IBM Z10 EC User Manual download pdf (Page 33)

A solution is HiperSockets Multiple Write Facility.

HiperSockets performance has been enhanced to allow

for the streaming of bulk data over a HiperSockets link

between logical partitions (LPARs). The receiving LPAR

can now process a much larger amount of data per I/O

interrupt. This enhancement is transparent to the operating

system in the receiving LPAR. HiperSockets Multiple Write

Facility, with fewer I/O interrupts, is designed to reduce

CPU utilization of the sending and receiving LPAR.

The HiperSockets Multiple Write solution moves multiple

output data buffers in one write operation.

If the function is disabled then one output data buffer

is moved in one write operation. This is also how

HiperSockets functioned in the past.

If the function is enabled then multiple output data buf-

fers are moved in one write operation. This reduces CPU

utilization related to large outbound messages. When

enabled, HiperSockets Multiple Write will be used anytime

a message spans an IQD frame requiring multiple output

data buffers (SBALs) to transfer the message. Spanning

multiple output data buffers can be affected by a number

of factors including:

• IQD frame size

• Application socket send size

• TCP send size

• MTU size

The HiperSockets Multiple Write Facility is supported in

the z/OS environment. For a complete description of the

System z10 connectivity capabilities refer to IBM System z

Connectivity Handbook, SG24-5444.

HiperSockets Enhancement for zIIP Exploitation

In z/OS V1.10, speciﬁ cally, the z/OS Communications

Server allows the HiperSockets Multiple Write Facility

processing for outbound large messages originating

from z/OS to be performed on a zIIP. The combination of

HiperSockets Multiple Write Facility and zIIP enablement

is described as “zIIP-Assisted HiperSockets for large mes-

sages.” zIIP-Assisted HiperSockets can help make highly

secure, available, virtual HiperSockets networking a more

attractive option. z/OS application workloads based on

XML, HTTP, SOAP, Java, etc., as well as traditional ﬁ le

transfer, can beneﬁ t from zIIP enablement by helping to

lower general purpose processor utilization for such TCP/

IP trafﬁ c.

Only outbound z/OS TCP/IP large messages which origi-

nate within a z/OS host are eligible for HiperSockets zIIP-

Assisted processing. Other types of network trafﬁ c such

as IP forwarding, Sysplex Distributor, inbound processing,

small messages, or other non TCP/IP network protocols

are not eligible for zIIP-Assisted HiperSockets. When the

workload is eligible, then the TCP/IP HiperSockets device

driver layer (write) processing is redirected to a zIIP,

which will unblock the sending application. zIIP-Assisted

HiperSockets for large messages is available with z/OS

V1.10 with PTF and System z10 only. This feature is unsup-

ported if z/OS is running as a guest in a z/VM environment

and is supported for large outbound messages only.

To estimate potential ofﬂ oad, use PROJECTCPU for current

and existing workloads. This is accurate and very simple,

but you have to be on z/OS 1.10 with the enabling PTFs

AND System z10 server AND you need to be performing

HiperSockets Multiple Write workload already on z/OS.

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