Red Hat NETWORK WORKGROUP - USER 1.0 Przewodnik Instalacji Pobierz pdf (Strona 40)

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3: SGI Peformance Suite Products Overview

Operating System Enhancements

BuildingontheLinuxoperatingsystem’srapidexpansionandimprovementsforgeneral

commercial and enterprise environments, SGI has focused on improving Linux

capabilitiesandperformance speciﬁcallyfor high performancecomputing’s(HPC’s) big

compute and big data environments. Thus, SGI has leveraged its experience with

NUMAﬂexandHPCfromitsIRIXoperatingsystemsandMIPSprocessor-basedsystems

and concentrated on the Linux kernel improvements speciﬁcally important to HPC

environments.

Cpuset Support

The cpuset facility is primarily a workload manager tool permitting a system

administrator to restrict the number of processors and memory resources that a process

orsetofprocessesmayuse.AcpusetdeﬁnesalistofCPUsandmemorynodes.Aprocess

containedin acpuset mayonly executeon theCPUs inthatcpusetandmayonlyallocate

memory on the memory nodes in that cpuset. Essentially, cpusets provide you with a

CPUand memorycontainers or"softpartitions"withinwhich youcan runsetsofrelated

tasks. Usingcpusets on an SGIAltix system improves cachelocality and memory access

times and can substantially improve an applications performance and runtime

repeatability. Restrainingallother jobs fromusing anyofthe CPUs ormemoryresources

assigned to a critical job minimizes interference from other jobs on the system. For

example,MessagePassing Interface(MPI)jobs frequentlyconsist ofanumber of threads

that communicate using message passing interfaces. All threads need to be executing at

the same time. If a single thread loses a CPU, all threads stop making forward progress

and spin at a barrier. Cpusets can eliminate the need for a gang scheduler.

Cpusets are represented in a hierarchical virtual ﬁle system. Cpusets can be nested and

they have ﬁle-like permissions.

In addition to their traditional use to control the placement of jobs on the CPUs and

memory nodes of a system, cpusets also provide a convenient mechanism to control the

use of Hyper-Threading Technology.

For detailed information on cpusets, see Chapter 6, “Cpusets on SGI ProPack 6 for

Linux” in the Linux Resource Administration Guide.

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Red Hat NETWORK WORKGROUP - USER 1.0 Przewodnik Instalacji Strona 40