Re: [PATCH] OMAP CPUIDLE: CPU Idle latency measurement

[Amit Kucheria <amit.kucheria-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>]

On 10 Aug 28, vishwanath.sripathy-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org wrote:
> From: Vishwanath BS <vishwanath.sripathy-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> 
> This patch has instrumentation code for measuring latencies for
> various CPUIdle C states for OMAP. Idea here is to capture the
> timestamp at various phases of CPU Idle and then compute the sw
> latency for various c states. For OMAP, 32k clock is chosen as
> reference clock this as is an always on clock. wkup domain memory
> (scratchpad memory) is used for storing timestamps. One can see the
> worstcase latencies in below sysfs entries (after enabling CONFIG_CPU_IDLE_PROF
> in .config). This information can be used to correctly configure cpu idle
> latencies for various C states after adding HW latencies for each of
> these sw latencies.
> /sys/devices/system/cpu/cpu0/cpuidle/state<n>/actual_latency
> /sys/devices/system/cpu/cpu0/cpuidle/state<n>/sleep_latency
> /sys/devices/system/cpu/cpu0/cpuidle/state<n>/wkup_latency
> 
> THis patch is tested on OMAP ZOOM3 using kevin's pm branch.
> 
> Signed-off-by: Vishwanath BS <vishwanath.sripathy-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> Cc: linaro-dev-cunTk1MwBs8s++Sfvej+rw@public.gmane.org
> ---
>  arch/arm/mach-omap2/cpuidle34xx.c |   58 ++++++++++++++++--
>  arch/arm/mach-omap2/pm.h          |    5 ++
>  arch/arm/mach-omap2/sleep34xx.S   |  121 +++++++++++++++++++++++++++++++++++++
>  drivers/cpuidle/Kconfig           |    5 ++
>  drivers/cpuidle/sysfs.c           |   16 +++++-
>  include/linux/cpuidle.h           |    3 +
>  6 files changed, 202 insertions(+), 6 deletions(-)

Vishwa,

You should perhaps cc Len Brown and LKML for V2 to get acceptance for the new
counters in cpuidle

Regards,
Amit