Examples for gathering and reading DASD statistics in debugfs

6.18 LPAR mode z/VM guest KVM guest

Use the echo command to start and stop data gathering for individual devices or across all DASDs. Use the cat command to access the raw performance data.

The following examples assume that debugfs is mounted at /sys/kernel/debug.

To start data gathering for summary data across all available DASDs:
```
# echo on > /sys/kernel/debug/dasd/global/statistics
```

To stop data gathering for block device dasdb:

# echo off > /sys/kernel/debug/dasd/dasdb/statistics

To reset the counters for CCW device 0.0.b301:

# echo reset > /sys/kernel/debug/dasd/0.0.b301/statistics

To read performance data for dasda, assuming that the degbugfs mount point is /sys/kernel/debug, issue:

# cat  /sys/kernel/debug/dasd/dasda/statistics
start_time 1283518578.085869197
total_requests 0
total_sectors 0
total_pav 0
total_hpf 0
histogram_sectors 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
histogram_io_times 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
histogram_io_times_weighted 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
histogram_time_build_to_ssch 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
histogram_time_ssch_to_irq 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
histogram_time_ssch_to_irq_weighted 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
histogram_time_irq_to_end 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
histogram_ccw_queue_length 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
total_read_requests 0
total_read_sectors 0
total_read_pav 0
total_read_hpf 0
histogram_read_sectors 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
histogram_read_times 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
histogram_read_time_build_to_ssch 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
histogram_read_time_ssch_to_irq 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
histogram_read_time_irq_to_end 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
histogram_read_ccw_queue_length 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0