System information

100 System Analysis and Tuning Guide
The data is located under /sys/kernel/debug/perfmon/ and organized
per CPU. Each CPU contains a set of metrics, accessible as ASCII file. The fol-
lowing data is taken from the /usr/src/linux/Documentation/perf
mon2-debugfs.txt:
Table7.3: Read-Only Files in /sys/kernel/debug/perfmon/cpu*/
File Description
ctxswin_count Number of PMU context switch in
ctxswin_ns Number of nanoseconds spent in the
PMU context switch in routine
Average cost of the PMU context
switch in =
ctxswin_ns / ctxswin_count
ctxswout_count Number of PMU context switch out
ctxswout_ns Number of nanoseconds spend in the
PMU context switch out routine
Average cost of the PMU context
switch out =
ctxswout_ns / ctxswout_count
fmt_handler_calls Number of calls to the sampling for-
mat routine that handles PMU inter-
rupts (typically the routine that recors
a sample)
fmt_handler_ns Number of nanoseconds spent in the
routine that handle PMU interrupt in
the sampling format
Average time spent in this
routine =
fmt_handler_ns /
fmt_handler_calls
handle_timeout_count Number of times the
pfm_handle_timeout() routine