trace: cpu_freq_switch: Add profiler for CPU frequency switch times
It is sometimes useful to profile how long CPU frequency switches
take, and traces have already been added for this purpose. Make
use of these and the trace_stat framework to generate statistical
histograms of frequency switch times in the following format:
# cat /sys/kernel/debug/tracing/trace_stat/cpu_freq_switch
CPU START_KHZ END_KHZ COUNT AVG_US MIN_US MAX_US
| | | | | | |
0 384000 1512000 3 2787 1648 3418
0 486000 384000 1 1129 1129 1129
0 1458000 384000 1 3174 3174 3174
0 1512000 384000 1 3265 3265 3265
0 1512000 486000 1 3235 3235 3235
0 1512000 1458000 1 213 213 213
0 1512000 1512000 1 0 0 0
Profiling is disabled by default (since it does incur some
overhead). It can be enabled or re-disabled echoing 1 or 0
to /sys/kernel/debug/tracing/cpu_freq_switch_profile_enabled
Change-Id: I3ef7f9d681b7bd13bcaa031003b10312afe1aefe
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>
3 files changed