From: Pushpendra Singh <pushpendra.singh@oss.qualcomm.com>
To: Krzysztof Kozlowski <krzk@kernel.org>,
Pushpendra Singh <pussin@qti.qualcomm.com>,
Bjorn Andersson <andersson@kernel.org>,
Konrad Dybcio <konradybcio@kernel.org>
Cc: linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
Shivnandan Kumar <quic_kshivnan@quicinc.com>
Subject: Re: [PATCH v3] soc: qcom: icc-bwmon: Update zone1_thres_count to 3
Date: Tue, 17 Mar 2026 11:15:51 +0530 [thread overview]
Message-ID: <39f51659-134a-49e9-9b44-cd67cfec0dd8@oss.qualcomm.com> (raw)
In-Reply-To: <97890f38-2b17-4591-b5fe-cc0262f944ff@kernel.org>
On 2/28/2026 3:19 PM, Krzysztof Kozlowski wrote:
> On 27/02/2026 12:10, Pushpendra Singh wrote:
>> From: Shivnandan Kumar <quic_kshivnan@quicinc.com>
>>
>> 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
next prev parent reply other threads:[~2026-03-17 5:45 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-27 11:10 [PATCH v3] soc: qcom: icc-bwmon: Update zone1_thres_count to 3 Pushpendra Singh
2026-02-27 19:57 ` Dmitry Baryshkov
2026-02-28 9:49 ` Krzysztof Kozlowski
2026-03-17 5:45 ` Pushpendra Singh [this message]
2026-03-17 7:13 ` Krzysztof Kozlowski
2026-03-17 15:36 ` Dmitry Baryshkov
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