IBM eServer zSeries 990 Technical Guide

Chapter 8. Capacity upgrades 223

The PCIXCC feature supports secure cryptographic functions, use of secure encrypted key

values, and User-Defined Extensions.

Continued cryptographic support for the e-business environment

PCI Cryptographic Accelerator (PCICA) FC 0862 is also available on the z990. This

hardware-based cryptographic solution continues to address the high Secure Sockets Layer

(SSL) performance needs of the on demand environment.

The SSL and Transport Layer Security (TLS) protocols are essential and widely used

protocols to support secure e-business applications. Compute-intensive public key

cryptographic processes that use SSL/TLS can be offloaded from the host to the PCICA

feature to reduce CP and IFL usage, thus increasing system throughput.

Performance assists for Linux and z/VM

򐂰 z990 adapter interruptions for Linux and z/VM: The z990, Linux on zSeries, and z/VM

work together to provide performance improvements by exploiting extensions to the

Queued Direct Input/Output (QDIO) architecture. Adapter interruptions, first added to

z/Architecture with HiperSockets, provide an efficient, high-performance technique for I/O

interruptions to reduce path lengths and overhead in both the host operating system and

the adapter: FICON Express when using the FCP CHPID type, and OSA-Express when

using the OSD CHPID type.

In extending the use of adapter interruptions to FCP and OSD (QDIO) channels, the

programming overhead to process a traditional I/O interruption is reduced. This benefits

OSA-Express TCP/IP support in both Linux on zSeries and z/VM, and FCP support in

Linux on zSeries.

Adapter interruptions apply to a z990 FICON Express channel when in FCP mode (FCP

CHPID type), which supports attachment of SCSI devices in a Linux on zSeries

environment. This support is exclusive to z990 and applies to all of the OSA-Express

features available on z990, when in QDIO mode (OSD CHPID type).

򐂰 Performance assist for V=V guests in the z/VM environment: z990's support of virtual

machine technology has been enhanced to include a new performance assist for

virtualization of Adapter Interruptions. This new z990 performance assist is available to

V=V guests (only pageable guests) that support QDIO (Queued Direct Input/Output) on

z/VM V4.4 and later. The deployment of adapter interruptions improves efficiency and

performance by reducing overhead.

The z990 performance assist for V=V guests is a passthrough architecture that reduces

host programming overhead by avoiding the need to stop guest processing when adapter

interruptions are presented. Without the assist, the z/VM control program must intercede

to process and route the adapter interruptions.

The z990 performance assist improves Linux on zSeries performance under z/VM by

allowing guest I/O (FICON (FCP CHPID type), HiperSockets (IQD CHPID type), and

OSA-Express (OSD CHPID type)) to be handled with minimal z/VM overhead through

direct presentation of adapter interruptions by the server to a pageable guest, boosting I/O

performance.

8.8 Capacity measurements

The result of all performance related characteristics of a server should be evaluated by their

combined effect when estimating the system performance. Some design and/or

implementation aspects can improve the performance of specific workloads and this should

also be evaluated.