Performance statistics for shared memory

The Hardware Management Console (HMC) and Linux® environments provide statistics about the shared memory configuration.

Where to view statistics Statistics to view
HMC utilization data
  • Statistics about the shared memory pool, such as:
    • Size of the shared memory pool
    • Total amount of memory that is over committed
    • Total amount of logical memory that is assigned to the shared memory partitions
    • Total amount of I/O entitled memory that is assigned to the shared memory partitions
    • Total amount of physical memory that the shared memory partitions currently use for their I/O devices
    • Amount of memory from the shared memory pool that the hypervisor uses to manage the shared memory partitions
    • The time it takes, in microseconds, for data to be written to the shared memory pool from the paging space device
  • Statistics about the shared memory partitions, such as:
    • Amount of logical memory assigned to the shared memory partition
    • Amount of physical memory from the shared memory pool that is allocated to the shared memory partition
    • Amount of memory that is over committed
    • I/O entitled memory assigned to the shared memory partition
    • Amount of physical memory that the shared memory partition currently uses for its I/O devices
    • Memory weight of the shared memory partition
IBM® i

See IBM® i to view shared memory statistics in IBM i.

  • Statistics about the shared memory pool, such as:
    • Total number of page faults for all of the shared memory partitions
    • Total time, in milliseconds, that the processors waited for page faults to be resolved
    • Total physical memory, in bytes, that is assigned to the shared memory pool
    • Sum of the logical memory, in bytes, that is assigned to all of the shared memory partitions that are active
    • Sum of the I/O entitled memory, in bytes, that is assigned to all of the shared memory partitions that are active
    • Sum of the physical memory, in bytes, that the shared memory partitions that are active currently use for their I/O devices
  • Statistics about the shared memory partition, such as:
    • Memory weight of the shared memory partition
    • Amount of physical memory, in bytes, from the shared memory pool that is currently used by the shared memory partition
    • Number of times that the shared memory partition waited for a page fault
    • The time, in milliseconds, that the shared memory partition waited for page faults to be resolved
    • Maximum amount of memory, in bytes, that the shared memory partition can assign to data areas that are shared between the operating system and the server firmware
    • I/O entitled memory assigned to the shared memory partition
    • Minimum amount of physical memory, in bytes, required for all of the configured I/O devices to operate
    • Optimal amount of physical memory, in bytes, required for I/O devices to maximize throughput performance
    • Amount of physical memory, in bytes, that the shared memory partition currently uses for its I/O devices
    • Highest amount of physical memory, in bytes, that the shared memory partition has used for its I/O devices since the last time the shared memory partition was activated or since the last time the memory statistics were reset, whichever is most recent
    • Number of delayed I/O operations since the last time the shared memory partition was activated
Linux

View memory statistics for Linux in the sysfs file system as follows:

  • Shared memory partition data: cat /proc/ppc64/lparcfg
  • Virtual I/O bus attributes: /sys/bus/vio/ directory.
  • Virtual I/O device attributes: /sys/bus/vio/devices/ directory. This directory has a subdirectory for each device. Look in the subdirectory for each device to see the virtual I/O device statistics for each device.
  • Shared Memory statistics: amsstat (included in powerpc-utils)
  • Shared Memory graphical monitoring: amsvis (included in powerpc-utils-python)
  • Statistics about the shared memory partition:
    • I/O entitled memory set for the shared memory partition
    • Memory weight of the shared memory partition
    • Amount of physical memory allocated to the shared memory partition
    • Size of the shared memory pool to which the shared memory partition belongs
    • Frequency that data is written to the shared memory pool from the paging space device
    • The time it takes, in microseconds, for data to be written to the shared memory pool from the paging space device
  • Statistics about the virtual I/O bus, such as the highest amount of physical memory the shared memory partition has ever used for its I/O devices.
  • Statistics about the virtual I/O devices, such as the frequency that the device tried to map a page to perform an I/O operation and was unable to obtain sufficient memory. In this situation, the attempt fails and delays the I/O operation.
  • Statistics about the tools:
    • The packages powerpc-utils and powerpc-utils-python are user space packages.
    • The amsstat script can be run from a Linux logical partition to display shared memory statistics associated with the logical partition.
    • The amsvis tool is a python based graphical tool that displays similar information in a graphical manner. This tool is capable of aggregating data from multiple Linux shared memory logical partitions to obtain a picture of cross logical partition performance of shared memory Linux logical partitions.