[PATCH RESEND v4 0/4] cpufreq: powernv: Redesign the presentation of throttle notification
From: Shilpasri G Bhat
Date: Tue Jan 12 2016 - 05:26:52 EST
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.
Patches [2] to [4] will add a perf trace point "power:powernv_throttle" and
sysfs throttle counter stats in /sys/devices/system/cpu/cpufreq/chipN.
Patch [1] 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.
Resending the patchset as I has cc'ed stable@xxxxxxxxxxxxxxx in developemnt
cycle and used --in-reply-to to post a new version.
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 (4):
cpufreq: powernv: Remove cpu_to_chip_id() from hot-path
cpufreq: powernv/tracing: Add powernv_throttle tracepoint
cpufreq: powernv: Add a trace print for the throttle event
cpufreq: powernv: Add sysfs attributes to show throttle stats
drivers/cpufreq/powernv-cpufreq.c | 279 +++++++++++++++++++++++++++++++-------
include/trace/events/power.h | 22 +++
kernel/trace/power-traces.c | 1 +
3 files changed, 250 insertions(+), 52 deletions(-)
--
1.9.1