6.7

Table 1‑92. CPU Performance Enhancement Advice (Continued)
# Resolution
3 Compare the CPU usage value of a virtual machine with the CPU usage of other virtual machines on the host or in the
resource pool. The stacked line chart on the host's Virtual Machine view shows the CPU usage for virtual machines on the
host.
4 Determine whether the high ready time for the virtual machine resulted from its CPU usage time reaching the CPU limit
setting. If so, increase the CPU limit on the virtual machine.
5 Increase the CPU shares to give the virtual machine more opportunities to run. The total ready time on the host might remain
at the same level if the host system is constrained by CPU. If the host ready time doesn't decrease, set the CPU reservations
for high-priority virtual machines to guarantee that they receive the required CPU cycles.
6 Increase the amount of memory allocated to the virtual machine. This decreases disk and or network activity for applications
that cache. This might lower disk I/O and reduce the need for the host to virtualize the hardware. Virtual machines with
smaller resource allocations generally accumulate more CPU ready time.
7 Reduce the number of virtual CPUs on a virtual machine to only the number required to execute the workload. For example, a
single-threaded application on a four-way virtual machine only benefits from a single vCPU. But the hypervisor's maintenance
of the three idle vCPUs takes CPU cycles that could be used for other work.
8 If the host is not already in a DRS cluster, add it to one. If the host is in a DRS cluster, increase the number of hosts and
migrate one or more virtual machines onto the new host.
9 Upgrade the physical CPUs or cores on the host if necessary.
10 Use the newest version of hypervisor software, and enable CPU-saving features such as TCP Segmentation Offload, large
memory pages, and jumbo frames.
Memory (MB)
The Memory (MB) chart displays memory usage in the vApp or resource pool.
This chart is located in the Home view of the vApp or resource pool Performance tab.
Table 1‑93. Data Counters
Chart Label Description
resource_pool or vApp Sum of the active memory used by all virtual machines in the resource pool or vApp. Active memory is
determined by the VMkernel and includes overhead memory.
memory usage = active memory / configured virtual machine memory size
n
Counter: used
n
Stats Type: Absolute
n
Unit: Megabytes (MB)
n
Rollup Type: Average
n
Collection Level: 1
Chart Analysis
Memory usage is not an indicator of performance problems. Memory can be high if a host is swapping or
ballooning, which can result in virtual machine guest swapping. In such cases, check for other problems,
such as CPU over-commitment or storage latencies.
If you have constantly high memory usage in a cluster, resource pool, or vApp, consider taking the
following actions.
vSphere Monitoring and Performance
VMware, Inc. 75