Tunable Kernel Parameters

Tunables (or configurable kernel parameters) are kernel variables that allow the operating system to be configured to fit specific system needs, resulting in better performance and/or more efficient allocation of resources. The ideal value for each parameter is often determined by the system’s particular hardware configuration, the specific mix of applications the system runs, and the trustworthiness of system users: factors that vary widely from system to system.HP attempts to provide reasonable default parameter settings, but it may be necessary or beneficial to modify these settings to better suit the needs of your particular system’s users. Refer to the individual manpage to obtain detailed information about any configurable kernel parameter.

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Table of contents :
Tunable Kernel Parameters……Page 1
Legal Notices……Page 2
Revision History……Page 3
Conventions……Page 4
1 Overview……Page 9
Tunables by Subsystem……Page 10
Tunable Kernel Parameters……Page 11
Manpage Layout……Page 12
Formula Values……Page 13
Undocumented Kernel Parameters……Page 14
2 Accounting Subsystem……Page 15
Additional Information……Page 16
Resume Accounting Threshold……Page 17
Examples……Page 18
Additional Information……Page 19
3 Asynchronous I/O Subsystem……Page 21
Asynchronous I/O Parameter Summary……Page 22
4 File System Subsystem……Page 23
Journaled File Systems (VxFS) Parameter Summary……Page 24
Disk Read-Ahead Parameter Summary……Page 25
Asynchronous Writes Parameter Summary……Page 26
Recommended Procedure……Page 27
Additional Information……Page 28
Additional Information……Page 29
Additional Information……Page 30
5 Interprocess Communication (IPC) Subsystem……Page 31
Semaphore Parameter Summary……Page 32
Shared Memory Parameter Summary……Page 33
System V Interprocess Communication Mechanisms……Page 34
Message and Message Queue Management……Page 35
System Globals……Page 36
Semaphore Limits……Page 37
Shared Memory Access and Use……Page 38
6 Kernel Crash Dump Subsystem……Page 39
Kernel Crash Dump Parameter Summary……Page 40
7 Memory Paging Subsystem……Page 41
Variable Page Size Parameter Summary……Page 42
Additional Information……Page 43
Device Swap……Page 44
Additional Information……Page 45
8 Process Management Subsystem……Page 47
Memory Space Parameter Summary……Page 48
Kernel Threads Parameter Summary……Page 49
CPU Timesharing Management……Page 50
Selecting Limits……Page 51
9 Spinlock Pool……Page 53
Spinlock Pool Parameter Summary……Page 54
Description……Page 55
10 Streams Subsystem……Page 57
Streams Parameter Summary……Page 58
Overview of Streams Kernel Parameters……Page 59
11 Miscellaneous Parameters……Page 61
Intrusion Detection System/9000……Page 62
Real-Time Priority Parameter Summary……Page 63
Web Server Parameter Summary……Page 64
A Table of Tunable Kernel Parameters……Page 65