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

[Dmitry Baryshkov]

On Tue, Mar 17, 2026 at 11:15:51AM +0530, Pushpendra Singh wrote:
> 
> 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).

Please don't use old kernels for upstream work.

> 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.
> 
-- 
With best wishes
Dmitry