HP VMA-series Memory Arrays Manual do Utilizador descarregar pdf (Página 175)

Network-Layer Performance Testing

HP-AM456-9002A Rev 01

VMA-series Memory Array Installation and Service Guide

175

The following table describes the options used in this command. For a complete

list of

perf_test utility options, is perf_test on page 163.

For best results, take the following factors into consideration when running the

perf_test utility.

Memory Access Patterns

The perf_test memory access modes include random, sequential, and single-

address. Accessing just a single address can radically impact the performance

a device can deliver, as can sequential and random access. So, know which

address access mode is being used when running tests.

Threading and Asynchronous I/O

Use perf_test to specify the number of threads to spawn and the number of

outstanding I/Os within each request.

The Linux operating system tends to deal with larger asynchronous I/O depths

better than a larger number of threads. High amounts of I/O can be achieved by

understanding the operating system behavior and using a combination of thread

counts and asynchronous I/O.

2 817.132 MB/s0.000 MB/s817.132 MB/s1994950199495

3 817.160 MB/s0.000 MB/s817.160 MB/s1995010199501

4 817.096 MB/s0.000 MB/s817.096 MB/s1994860199486

-s memory-size

Specifies the system memory size, in GB (if no

units are provided). Recognized unit/size

qualifiers include:

k, K, m, M, g and G for the

appropriate binary multipliers.

-t num-threads

Specifies the number of threads to invoke. Each

thread is governed by the options specified for

reads, writes, verification, block size, and so on,

and operates independently in terms of

randomness of addresses touched.

-R

Selects addresses to read/write randomly.

-o

Informs perf_test to bypass the buffer cache by

using the

O_DIRECT flag when opening a

connection to the device-path. This option applies

to block devices only and not character devices.

-A async-io-depth

Specifies the number of I/Os to generate using

the operating system’s asynchronous I/O API.

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