HP-UX vPars and Integrity VM V6.3 Administrator Guide

3.1.1 VSP pool
The CPU cores in the VSP pool run normal VSP processes. In addition, the cores run special threads
to service I/O requests for vPars and Integrity VM. These cores cannot be used for vPars and VM
guest configurations.
By default, there are no cores in the VSP pool. When you configure the first reserved vPar or when
you start the first non-reserved vPar, a single core is added to this pool. If vPar configurations exist
(for example, after upgrading an existing vPars V6.0 system), the cores reserved for VSP is non-zero.
If the configuration does not contain any vPars (for example, after upgrading an existing Integrity
VM V4.3 system), the cores reserved for the VSP is zero, matching the Integrity VM Host in a
Integrity VM V4.3 environment.
A single VSP core can service moderate to heavy I/O loads and vPars management requests. You
can use performance tools such as glance and top to determine the CPU utilization of the VSP.
When the VSP core becomes saturated, the response time of vPars commands and other applications
on the VSP might increase. In such a situation, use the hpvmhwmgmt or vparhwmgmt command
to add more cores to the VSP pool.
The sum of vPar cores, VM cores (when you consider the VCPU entitlements) and VSP cores cannot
exceed the total number of cores on the system. While adjusting the VSP core count, if you exceed
the system core count, and if the vPars and Integrity VMs are already configured, an error occurs.
In such a situation, to meet the required core count for the VSP, first adjust the core count of one
or more vPars and VM guests using the hpvmmodify or vparmodify command. Then, adjust
the VSP CPU core count using the hpvmhwmgmt or vparhwmgmt command.
IMPORTANT: If the system is brought down due to a faulty CPU core and the cores are
deconfigured, then the vPars and Integrity VMs might not boot during the subsequent boot of the
VSP. This is possible if the sum of the remaining cores is less than the sum of the cores allocated
to the VSP, vPars and Integrity VMs as displayed by the hpvmhwmgmt or vparhwmgmt command.
Fix this by removing the cores from the vPars and Integrity VM or VSP, or even by reducing the
overall CPU entitlement for one or more VMs to meet the configuration requirements.
3.1.2 vPars and Integrity VM pool
These cores are available for vPars and Integrity VMs. By default, all the cores on the VSP will be
in this pool. As mentioned, when the first reserved vPars is configured or when the first non-reserved
vPars is started, a single core is moved from this pool to the VSP pool. When reserved vPars are
configured on the VSP, cores are reserved from this pool. When the vPars instances are initiated,
the reserved cores are removed from this pool and assigned to the particular vPars.
3.2 Hyperthreading on the VSP
By default, VSP has the hyperthreading (firmware setting) set to ON in the npartition or server;
and HP-UX kernel tunable lcpu_attr set to OFF in the VSP. This setting enables optimal
performance and responsiveness of the VSP. DO NOT change the default hyperthreading settings
in the VSP, unless it is recommended in the documentation.
NOTE: Hyperthreading is not supported for Integrity VM.
Hyperthreading is supported in individual vPars. To verify whether hyperthreading is enabled in
an individual vPars, use the setboot command.
If hyperthreading is enabled, it shows that HT is ON.
To turn on lcpu_attr in an individual vPars, use the kctune command.
By default, lcpu_attr is OFF in the vPars.
NOTE: Even when lcpu_attr is OFF in the VSP, each vPars can have its individual lcpu_attr
enabled to get hyperthreading functionality in the vPars.
38 Configuring VSP