26.4.3.3 The host_summary_by_file_io_type and x$host_summary_by_file_io_type Views

These views summarize file I/O, grouped by host and event type. By default, rows are sorted by host and descending total I/O latency.

host

The host from which the client connected. Rows for which the HOST column in the underlying Performance Schema table is NULL are assumed to be for background threads and are reported with a host name of background.
event_name

The file I/O event name.
total

The total number of occurrences of the file I/O event for the host.
total_latency

The total wait time of timed occurrences of the file I/O event for the host.
max_latency

The maximum single wait time of timed occurrences of the file I/O event for the host.