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System Administration Guide

How to Check System Call Statistics (sar)

Display system call statistics by using the sar -c command. 


$ sar -c
SunOS venus 5.6 Generic sun4m    08/20/96
00:00:03 scall/s sread/s swrit/s fork/s exec/s rchar/s wchar/s
01:00:02       9       0       0   0.01   0.01      33       9

Table 64-9 describes the following system call categories reported by the -c option. Typically, reads and writes account for about half of the total system calls, although the percentage varies greatly with the activities that are being performed by the system.

Table 64-9 Output from the sar -c Command

Field Name 

Description 

scall/s

All types of system calls per second (generally about 30 per second on a busy four- to six-user system) 

sread/s

read system calls per second

swrit/s

write system calls per second

fork/s

fork system calls per second (about 0.5 per second on a four- to six-user system); this number will increase if shell scripts are running

exec/d

exec system calls per second; if exec/s divided by fork/s is greater than three, look for inefficient PATH variables

rchar/s

Characters (bytes) transferred by read system calls per second

wchar/s

Characters (bytes) transferred by write system calls per second

Example--Checking System Call Statistics

The following example shows output from the sar -c command.


$ sar -c
Solaris mysys Solaris sun4c    08/22/96
14:28:12 scall/s sread/s swrit/s  fork/s  exec/s rchar/s wchar/s
14:29:12      17       2       2    0.28    0.28    2527    1542
14:30:12      25       2       1    0.50    0.47    1624     295
14:31:12      21       2       2    0.35    0.35    1812     703
 
Average       21       2       2    0.38    0.37    1987     847