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imposes some type of constraint, tuning often becomes a balancing act, trading off
the needs of the whole system against the needs of specific virtual machines.
Sometimes providing more resources to one virtual machine is detrimental to other
virtual machines or to the system as a whole. For instance, you might not want
virtual machines used for testing programs to get as much system resources as
production virtual machines, because your objective is to give production work
maximum throughput. Performance monitoring can help you understand which
changes meet your performance objectives.
You can use the INDICATE command (class B, C, and E users) to obtain an
informal snapshot of system load, scheduler dispatcher queues, and I/O. The
QUERY SHARE command (class A and E) allows you to view the share of system
resources a virtual machine has. Both of these commands provide only a snapshot,
while the MONITOR command collects large amounts of performance
measurement data for later systematic and comprehensive analysis.
The MONITOR command (class A and E users) starts and stops the emission of
data relevant to specific system events. The command also starts and stops the
collection, and periodic emission, of sample data descriptive of system
performance.
Monitor domains divide the emitted data into topic areas: behavior of I/O, behavior
of the scheduler, configuration of the z/VM system, settings of the monitor itself,
and so on. Data the monitor emits under a certain domain includes both event
information (such as a user logoff) and sample information (collected performance
measurement data, usually counters).
Monitoring Linux virtual servers with Performance Toolkit for
VM
z/VM provides analysis tools, such as Performance Toolkit for VM, that helps you
analyze the data you collect with the MONITOR command. In addition to
analyzing z/VM performance data, Performance Toolkit for VM processes Linux
performance data, provided you have the proper support software. To process
Linux performance data, you have these choices:
v Install a commercial Linux on a system that contains a mainframe performance
v Use a Linux 2.6 kernel such as SLES9, which has built-in support that allows
v For additional performance data from Linux, install RMF
Related information
v For more about z/VM performance, see z/VM: Performance, SC24-6208.
v For more about Performance Toolkit for VM, see z/VM: Performance Toolkit
Overview of the z/VM scheduler
This topic gives a rudimentary introduction to the z/VM scheduler so you can
understand system responses to commands such as INDICATE.
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z/VM: Getting Started with Linux on System z
monitoring product.
Performance Toolkit for VM to monitor Linux virtual servers.
and configure Performance Toolkit for VM to access this data.
Note: The RMF Performance Monitor is produced by an IBM Technical Study
and is not a part of any IBM product.
Reference, SC24-6210.
™
Performance Monitor
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