In POWER8, OCC(On-Chip-Controller) can throttle the frequency of the CPU when the chip crosses its thermal and power limits. Currently, powernv-cpufreq driver detects and reports this event as a console message. Some machines may not sustain the max turbo frequency in all conditions and can be throttled frequently. This can lead to the flooding of console with throttle messages. So this patchset aims to redesign the presentation of this event via sysfs counters and tracepoints. And it also fixes couple of bugs reported in the driver.
- Patch [1] fixes a memory leak bug - Patch [2] fixes the cpu hot-plug bug in powernv_cpufreq_work_fn(). - Patch [3] solves a bug in powernv_cpufreq_throttle_check(), which calls in to cpu_to_chip_id() in hot path which reads DT every time to find the chip id. - Patches [4] to [6] will add a perf trace point "power:powernv_throttle" and sysfs throttle counter stats in /sys/devices/system/cpu/cpufreq/chipN. Changes from v7: - Changes in patch[6] involves adding a table to represent the throtle stats in frequency X reason layout. Detailed version log in the patch. Changes from v6: - Changes wrt comments from Balbir Singh and Viresh Kumar. Details in the version log of the patches. Changes from v5: - Fix kbuild error: drivers/cpufreq/powernv-cpufreq.c:428:2: error: implicit declaration of function 'get_online_cpus' [-Werror=implicit-function-declaration] Changes from v4: - Fix a hot-plug bug in powernv_cpufreq_work_fn() - Changes wrt Gautham's and Shreyas's comments Changes from v3: - Add a fix to replace cpu_to_chip_id() with simpler PIR shift to obtain the chip id. - Break patch2 in to two patches separating the tracepoint and sysfs attribute changes. Changes from v2: - Fixed kbuild test warning. drivers/cpufreq/powernv-cpufreq.c:609:2: warning: ignoring return value of 'kstrtoint', declared with attribute warn_unused_result [-Wunused-result] Shilpasri G Bhat (6): cpufre: powernv: Free 'chips' on module exit cpufreq: powernv: Hot-plug safe the kworker thread cpufreq: powernv: Remove cpu_to_chip_id() from hot-path cpufreq: powernv/tracing: Add powernv_throttle tracepoint cpufreq: powernv: Replace pr_info with trace print for throttle event cpufreq: powernv: Add sysfs attributes to show throttle stats Documentation/ABI/testing/sysfs-devices-system-cpu | 66 +++++ drivers/cpufreq/powernv-cpufreq.c | 303 +++++++++++++++++---- include/trace/events/power.h | 22 ++ kernel/trace/power-traces.c | 1 + 4 files changed, 337 insertions(+), 55 deletions(-) -- 1.9.3
