MySQL 8.0 Release Notes
MySQL 8.0 Source Code Documentation
These views summarize file I/O, grouped by host. By default, rows are sorted by descending total file I/O latency.
The host_summary_by_file_io and
x$host_summary_by_file_io views
have these columns:
hostThe host from which the client connected. Rows for which the
HOSTcolumn in the underlying Performance Schema table isNULLare assumed to be for background threads and are reported with a host name ofbackground.iosThe total number of file I/O events for the host.
io_latencyThe total wait time of timed file I/O events for the host.