Obtaining QDIO performance statistics

7.1 LPAR mode z/VM guest

There is a debugfs interface for QDIO performance statistics. These statistics apply to FCP devices and to qeth devices.

This topic is meant primarily for service.

QDIO performance statistics are available by device. These statistics are located in

<debugfs_mount>/qdio/<device_bus_id>/statistics

where <debugfs_mount> is the mount point for debugfs and <device_bus_id> is the bus ID of an FCP or qeth device.

Write 1 to the statistics file of a device to start collecting performance data for that device. Write 0 to this file to stop collecting performance data. By default no data is collected. Data is written to a statistics file and one ore more files named input_* and output_*.

You can use the cat command to read the data from the input_*, output_*, and statistics files.

Example

Assuming that debugfs is mounted at /sys/kernel/debug, the following command starts performance data collection for a device with bus ID 0.0.fc00:

# echo 1 > /sys/kernel/debug/qdio/0.0.fc00/statistics

The following command reads the collected data:

# cat /sys/kernel/debug/qdio/0.0.fc00/statistics