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Summary of Key Findings

This section summarizes the performance evaluation of z/VM 4.1.0. For further information on any given topic, refer to the page indicated in parentheses.

Performance Changes 

z/VM 4.1.0 includes a number of performance enhancements (see Performance Improvements). In addition, some changes were made that affect VM performance management (see Performance Management):

  • Performance Improvements
    • Fast CCW Translation for Network I/O
    • Enhanced Guest Page Fault Handling
    • CMSINST Shared Segment Addition

  • Performance Management Changes
    • Monitor Enhancements
    • Effects on Accounting Data
    • VM Performance Products

Migration from z/VM 4.1.0 

Regression measurements for the CMS environment (CMS1 workload) and the VSE guest environment (DYNAPACE workload) indicate that the performance of z/VM 4.1.0 is equivalent to z/VM 3.1.0 and that the performance of TCP/IP Level 410 is equivalent to TCP/IP Level 3A0.

New Functions 

The fast CCW translation extensions improve the efficiency of network I/O issued by guest operating systems. Measurement results for a Linux guest show a 39% decrease in CP CPU time for I/O to an LAN Channel Station (LCS) adapter and a 44% decrease in CP CPU time for I/O to a real CTC adapter (see Fast CCW Translation for Network I/O).

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