGOUT rate/s .895 Scan1 Scan 1 rate
.895 MDUS MDC insert users .892 TR-Q Trivial queue
.892 ExtInt Ext. interrupt/s .892 XPg/s XSTORE page rate
Select new base variable to recompute
Command ===> _
F1=Help F4=Top F5=Bot F7=Bkwd F8=Fwd F12=Return
A good correlation with the base variable is indicated by highlighting the entry.
The correlation coefficient is shown in:
Yellow
For correlation coefficients of 0.9 to 1.0.
White
For correlation coefficients of 0.8 to 0.9.
Green
For all other values.
The sample shows a screen with correlations for base variable CPU (total CPU load), the default.
You can select any other base variable by performing on of these actions"
Specifying the variable name with the CORREL subcommand when
selecting the screen.
Moving the cursor to any variable on the correlation display and
then pressing ENTER.
Field Descriptions:
General Header Lines:
Correl. Coefficients for Base Variable CPU
This line shows which variable was used as a "base" variable against
which the correlation coefficients for all other variables were calculated.
Selection
Shows the criteria applied when selecting performance data from the
history file. Record selection can be based on an overall period (From and To specifications) and can be restricted to a smaller
subset by selecting only specific days and/or hours.
From
Shows the start date or time of a selected period, or (not set) when no start date and time have been specified.
To
Shows the end date or time of a selected period, or (not set) when
no end dateand time have been specified.
Days
Shows for which weekdays history log records have been processed.
Hours
Shows for which hours history log records have been processed.
Correlation
The correlation coefficient for the variable.
The correlation will be shown as a number between -1.0 and +1.0, with the following exceptions:
*ZERO*
Indicates that all of the values processed were 0.
*CONS*
Indicates that all of the values were the same, that is, the variable was
a constant during the selected period.
Dots indicate that an insufficient number of valid measurements was found
to allow calculation of a meaningful correlation.
Variable Name
The variable name, as described for the REDHIST display. (See REDHIST.)
A question mark in front of the variable name indicates
correlation factors of questionable validity because the number of samples
for the variable was less than 1/4 of the number of samples for the base variable,
as indicated in the header line.
Variable Description
A short description of the variable. See the corresponding paragraphs
for the REDHIST display (REDHIST) for a more detailed description.
Effect of 'AVERAGE' and 'INTERIM'
subcommands: None.