Chapter 1. Performance Toolkit for VM at a glance 17
Figure 1-11 FCONTROL BENCHMRK subcommand syntax
Command options define:
Query Displays devices and users currently being benchmarked.
DEVice xxxx I/O device to benchmark.
USEr userid User to be benchmarked.
FILe Benchmarking data is logged to disk.
hh:mm to hh:mm The respective start and end times to monitor.
OFF Disables benchmarking for the specified device or user.
1.10 Threshold monitoring
With Performance Toolkit for VM, it is possible to set thresholds for some key
performance variables. This generates alert messages when the limit value is
exceeded. Due to the complexity of large systems, a single value for a threshold
is often not enough to determine whether a performance problem exists.
Therefore, the threshold function of Performance Toolkit for VM enables you to
define some additional parameters as prerequisites to make it more likely that an
alert message will be generated only when a performance problem really exists.
Dev or User
Dev or User
18 Linux on IBM Eserver zSeries and S/390: Performance Toolkit for VM
Threshold monitoring is controlled using the FCONTROL LIMIT subcommand.
Figure 1-12 shows the command syntax.
Figure 1-12 FCONTROL LIMIT subcommand syntax
Performance values that can be used for threshold monitoring include:
All performance variables that are included in the HISTLOG/HISTSUM
performance history log files. For a complete list, see z/VM: Performance
Normalized CPU load (NORMCPU) and normalized logical CPU load
Device I/O request queue length (DVQUEUE).
Device I/O response time (DVRESP).
Missing interrupts for I/O devices.
Channel busy percentage (%CHBUSY).
In addition to the actual threshold value, you can also define:
The minimum amount of users expected in queue for class 1 (q1) and the
total in-queue users for the classes 0, 2, and 3 (qx).
Chapter 1. Performance Toolkit for VM at a glance 19
The time period in minutes that a problem must exist before a message is
generated. You can specify a time interval use to repeat the message if the
problem still exists.
The combination of these thresholds helps separate short peaks from real
performance problems that need investigation. Figure 1-13 shows an example of
different alert messages that are generated by threshold settings.
Figure 1-13 Alert messages generated by threshold settings
Alert messages are highlighted and do not automatically scroll. You can delete
alert messages using the DELETE subcommand followed by the line number.
(For example, to delete message lines 23 through 30, use the DEL 23-30
Note: An exceeded threshold is considered to be a problem only if both the
q1 and the qx user count are at least as high as the specified minimum. For
more detailed information, see 5.4, “System settings” on page 109.
FCX001 -------------- Press 'ENTER' to continue -------------- Autoscroll 12
+23 08:37:00 FCXPER315A Cl1 time slice 2.002 exceeds limit 1.000 (Q1=01 Qx=02)
+24 08:59:00 FCXUSL317A User LNXSU1 IO/s 377 exceeded threshold 50.0 for 5 min.
+25 09:51:00 FCXUST457A PERFKLA 60% active: may need higher priority
+26 10:12:00 FCXPER315A % I/O wait (sys) 52 exceeds limit 50 (LNXRH1 .5 IO/S)
+27 10:27:00 FCXPER315A Cl1 time slice 2.002 exceeds limit 1.000 (Q1=01 Qx=03)
+28 10:27:00 FCXPER315A % I/O wait (sys) 52 exceeds limit 50 (PERFROG .5 IO/S)
*29 12:00:00 MSG FROM PERFKLA : IT IS NOW 12:00H
+30 12:32:00 FCXPER315A Cl1 time slice 2.000 exceeds limit 1.000 (Q1=01 Qx=02)
+31 12:32:00 FCXPER315A % I/O wait (sys) 55 exceeds limit 50 (PERFROG .6 IO/S)
+32 12:39:00 FCXPER315A Cl1 time slice 2.002 exceeds limit 1.000 (Q1=01 Qx=03)
+33 12:50:00 FCXCHA318A Channel 48: 67% busy exceeds limit of 40%
+34 13:03:00 FCXCHA318A Channel 49: 70% busy exceeds limit of 40%
+35 14:28:00 FCXCHA318A Channel 75: 70% busy exceeds limit of 40%
+36 14:39:00 FCXUSL317A User LNXSU2 IO/s 574 exceeded threshold 50.0 for 5 min.
+37 14:49:00 FCXUSL317A User LNXSU1 %CPU 33.9 exceeded threshold 30.0 for 5 min.
+38 14:59:00 FCXUSL317A User LNXSU1 %CPU 56.7 exceeded threshold 30.0 for 15 min.
+38 15:09:00 FCXUSL317A User LNXSU1 %CPU 37.1 exceeded threshold 30.0 for 25 min.
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