IBM REDP-4285-00 E, F, G, H, I, J, K, L, M

4285IX.fm Draft Document for Review May 4, 2007 11:35 am

150 Linux Performance and Tuning Guidelines

E

elevator

See I/O elevator

Enterprise Linux distributions 93

ethereal command 55, 57

ethtool command 126–127

exec() 4

exit() 4

Ext2 17–18, 121

Ext3 18–19, 121, 123

extended 2 file system

See Ext2

extended 3 file system

See Ext3

eXtended File System 19, 121

F

faulty adapters 88

Fibre Channel controllers 85

file system 15–19

Ext2 17–18

Ext3 18–19

eXtended File System 19

Journal File System 19

journaling 16

ReiserFS 19

selection 121–125

tuning 121–125

virtual file system 15

file system selection 93

FIN packet 30

fork() 4

free command 46

memory used in a zone 47

G

getty 15

Gnome System Monitor 67

gpm 97

H

hardware considerations 114

hpoj 98

HugeTLBfs 112

I

I/O elevator 20, 23–24, 113, 116–120

anticipatory 24, 117–118

Complete Fair Queuing 24, 116–118, 122

deadline 24, 116–117

NOOP 24, 117–118

selection 116–120

tuning 116–120

I/O subsystem architecture 20

IBM Director 67

init command 101

installation considerations 92–104

interrupt handling 6

bind an interrupt to a CPU 7, 109

CPU affinity 109

interrupts

decreasing 136

ionice 122

iostat command 48, 86

IOzone 72

iptraf 54

irq subdirectory 62

irqbalance 98

isdn 98

J

JFS

See Journal File System

Journal File System 19, 121, 123

journaling 16, 113

mode 123

K

KDE System Guard 62–67, 82

Process Table 65

System Load 64

kernel

changing parameters 104–108

compiling 104

swap behavior 110

view current configuration 105

kernel panic 87

kudzu 98

L

LD_ASSUME_KERNEL 5

libpcap library 55

Light Weight Process 4

Linux

distributions 93

installation considerations 92–104

performance metrics 34–36

Linux Security Modules 104

LinuxThreads 5

LMbench 71

locality of reference 21

LSM

See Linux Security Modules

LWP

See Light Weight Process

M

maximum transmission unit 33, 127–129

size 127

memory

32-bit architectures 11

64-bit architectures 11

memory architecture 11–15

memory bottlenecks 82–84

actions 84

Contents

Main Page Page Page Contents Page Page Page Notices Trademarks Preface How this Redpaper is structured The team that wrote this Redpaper Become a published author Comments welcome Page operating system Page 1.1 Linux process management 1.1.1 What is a process? 1.1.2 Lifecycle of a process 1.1.3 Thread 1.1.4 Process priority and nice level Process priority 1.1.5 Context switching CPU 1.1.6 Interrupt handling Suspend Resume 1.1.7 Process state Processor Zombie processes 1.1.8 Process memory segments Text Data Stack Process address space 1.1.9 Linux CPU scheduler 4285ch01.fm 10 Figure 1-8 Linux kernel 2.6 O(1) scheduler via scheduler_tick() P active expired array[0] array[1] PP P active expired array[0] array[1] PP Parent Child 1.2 Linux memory architecture 1.2.1 Physical and virtual memory Virtual memory addressing layout 32-bit Architecture 64-bit Architecture User space Kernel space 32-bit Architecture 64-bit Architecture User space Kernel space 1.2.2 Virtual memory manager Page frame allocation Buddy system Page frame reclaiming cache and process address space. The page cache is pages mapped to a file on disk. The swap 1.3 Linux file systems 1.3.1 Virtual file system 1.3.2 Journaling 1. write journal logs write File system Journal area 1.3.3 Ext2 Ext2 1.3.4 Ext3 Mode of journaling 1.3.5 ReiserFS 1.3.6 Journal File System 1.3.7 XFS 1.4 Disk I/O subsystem 1.4.1 I/O subsystem architecture 1.4.2 Cache Memory hierarchy Locality of reference Flushing dirty buffer 1.4.3 Block layer Disk Cache Disk Cache Block sizes 1.4.4 I/O device driver SCSI ips qla2300mptscsih 1.4.5 RAID and Storage system st sr_modsd_modsg scsi_mod Upper level driver Mid level driver Device Process Low level driver 1.5 Network subsystem 1.5.1 Networking implementation Socket buffer TCP/IP IPX Appletalk DEVICE NAPI way NAPI way DEVICE Netfilter Netfilter Connection tracking 1.5.2 TCP/IP Connection establishment Chapter 1. Understanding the Linux operating system 31 Draft Document for Review May 4, 2007 11:35 am 4285ch01.fm Figure 1-27 TCP 3-way handshake Client Server 4285ch01.fm 32 Traffic control TCP/IP transfer window CLOSED LISTEN SYN SENT LAST-ACK ESTAB SYN RCVD 1.5.3 Offload 1.5.4 Bonding module 1.6 Understanding Linux performance metrics 1.6.1 Processor metrics 1.6.2 Memory metrics 1.6.3 Network interface metrics 1.6.4 Block device metrics transfers per second metric in conjunction with the kBytes per second value helps you to Page Page Page 2.1 Introduction 2.2 Overview of tool function 2.3 Monitoring tools 2.3.1 top 2.3.2 vmstat 2.3.3 uptime 2.3.4 ps and pstree Page Thread information 2.3.5 free Memory used in a zone 2.3.6 iostat Page 2.3.7 sar 2.3.8 mpstat 2.3.9 numastat 2.3.10 pmap 2.3.11 netstat 2.3.12 iptraf 2.3.13 tcpdump / ethereal tcpdump ethereal 2.3.14 nmon 2.3.15 strace 2.3.16 Proc file system Page 2.3.17 KDE System Guard Work space System Load Process Table Configuring a work sheet Page 2.3.18 Gnome System Monitor 2.3.19 Capacity Manager Page Page 2.4 Benchmark tools 2.4.1 LMbench 2.4.2 IOzone 2.4.3 netperf Page Page 2.4.4 Other useful tools bottlenecks 3.1 Identifying bottlenecks 3.1.1 Gathering information Page 3.1.2 Analyzing the servers performance 3.2 CPU bottlenecks 3.2.1 Finding CPU bottlenecks 3.2.2 SMP 3.2.3 Performance tuning options 3.3 Memory bottlenecks 3.3.1 Finding memory bottlenecks Paging and swapping indicators 3.3.2 Performance tuning options 3.4 Disk bottlenecks 3.4.1 Finding disk bottlenecks vmstat command iostat command 3.4.2 Performance tuning options 3.5 Network bottlenecks 3.5.1 Finding network bottlenecks Page 3.5.2 Performance tuning options Page Page 4.1 Tuning principals 4.1.1 Change management 4.2 Installation considerations 4.2.1 Installation Page 4.2.2 Check the current configuration dmesg Page ulimit 4.2.3 Minimize resource use Daemons Page Page Page Changing runlevels Limiting local terminals 4.2.4 SELinux SELinux Kernel Process User Request Access Grant Access Grant/Deny Access Based on Policy 4.3 Changing kernel parameters Page Page 4.3.1 Where the parameters are stored 4.3.2 Using the sysctl command 4.4 Tuning the processor subsystem 4.4.1 Tuning process priority 4.4.2 CPU affinity for interrupt handling 4.4.3 Considerations for NUMA systems numactl 4.5 Tuning the vm subsystem 4.5.1 Setting kernel swap and pdflush behavior 4.5.2 Swap partition 4.5.3 HugeTLBfs 4.6 Tuning the disk subsystem 4.6.1 Hardware considerations before installing Linux Number of drives Guidelines for setting up partitions 4.6.2 I/O elevator tuning and selection Selecting the right I/O elevator in kernel 2.6 Page Impact of nr_requests Page Impact of read_ahead_kb 4.6.3 File system selection and tuning Using ionice to assign I/O priority Access time updates Select the journaling mode of the file system Block sizes stripe size of the array (or segment in the case of Fibre Channel). The stripe-unit size is the 4.7 Tuning the network subsystem 4.7.1 Considerations of traffic characteristics 4.7.2 Speed and duplexing 4.7.3 MTU size 4.7.4 Increasing network buffers Tuning window sizes Page Impact of socket buffer size 4.7.5 Additional TCP/IP tuning Tuning IP and ICMP behavior Page Tuning TCP behavior Tuning TCP options Chapter 4. Tuning the operating system 133 Draft Document for Review May 4, 2007 11:35 am 4285ch04.fm Figure 4-19 Netfilter rules applied 4.7.6 Performance impact of Netfilter Figure 4-18 No Netfilter rule applied TCP_CRR benchmark TCP_CRR benckmark TCP_CRR benchmark 4.7.7 Offload configuration Impact of offloading Chapter 4. Tuning the operating system 135 Draft Document for Review May 4, 2007 11:35 am 4285ch04.fm Figure 4-21 Throughput degradation by offloading Figure 4-20 CPU usage improvement by offloading cpu usage improvement - default vs offload off 4.7.8 Increasing the packet queues 4.7.9 Increasing the transmit queue length 4.7.10 Decreasing interrupts Page Page Page 4285ax01.fm 140 Hardware and software configurations Linux installed on guest IBM z/VM systems Linux installed on IBM System x servers Three IBM System x x236 servers were configured as shown in TableA-2. Page Page Abbreviations and acronyms 4285abrv.fm 144 Related publications IBM Redbooks Other publications Online resources Page How to get IBM Redbooks Help from IBM Page Index Symbols Numerics A B E F G H I N O P 4285IX.fm 152 Q R S T U V W X Z Page Page Redpaper Back cover INTERNATIONAL TECHNICAL SUPPORT ORGANIZATION Linux Performance and Tuning Guidelines