Re: [PATCH v3] soc: qcom: icc-bwmon: Update zone1_thres_count to 3

[Pushpendra Singh]

On 2/28/2026 3:19 PM, Krzysztof Kozlowski wrote:
> On 27/02/2026 12:10, Pushpendra Singh wrote:
>> From: Shivnandan Kumar <quic_kshivnan@xxxxxxxxxxx>
>>
>> Reduce zone1_thres_count from 16 to 3 so the driver can lower the bus
>> vote after 3 sample windows instead of waiting for 16. The previous
>> 16‑window delay (~64 ms) is too long at higher FPS workloads,
>> causing delayed decision making and measurable power regression.
>>
>> Empirical tuning showed that lower values (e.g., 2) made bwmon behavior
>> jittery, while higher values (4–6) were stable but less responsive and
>> reduced power savings. A value of 3 provided the best balance: responsive
>> enough for timely power reduction while maintaining stable bwmon
>> operation.
>>
>> Significant power savings were observed across multiple use cases when
>> reducing the threshold from 16 to 3:
>>
>> USECASE			zone1_thres_count=16     zone1_thres_count=3
>> 4K video playback	   236.15 mA                  203.15 mA
>> Sleep			    7mA			        6.9mA
>> Display (idle display)	  71.95mA			67.11mA
> Which hardware exactly? Which kernel?
>
> You keep running this on downstream, like a lot of code from Qualcomm
> and speeches on conferences, so I just don't trust the numbers.

The numbers presented were obtained on then upstream 6.6 based kernels across multiple SoCs (sc7280/sa8775p).
Also, please suggest benchmarks and other perf level measurements done when the number 16 was chosen initially,
that way we can ensure there is no regression.

Regards,
Pushpendra Singh

>
> Best regards,
> Krzysztof