Commands Reference, Volume 1

alstat Command

Purpose

Shows alignment exception statistics.

Syntax

alstat [ -e | -v ] [ Interval ] [ Count ]

Description

The alstat command displays alignment exception statistics. Alignment exceptions may occur when the processor cannot perform a memory access due to an unsupported memory alignment offset (such as a floating point double load from an address that is not a multiple of 8). However, some types of unaligned memory references may be corrected by some processors and does not generate an alignment exception.

The alignment exception count since the last time the machine was rebooted and the count in the current interval are displayed. You can optionally display emulation exception statistics or individual processor alignment statistics.

The default output displays statistics every second. The sampling Interval and Count of iterations can be also specified.

Implementation Specifics

This command is valid only on the POWER-based platform.

Parameters

Flags

Examples

1. To display alignment exception statistics every second, type:

   alstat
   

   This produces the following output:

     Alignment  Alignment
     SinceBoot      Delta
       8845591          0
       8845591          0
       8845591          0
       8845591          0
       8845591          0
       8845591          0
     ...
     
   

2. To display emulation and alignment exception statistics every two seconds, a total of 5 times, type:

   alstat -e 2 5
   

   This produces the following output:

     Emulation  Emulation  Alignment  Alignment
     SinceBoot      Delta  SinceBoot      Delta
      21260604          0   70091846          0
      23423104    2162500   72193861    2102015
      25609796    2186692   74292759    2098898
      27772897    2163101   76392234    2099475
      29958509    2185612   78490284    2098050
   

3. To display alignment exception statistics, every 5 seconds, for each processor, type:

   alstat -v 5
   

   This produces the following output:

     Alignment  Alignment  Alignment  Alignment
     SinceBoot      Delta    Delta00    Delta01
      88406295          0          0          0
      93697825    5291530          0    5291530
      98930330    5232505    5232505          0
     102595591    3665261     232697    3432564
     102595591          0          0          0
   

Related Information

The emstat command.