WLMTK Overview: Using HP-UX WLM Effectively With Your Most Critical Applications

Overview

WLMTK helps you capture the power of WLM. WLM is most powerful when managing CPU-bound

applications—it adjusts the CPU allocation of a group of processes known as a workload, basing

adjustment on the current needs and performance of the applications in that workload. A workload is

based on the collection of processes in:

• nPartitions that use Instant Capacity

• HP-UX virtual partitions

• Integrity VM hosts

• Resource partitions, which can be:

Whole-core: HP-UX pSets

Sub-core: Fair Share Scheduler (FSS) groups (WLM creates FSS groups using HP Process

Resource Manager (PRM))

Note

As of WLM A.03.01, PRM is no longer included with the WLM bundle. If

PRM C.03.00 or later is already on the machine on which you must install

or upgrade WLM, you can continue to manage FSS and pSet-based

workload groups (just as if PRM had been installed with WLM). If you are

installing WLM for the first time on a machine, you can use a strictly host-

based configuration (no pSet- or FSS-based workload groups). However, to

manage FSS and pSet-based workload groups, you must install PRM

(C.03.00 or later) separately.

To have WLM migrate resources among workloads as needed, you must define one or more SLOs in

the WLM configuration file for each workload. To define an SLO, you must specify its relative level of

importance (priority). WLM enables you to prioritize the SLOs so that an SLO assigned a high priority

has precedence over SLOs with a low priority. You can also specify a usage goal to attain a targeted

resource usage. If a performance measure (metric) is available, as is the case with most applications

discussed in this paper, you can specify a metric goal. As the applications run, WLM compares the

application usage or metrics against the goals. To achieve the goals, WLM automatically adjusts CPU

allocations for the workloads.

WLM allocates resources in “shares.” A CPU share represents 1/100 of a single core or 1/100 of

each core in the server, depending on the WLM mode of operation. If the default 100 shares are

available, each share is 1% of the system core.

Key uses of HP-UX WLM include:

• Using excess server capacity by consolidating multiple applications on fewer servers while ensuring

that mission-critical applications still get the resources they need during peak demand times

• Reallocating system resources automatically in response to changing priorities, conditions that

change over time (night/day, month-end processing, and so on), package movement in a cluster,

resource demand, and application performance

• Automating the deployment of reserve capacity so that customers pay only for what they need when

they need it

• Enabling higher utilization in clusters by enabling you to define, monitor, and enforce SLOs on a

server or partition that receives a failed-over workload