Intel AS/400 RISC Server Manual de usuario descargar pdf (Pagina 322)

HMT and SMT Compared and Contrasted

Some key similarities and differences are:

ySMT can improve throughput up to 40 per cent,

in rare cases, higher.

yHMT typically improves throughput by 10 to 25

per cent.

ySMT can allow QPRCMLTTSK to change at any

time.

yHMT needs a full IPL for the change to

QPRCMLTTSK to be activated.

ySMT has three values for QPRCMLTTSK ("0"

for off, also called "ST mode", "1" for on, and "2"

for "controlled" where OS/400 decides,

dynamically, whether to be in ST or SMT mode.

yHMT operation is controlled by the system value

QPRCMLTTSK ("1" means active, "0" means

inactive)

ySMT machines continue to report data on a

physical processor basis, but some of the

measurements are harder to interpret (reporting on

a logical CPU basis would be no better).

ySystem performance counters and CPU

utilization values continue to be reported on a

physical CPU basis.

ySMT complicates the question of measuring

CPU utilization.

yCPU utilization measurements are not greatly

affected by HMT.

ySMT allows multiple streams of execution

simultaneously.

yHMT executes only one instruction stream at a

time.

ySMT, because it is more dynamic, the SMT state

need not be identical across partitions.

yAll partitions have the same value for HMT

ySMT can be turned on and off dynamically at

any time. No IPL required

yHMT is can be turned on and off only by a

whole system IPL.

SMT FeatureHMT Feature

Models With/Without HMT

Not all prior models have HMT. In fact, some recent models have neither HMT nor SMT.

The following models have HMT available:

y 270, 800, 810, 820, 830, 840

The following have neither SMT nor HMT:

y 825, 870, 890

Earlier models than the 270 or 820 series (e.g. 170, 7xx, etc.) did not have either HMT nor SMT.

IBM i 6.1 Performance Capabilities Reference - January/April/October 2008

1 2 ... 317 318 319 320 321 322 323 324 325 326 327 ... 367 368

Comentarios a estos manuales

Sin comentarios

Intel AS/400 RISC Server Manual de usuario Pagina 322

Comentarios a estos manuales