GPA Manual for G-series RVUs

Guardian Performance Analyzer (GPA) Manual – (544977-001) Page 72 of 106
Example 4-15. Cache Performance Analysis for \NODEB
CACHE PERFORMANCE ANALYSIS
LOGICAL | ALLOCATED CACHE | CACHE HIT RATES(%) | REQUEST RATES
VOLUME | 512 1024 2048 4096 | 512 1024 2048 4096 | CACHE BLOCK/SECOND
| BLKS BLKS BLKS BLKS | | 512 1024 2048 4096
| | |
$SYSTEM | 16 30 10 50 | 99 99 66 87 | .2 1.4 .4
$PRODl | 180 6 7 30 | 96 99 46 | 3.2
$PROD4 | 8 6 6 63 | 90 83 | 14.0
$PROD3 | 8 380 10 73 | 78 76 77 77 | .1 .2 9.4
$TEST3 | 8 6 6 6 | 98 93 | .2 1.9
$PROD5 | 8 6 6 25 | 93 90 91 96 | 1.7
$PROD2 | 8 6 6 6 | 89 97 | .2
$TESTl
|
8 6 6 6
|
|
$TEST2 | 8 6 6 6 | 95 |
In the example, you can see that volumes $PROD4 and $PROD3, with request rates
of 14.0 and 9.7 per second for all cache blocks, account for most of the cache activity
on their respective primary processors, CPU 0 and CPU 2. The fact that the same two
volumes also exhibit poor cache performance, as indicated by the relatively low cache
hit rates for their blocks, shows that a reallocation of cache blocks would probably
improve the cache performance for the two volumes. The improved cache
performance should also bring down to acceptable levels the queue times for $PROD4
and $PROD3. On the basis of its cache performance analysis, GPA makes
recommendations for resetting cache allocations to improve performance.
Disk Subprocess Analysis and Recommendations
GPA generates an analysis of the disk subprocesses like the one shown in Example
4-16. This section of the standard report enables you to see the number of disk
subprocesses allocated to each logical disk volume. GPA makes recommendations to
add subprocesses when it finds that they are highly active. Making actual changes to
the number of disk subprocesses is done by performing a new SYSGEN or using SCF.
Before making these changes, you should double-check that the disk processing that
occurred during the measurement period is typical for your system. For example, you
might confirm that GPA shows the same recommendations over more than one 24-hour
measurement period where the disk processing appears to be typical.
The figure shows that all of the logical volumes in the system are configured with three
disk subprocesses (PINs) except $AUDIT, which has four. (The maximum that can be
configured is eight.) As you look at the figure, pay attention to the net change column.
This column shows the logical volumes for which GPA is making a recommended
change. In the case of $DATA, the net message rate on PIN#3 is quite high at over
3 messages/second. GPA therefore recommends that an additional PIN be allocated to
this logical volume. You can also see that $V80A2 has relatively low activity on its first
two PINs and no activity on its third. GPA recommends reconfiguring this logical
volume with one fewer PIN.