4.11.3 Detecting Bottlenecks on UNIX

On UNIX systems, the sar(1) command provides valuable performance information that can be used to find system bottlenecks. You can use the sar(1) command to:

• Sample cumulative activity counters in the operating system at predetermined intervals.
• Extract data from a system file.

The following table describes the sar(1) command options.

Table 4-6 sar(1) Command Options (Continued)

Option	Description
-u	Gathers CPU utilization numbers, including the portion of the time running in user mode, running in system mode, idle with some process waiting for block I/O, and otherwise idle.
-b	Reports buffer activity, including transfers per second of data between system buffers and disk, or other block devices.
-c	Reports system call activity. This includes system calls of all types, as well as specific system calls such as fork(2) and exec(2).
-w	Monitors system swapping activity. This includes the number of transfers for swap-ins and swap-outs.
-q	Reports average queue lengths while occupied and the percent of time occupied.
-m	Reports message and system semaphore activities, including the number of primitives per second.
-p	Reports paging activity, including the address translation page faults, page faults and protection errors, and the valid pages reclaimed for free lists.
-r	Reports unused memory pages and disk blocks, including the average number of pages available to user processes and the disk blocks available for process swapping.

Note:

Some UNIX platforms do not provide the sar(1) command, but offer equivalent commands instead. BSD, for example, offers the iostat(1) command. Sun Microsystems, Inc. offers perfmeter(1).