Re: [PATCH 0/2] cpuidle: idle_miss accounting fixes

[Christian Loehle <christian.loehle@arm.com>]

On 10/30/26 08:36, Christian Loehle wrote:
> These two fixes exclude timer-broadcast fallbacks from governor miss
> accounting and respect the entry-time latency constraint when looking for
> a better deeper state.
> No functional change outside of sysfs above/below and tracing.
> 
> Patch 1: Exclude timer-broadcast fallbacks
> 
> When tick_broadcast_enter() fails, the core forces a shallower state.
> Exclude these entries from governor miss accounting while retaining
> residency, usage and governor feedback.
> 
> On Orion O6, traces with menu and TEO running schbench, tbench and hackbench
> recorded 6930 cpu_idle_miss events on 8172 broadcast fallbacks before the
> fix, and none on 7763 fallbacks with patch 1. All matched fallbacks entered
> WFI.
> 
> Patch 2: Respect latency constraints for below misses
> 
> An enabled deeper state may violate the latency QoS constraint, causing a
> false below miss. Save the governor latency limit at entry and exclude
> states exceeding it, without an additional state-table walk. Disable flags
> continue to be checked at exit as they are expected to change less frequently.
> 
> Christian Loehle (2):
>   cpuidle: Skip miss accounting for timer broadcast fallbacks
>   cpuidle: Respect latency constraints when accounting below misses
> 
>  drivers/cpuidle/cpuidle.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
> 

Rafael, any opinions?