Red Hat ENTERPRISE LINUX 4 - INTRODUCTION TO SYSTEM ADMINISTRATION Administration Manual

Also see for ENTERPRISE LINUX 4 - DEVELOPER TOOLS GUIDE: Installation guide Installation guide Tuning guide Installation guide Manual

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56 Chapter 4. Physical and Virtual Memory(modified) and may need to be written to disk. The inaclnpg field, on the other hand, shows howmany inactive pages are clean (unmodified) and do not need to be written to disk.The inatarpg field represents the desired size of the inactive list. This value is calculated by theLinux kernel and is sized such that the inactive list remains large enough to act as a pool for pagereplacement purposes.For additional insight into page status (specifically, how often pages change status), use the sar -Rreport. Here is a sample report:Linux 2.4.20-1.1931.2.231.2.10.entsmp (raptor.example.com) 07/22/200312:00:01 AM frmpg/s shmpg/s bufpg/s campg/s12:10:00 AM -0.10 0.00 0.12 -0.0712:20:00 AM 0.02 0.00 0.19 -0.07...08:50:01 PM -3.19 0.00 0.46 0.81Average: 0.01 0.00 -0.00 -0.00The statistics in this particular sar report are unique, in that they may be positive, negative, or zero.When positive, the value indicates the rate at which pages of this type are increasing. When negative,the value indicates the rate at which pages of this type are decreasing. A value of zero indicates thatpages of this type are neither increasing or decreasing.In this example, the last sample shows slightly over three pages per second being allocated from thelist of free pages (the frmpg/s field) and nearly 1 page per second added to the page cache (thecampg/s field). The list of pages used as buffers (the bufpg/s field) gained approximately one pageevery two seconds, while the shared memory page list (the shmpg/s field) neither gained nor lost anypages.4.7. Additional ResourcesThis section includes various resources that can be used to learn more about resource monitoring andthe Red Hat Enterprise Linux-specific subject matter discussed in this chapter.4.7.1. Installed DocumentationThe following resources are installed in the course of a typical Red Hat Enterprise Linux installationand can help you learn more about the subject matter discussed in this chapter.• free(1) man page — Learn how to display free and used memory statistics.• vmstat(8) man page — Learn how to display a concise overview of process, memory, swap, I/O,system, and CPU utilization.• sar(1) man page — Learn how to produce system resource utilization reports.• sa2(8) man page — Learn how to produce daily system resource utilization report files.4.7.2. Useful Websites• http://people.redhat.com/alikins/system_tuning.html — System Tuning Info for Linux Servers. Astream-of-consciousness approach to performance tuning and resource monitoring for servers.• http://www.linuxjournal.com/article.php?sid=2396 — Performance Monitoring Tools for Linux.This Linux Journal page is geared more toward the administrator interested in writing a customized