System Administration Guide

How to Check Page-In Activity (sar)

Use the sar -p command to report page-in activity which includes protection and translation faults.


$ sar -p
SunOS venus 5.6 Generic sun4m    08/20/96
00:00:03 atch/s pgin/s ppgin/s pflt/s vflt/s slock/s
01:00:02   0.00   0.00    0.00   0.49   1.20    0.00

The reported statistics from the -p option are described in Table 64-14.

Table 64-14 Output from the sar -p Command

Field Name 

Description 

atch/s

The number of page faults, per second, that are satisfied by reclaiming a page currently in memory (attaches per second). Instances of this include reclaiming an invalid page from the free list and sharing a page of text currently being used by another process (for example, two or more processes accessing the same program text). 

pgin/s

The number of times, per second, that file systems receive page-in requests. 

ppgin/s

The number of pages paged in, per second. A single page-in request, such as a soft-lock request (see slock/s), or a large block size, may involve paging-in multiple pages.

pflt/s

The number of page faults from protection errors. Instances of protection faults are illegal access to a page and "copy-on-writes." Generally, this number consists primarily of "copy-on-writes." 

vflt/s

The number of address translation page faults, per second. These are known as validity faults, and occur when a valid process table entry does not exist for a given virtual address. 

slock/s

The number of faults, per second, caused by software lock requests requiring physical I/O. An example of the occurrence of a soft-lock request is the transfer of data from a disk to memory. The system locks the page that is to receive the data, so that it cannot be claimed and used by another process.  

Example--Checking Page-In Activity

The following example shows output from sar -p.


$ sar -p
SunOS venus 5.6 Generic sun4m    08/20/96
 
14:28:12  atch/s  pgin/s ppgin/s  pflt/s  vflt/s slock/s
14:29:12    1.17   12.87   12.87    5.67   11.28    1.15
14:30:12    1.67    7.08    7.08    9.12    6.33    0.67
14:31:12    1.37   12.48   12.48    6.83   10.78    1.03
 
Average     1.40   10.81   10.81    7.21    9.46    0.95