6. DATA SOURCES › 6.8 PR/SM LPAR Concepts › 6.8.5 Data Analysis › 6.8.5.2 LPAR Level Analysis › 6.8.5.2.1 General Purpose LPA/Rs › 6.8.5.2.1.2 z/OS LPARs With Specialized Processors
6.8.5.2.1.2 z/OS LPARs With Specialized Processors
Prior to the zAAP, CPU capacity tracking and planning for
z/OS dealt with only one processor type, the standard CP (or
general purpose) processor. With the introduction of the
zAAP and zIIP specialized processors, three types of
processors are used by z/OS, and separate sets of
measurements must be used to analyze LPAR utilization.
Three simple examples illustrate that traditional capacity
methods must be updated as soon as you include specialized
processors in your pool of CPU resources, in order to answer
the same questions always asked: How effectively are my CPU
resources used? Do I need more and which type?
Example 1
---------
Logical partition ZOS1 is configured with two standard CP
processors and one specialized processor. Last month, the
average utilization of each of these processors was:
CP Processor 1: 80%
CP Processor 2: 80%
Special Proc. : 20%
Using the traditional method, the average utilization of the
ZOS1 LPAR for the month would appear to be 60% (180%/3).
Does this information provide the answers to the previous
questions? Obviously not, since all the processors are
reported together, hiding the relatively important load of
the standard CPs compared to the low utilization of the
specialized processor. We cannot make any decision based on
such an overall perspective.
Now, using an updated method, we end up with two utilization
percentages, showing that the standard CPs were busy 80% of
the time, and the specialized processor only 20%. This is
much more valuable in regards to the important questions:
o How effectively are my CPU resources used?
This LPAR is correctly sized in terms of standard CP
processors. 80% busy means it really needs its two
standard CPs to handle the classical z/OS workload. On
the other hand the specialized processor is only used 20%
of the time. We can maximize its utilization either by
moving the eligible workload from other LPARs into ZOS1;
or even by removing the specialized processor from ZOS1
(the standard CPs might support the workload previously
only executed on this processor) and assigning it to
another LPAR. (This assumes the specialized processor is
executing at the same speed as the standard CP processors,
since the RMF records the CPU times at the physical engine
speed.)
o Do I need more CPU resources and which type?
With this current configuration, you know you can handle
an 80% increase in special workload, but only 20% in other
z/OS processing. Note that the 20% might be further
reduced if your data center allows special work to be
executed on both standard and specialized processors.
Example 2
---------
Logical partition ZOS2 is configured with two standard CP
processors and one specialized processor. Last month, the
average utilization of each of these processors was:
CP Processor 1: 30%
CP Processor 2: 30%
Special Proc. : 100%
Using the traditional method, the average utilization of the
ZOS2 LPAR for the month would appear to be 53% (160%/3).
Does this information provide the answers to the previous
questions? Here, again, we cannot make any decision based on
such combined information.
Now, using an updated method, we end up with two utilization
percentages, showing that the standard CPs were busy 30% of
the time, and the specialized processor 100%. A lot more
useful information would be as follows:
o How effectively are my CPU resources used?
This time, the LPAR is underutilizing its standard CP
processors because 30% busy means only one standard CP
would be sufficient to handle all classical z/OS workload.
On the other hand, the specialized processor is 100% busy.
We could not make any better profit of this low-cost
assistant.
o Do I need more CPU resources and which type?
In this configuration, the specialized processor cannot
accept any additional workload, but the standard CP
processors could support a 70% increase before reaching
their full capacity. Since, depending on the system
parameters, this extra capacity could be used by both
special and classical z/OS workload, a trade-off has to be
found between spending standard CP processor CPU cycles
for special work (and thus increasing the MSU consumption
of the LPAR), or adding a new low-cost specialized
processor. Performance is also a factor when a
specialized processor is too heavily loaded because
special work might be queued waiting for it while standard
CPs are available.
Example 3
---------
The two previous examples were intended to show you how
reporting solely at the overall LPAR level could be
misleading, but in a real configuration, you might have to
deal with LPARs where both types of processors are loaded in
a comparable way. This last example shows that the
information CA MICS obtains from PR/SM is not sufficient to
have a full understanding of such LPARs' utilization, and
that a complete analysis requires gathering additional
measurements from WLM at the workload level.
Logical partition ZOS3 is configured with two standard CP
processors and one specialized processor. Last month, the
average utilization of each of these processors was:
CP Processor 1: 90%
CP Processor 2: 90%
Special Proc. : 90%
Using the traditional method, the average utilization of the
ZOS3 LPAR for the month would appear to be 90% (270%/3).
This time, at least, this percentage tells us that there is
not much room left for additional workload. But, again it
does not answer the main capacity planning questions.
Let's assume the specialized processor is a zAAP. Not
surprisingly, using the updated method, we end up with two
similar utilization percentages, showing that both the
standard CPs and zAAP were busy 90% of the time. But, if we
know the zAAP can only be busy with Java work, we must
determine what is actually making the standard CPs so busy
too.
If the data center does not allow any Java work to run on
standard CPs, there is no doubt: these processors are busy
with non-Java work only, and as such, there is no way to
dispatch part of their workload to a zAAP, in order to reduce
their utilization. Therefore they might only support a 10%
load increase.
Things become more complex if Java work is allowed to execute
both on zAAP and standard CPs. Java work running on a
standard CP is called "zAAP eligible," and the CPU time
consumed by this type of work is not recorded separately in
the SMF type 70 subtype 1 record. RMF gathers this
information from the Workload Manager (WLM), and you must
retrieve it from the WLMSEC, Service Class Resource
Consumption file.
Suppose you determined that half of the CPU time consumed on
the standard CPs was attributable to zAAP eligible time. This
means that your 90% busy for the standard CPs is now
distributed as follows:
CP Processors Busy: 90%
Java Workload : 45%
non-Java Workload : 45%
With this information, it is now possible to evaluate the
potential solutions: for example, install a new zAAP; then
force Java work to run on zAAPs only; and finally, since the
standard CPs utilization has decreased to 45%, remove one of
them and reduce the LPAR MSU capacity.
Data Elements for Utilization Analysis
--------------------------------------
Below is a matrix of basic data elements you can use as a
starting point for dual standard CP and specialized processor
utilization analysis. Before using these elements, one
should keep in mind how they can be compared with each other.
For capacity studies, one should decide whether to base the
analysis on all of the processors for each type within the
complex or only on the processors that are online. If all of
the processors are online most of the time, then one would
probably want to base the analysis on all the processors. If
the number of online processors is less than the number of
available processors almost all of the time, then one would
likely base the analysis only on the online processors.
To base capacity analysis on all the processors, use the
elements LPCPCTSU, LPCPCTIU, LPCPCTZU, and LPCPCTDU. If you
need to restrict the study to online processors, then you
should use LPCPCVPU, LPCPCVIU, LPCPCVZU, and LPCPCVSU.
When an LPAR uses shared processors of any of the types CP,
zAAP, or zIIP and wait assist is disabled, then one would
expect that the percents of time the processors are busy as
reported by the CPUPCBSY, CPUPCBZP, or CPUPCBSU elements
would be the same as the corresponding percents based on
dispatch times as reported in the HARLPC file. Since
CPUPCBSY, CPUPCBZP, and CPUPCBSU are computed from busy time
divided by online time, the comparable elements from HARLPC
would be those that are computed by busy time divided by
online time. In this case, CPUPCBSY should have a value
close to LPCPCVPU; CPUPCBZP should have a value close to
LPCPCVZU; and CPUPCBSU should have a value close to LPCPCVSU.
Here is an example, showing how zIIP processor utilization is
tracked for an LPAR where three zIIP processors are defined
in the complex but only two are online during the measurement
interval. Therefore, the online time (LPCTSOTM) for the zIIP
processors is 30 minutes in a 15 minute RMF interval. The
value for CPUPCBSU and LPCPCVSU is 93.12% since both are
based on online time only. LPCPCTDU takes on the value
62.08% since it is based on the total number of zIIP
processors in the complex. Once again, the following
computations make sense only when the processors are shared
and wait assist is disabled.
LPCTSDTM = 0:27:56.24
LPCTSOTM = 0:30:00.00
DURATION = 0:15:00.00
PRSMTSP = 3
CPUPCBSU = 0:27:56.24 / 0:30:00.00 = 93.12 %
LPCPCVSU = 0:27:56.24 / 0:30:00.00 = 93.12 %
LPCPCTDU = 0:27:56.24 / (0:15:00.00 * 3) = 62.08 %
+----------+------------------------------------------------+
! File: ! HARCPU - CPU Activity File !
! ! !
+==========+================================================+
! Element ! Label !
+----------+------------------------------------------------+
! CPUAVONL ! Avg Number of Online CP Processors !
! CPUAVOZP ! Avg Number of Online zAAP Processors !
! CPUAVOSU ! Avg Number of Online zIIP Processors !
+----------+------------------------------------------------+
! CPUPCBSY ! Pct CP Processors Busy !
! CPUPCBZP ! Pct zAAP Processors Busy !
! CPUPCBSU ! Pct zIIP Processors Busy !
+----------+------------------------------------------------+
! CPUPCTDT ! Pct CP Proc. Dispatched - Effective !
! CPUPCTDZ ! Pct zAAP Proc. Dispatched - Effective !
! CPUPCTDS ! Pct zIIP Proc. Dispatched - Effective !
+----------+------------------------------------------------+
! CPUTOBTM ! Total Time CP Processors Busy !
! CPUZPBTM ! Total Time zAAP Processors Busy !
! CPUSUBTM ! Total Time zIIP Processors Busy !
+----------+------------------------------------------------+
! CPUTODTM ! Total CP Processors Dispatch Time !
! CPUZPDTM ! Total zAAP Processors Dispatch Time !
! CPUSUDTM ! Total zIIP Processors Dispatch Time !
+----------+------------------------------------------------+
! CPUTOOTM ! Total CP Processors Online Time !
! CPUZPOTM ! Total zAAP Processors Online Time !
! CPUSUOTM ! Total zIIP Processors Online Time !
+----------+------------------------------------------------+
+----------+------------------------------------------------+
! File: ! HARLPC - PR/SM LPAR Config/Activity File !
! ! !
+==========+================================================+
! Element ! Label !
+----------+------------------------------------------------+
! LPCAVCPU ! Avg Number of Active CP Processors !
! LPCAVICF ! Avg Number of Active ICF Processors (zSeries) !
! LPCAVZAP ! Avg Number of Active zAAP Processors (z9) !
! LPCAVSUP ! Avg Number of Active zIIP Processors (z9) !
+----------+------------------------------------------------+
! LPCPCSSU ! LPAR Shared CP Processors Utilization !
! LPCPCSIU ! LPAR Shared ICF Procs. Utilization (zSeries) !
! LPCPCSZU ! LPAR Shared zAAP Procs. Utilization (z9) !
! LPCPCSDU ! LPAR Shared zIIP Procs. Utilization (z9) !
+----------+------------------------------------------------+
! LPCPCTSU ! LPAR Total CP Processors Utilization !
! LPCPCTIU ! LPAR Total ICF Processors Utilization (zSeries)!
! LPCPCTZU ! LPAR Total zAAP Processors Utilization (z9) !
! LPCPCTDU ! LPAR Total zIIP Processors Utilization (z9) !
+----------+------------------------------------------------+
! LPCPCVPU ! LPAR CP Processors Utilization !
! LPCPCVIU ! LPAR ICF Processors Utilization (zSeries) !
! LPCPCVZU ! LPAR zAAP Processors Utilization (z9) !
! LPCPCVSU ! LPAR zIIP Processors Utilization (z9) !
+----------+------------------------------------------------+
! LPCTODTM ! Total CP Processors Dispatch Time !
! LPCTIDTM ! Total ICF Processors Dispatch Time (zSeries) !
! LPCTZDTM ! Total zAAP Processors Dispatch Time (z9) !
! LPCTSDTM ! Total zIIP Processors Dispatch Time (z9) !
+----------+------------------------------------------------+
! LPCTOEDT ! Total CP Proc. Effective Dispatch Time !
! LPCTIEDT ! Total ICF Proc. Effective Dispatch Tm (zSeries)!
! LPCTZEDT ! Total zAAP Proc. Effective Dispatch Time (z9) !
! LPCTSEDT ! Total zIIP Proc. Effective Dispatch Time (z9) !
+----------+------------------------------------------------+
! LPCTOOTM ! Total CP Processors Online Time !
! LPCTIOTM ! Total ICF Processors Online Time (zSeries) !
! LPCTZOTM ! Total zAAP Processors Online Time (z9) !
! LPCTSOTM ! Total zIIP Processors Online Time (z9) !
+----------+------------------------------------------------+
+----------+------------------------------------------------+
! File: !WLMSEC - Service Class Resource Consumption +
! ! !
+==========+================================================+
! Element ! Label !
+----------+------------------------------------------------+
! WLMZAPNF ! zAAP Service Time Normalization Factor !
! WLMSUPNF ! zIIP Service Time Normalization Factor !
+----------+------------------------------------------------+
! SECCPUTM ! CPU Time on CP !
! SECZAPTM ! CPU Time on zAAP (Normalized) !
! SECSUPTM ! CPU Time on zIIP (Normalized) !
! SECZAPCT ! zAAP Eligible CPU Time on CP !
! SECSUPCT ! zIIP Eligible CPU Time on CP !
! SECZAPUT ! Un-normalized zAAP CPU Time !
! SECSUPUT ! Un-normalized zIIP CPU Time !
+----------+------------------------------------------------+
! SECTOCPU ! CPU Service Units on CP !
! SECTOZAP ! CPU Service Units on zAAP !
! SECTOSUP ! CPU Service Units on zIIP !
! SECTZAPC ! zAAP Eligible CPU Service Units on CP !
! SECTSUPC ! zIIP Eligible CPU Service Units on CP !
+----------+------------------------------------------------+
+----------+------------------------------------------------+
! File: ! WLMSDE - Service Definition !
! ! !
+==========+================================================+
! Element ! Label !
+----------+------------------------------------------------+
! SDEIFAHO ! Intvls with IFAHonorPriority !
+----------+------------------------------------------------+
! SDEIFAXO ! Intvls with IFACrossOver !
+----------+------------------------------------------------+
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