nxstat Command

Purpose

The nxstat command displays usage statistics of on-chip hardware accelerators that can implement GZIP functions.

Syntax

nxstat {-S | [-AUWT] [-a accel_type] [-u unit_index ] [-w window_index] [-t window_type] interval [count]}

Description

Applications in an AIX logical partition use the zlibNX library to open a communication channel with the GZIP accelerator. This communication channel is also known as a window. For more information about the type of communication channels, see Nest Accelerators.

The low-level usage statistics per window might include a large amount of data that might not be relevant for a system administrator. The nxstat command can aggregate the usage statistics to provide global usage statistics for a specific accelerator type or for a specific hardware accelerator unit based on the options and arguments that are specified with the command.

The following values are displayed in the usage statistics for each aggregation level along with the window type and corresponding credits:

Opens: Number of open and close operations on a window.
Bytes: Number of bytes processed by the hardware accelerator unit.
Faults: Number of page faults that are detected by the hardware accelerator unit.
Intrs: Number of completion interrupts. This value is optional for accelerator operations.
Polls: Number of completion interrupts that are detected during the polling phase of the nxstat command.
Waits: Number of operations that were completed after the caller was actually blocked. The total of Polls and Waits values represent the total number of operations that were completed during the specific time interval.

The kernel service that waits for completion of active GZIP operations, first polls a completion bit for a period of time before blocking the thread. Total count of Polls and Waits values provide insight about efficiency and usefulness of the polling phase.

The nxstat command aggregates the usage statistics of a specific accelerator type during a specified time interval. The nxstat command can also display the accelerator usage statistics for successive time intervals. The -A, -U, -T, and -W flags determine the aggregation levels. If more than one flags are specified, for example, -AU, the nxstat command displays usage statistics for both aggregation levels. The -a, -u, -t, -w flags are used to limit the statistics data to specific objects such as accelerator unit, window, and window type.

Flags

-S

Displays types of accelerators that are available.

-A

Displays usage statistics for a specific type of accelerator. This is the default option.

-U

Displays usage statistics for a specific hardware accelerator unit.

-T

Displays usage statistics for a specific window type.

-W

Displays usage statistics for each window.

-a

Specifies the accelerator type for which the usage statistics is displayed. The -a flag value for the GZIP accelerator is 0. Currently, the only supported value for the -a flag is 0. Therefore, if you do not specify the -a flag, the default value of 0 is applied.

-u

Specifies the accelerator unit for which the usage statistics is displayed. You must specify the -u flag only with the -U flag. The accelerator unit index value for this flag is a number between zero and the number of accelerator units minus 1. For example, if the AIX logical partition has access to three accelerator units, valid values that can be specified for this flag are 0, 1, and 2.

If the -u flag is not specified along with the -U flag, the nxstat command displays the data for all the hardware accelerator units that can be accessed by the logical partition.

-w

Specifies a specific window for which the usage statistics is displayed. If the logical partition has access to n windows, the windows are numbered from 0 to n-1. You can specify the -w flag only with the -W flag.

-t

Specifies a specific window type (0 for Quality of Service (QoS), 1 for default) for which the usage statistics is displayed. You can specify the -t flag only with the -T flag.

Note: The -u, -w and -t flags are mutually exclusive.

interval

Specifies the time interval, in seconds, during which the usage statistics must be captured. This flag is mandatory. By default, the kernel service captures usage statistics every 2 seconds, so you must specify a time interval more than 2 seconds to display useful data.

count

Specifies the number of successive time intervals for which you want to display the usage statistics. The default value is 1.

Examples

To display total usage statistics for all the accelerator type and for all window types, run the following command:

nxstat 10 4

An output that is similar to the following example is displayed:

Accelerator GZIP:   Window Types:  2    Units:  1   Credits:   72
Type Cred   Opens          Bytes   Faults      Intrs         Polls         Waits
 ALL   72  266826      35.747 GB        0      17281        222795         61223
 ALL   72  262812      35.638 GB        0      17524        220368         59641
 ALL   72  300647      33.583 GB        0      15990        257351         58969
 ALL   72  259405      35.557 GB        0      17111        216629         60048

 ** Average **
 ALL   72  272422      35.131 GB        0      16976        229285         59970

To display accelerator level statistics by window type, run the following command:

nxstat -AT 10

An output that is similar to the following example is displayed:

Accelerator GZIP:   Window Types:  2    Units:  4   Credits:   92
Type Cred   Opens          Bytes   Faults      Intrs         Polls         Waits
 QOS   12         0    49.892 GB        0      28695          4998         52476
 DEF   80         0     4.406 GB        0       2561           422          4654

To display unit level statistics by accelerator unit, run the following command:

nxstat -U 10 4

An output that is similar to the following example is displayed:

  Unit Index  0:   SRAD ID         0  Window Types:  2    Credits:   23
Type Cred   Opens          Bytes   Faults      Intrs         Polls         Waits
 ALL   23       0      16.735 GB        0       9589          1551         17728

  Unit Index  1:   SRAD ID         1  Window Types:  2    Credits:   23
Type Cred   Opens          Bytes   Faults      Intrs         Polls         Waits
 ALL   23       0      12.438 GB        0       7219          1270         13058

  Unit Index  2:   SRAD ID         2  Window Types:  2    Credits:   23
Type Cred   Opens          Bytes   Faults      Intrs         Polls         Waits
 ALL   23       0      12.427 GB        0       7131          1310         13006

  Unit Index  3:   SRAD ID         3  Window Types:  2    Credits:   23
Type Cred   Opens          Bytes   Faults      Intrs         Polls         Waits
 ALL   23       0      12.430 GB        0       7230          1383         12935

To display types of accelerators that are available, run the following command:
```
nxstat -S
```
An output that is similar to the following example is displayed:
```
GZIP accelerator available
```