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SubjectRe: [PATCH] cpufreq: powernv: Redesign the presentation of throttle notification
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On 12/13/2015 12:17 PM, Shilpasri G Bhat wrote:
> Replace the throttling event console messages to perf trace event
> "power:powernv_throttle" and throttle counter stats which are
> exported in sysfs. The newly added sysfs files are as follows:
>
> 1)/sys/devices/system/node/node0/throttle_frequencies
> This gives the throttle stats for each of the available frequencies.
> The throttle stat of a frequency is the total number of times the max
> frequency was reduced to that frequency.
> # cat /sys/devices/system/node/node0/throttle_frequencies
> 4023000 0
> 3990000 0
> 3956000 1
> 3923000 0
> 3890000 0
> 3857000 2
> 3823000 0
> 3790000 0
> 3757000 2
> 3724000 1
> 3690000 1
> ...

Is this data useful? It seems like "elapsed time" at each frequency might be
more useful, if any.

> 2)/sys/devices/system/node/node0/throttle_reasons
> This gives the stats for each of the supported throttle reasons.
> This gives the total number of times the frequency was throttled due
> to each of the reasons.
> # cat /sys/devices/system/node/node0/throttle_reasons
> No throttling 7
> Power Cap 0
> Processor Over Temperature 7
> Power Supply Failure 0
> Over Current 0
> OCC Reset 0
>
> 3)/sys/devices/system/node/node0/throttle_stat
> This gives the total number of throttle events occurred in turbo
> range of frequencies and non-turbo(below nominal) range of
> frequencies.

non-turbo should read "at or below nominal". Maybe "sub-turbo" is a better
term(?)

> # cat /sys/devices/system/node/node0/throttle_stat
> Turbo 7
> Nominal 0

Should this read "Non-turbo" or "Sub-turbo" instead of "Nominal", since the
events could well occur when already operating below nominal.

> Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
> ---
> drivers/cpufreq/powernv-cpufreq.c | 186 +++++++++++++++++++++++++++++---------
> include/trace/events/power.h | 22 +++++
> 2 files changed, 166 insertions(+), 42 deletions(-)
>
> diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
> index cb50138..bdde9d6 100644
> --- a/drivers/cpufreq/powernv-cpufreq.c
> +++ b/drivers/cpufreq/powernv-cpufreq.c
> @@ -28,6 +28,9 @@
> #include <linux/of.h>
> #include <linux/reboot.h>
> #include <linux/slab.h>
> +#include <trace/events/power.h>
> +#include <linux/device.h>
> +#include <linux/node.h>
>
> #include <asm/cputhreads.h>
> #include <asm/firmware.h>
> @@ -43,12 +46,27 @@
> static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
> static bool rebooting, throttled, occ_reset;
>
> +static char throttle_reason[][30] = {
> + "No throttling",
> + "Power Cap",
> + "Processor Over Temperature",
> + "Power Supply Failure",
> + "Over Current",
> + "OCC Reset"
> + };

I'm curious if this would be slightly more efficiently implemented as:
static const char *throttle_reason[] = { ... };

Do you need 30 characters per string for a reason?

Regardless, it should be const.

[...]
--
PC



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