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Wed, 04 Nov 2026 23:46:22 -0800 (PST) Received: from [10.218.26.184] ([202.46.22.19]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cdb4693fef8sm1887983a12.17.2026.11.04.23.46.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Nov 2026 23:46:21 -0800 (PST) Message-ID: <14d9e262-c3e6-41b4-a408-3d12185b0d48@oss.qualcomm.com> Date: Thu, 5 Nov 2026 13:16:17 +0530 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] soc: qcom: icc-bwmon: Update zone1_thres_count to 3 To: Konrad Dybcio , Krzysztof Kozlowski , Bjorn Andersson , Konrad Dybcio Cc: linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260227111051.1789439-1-pussin@qti.qualcomm.com> <7a92ca6c-cc66-486f-b297-cb2907e1c0e6@oss.qualcomm.com> Content-Language: en-US From: Pushpendra Singh In-Reply-To: <7a92ca6c-cc66-486f-b297-cb2907e1c0e6@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Proofpoint-Spam-Info: AW1haW4tMjYxMTA1MDAzMCBTYWx0ZWRfX88epHQftFFjC T+/cHId7SqRZZsTGjE5CVoNQwjLQz4Lj6Jn2VYLJbuzBjjJQMZrXSa2wcYWG+MxbaUFtQQe3SNQ zYM7Okc+720QVF8UeCTwz3EVnfugp0Q= X-Proofpoint-ORIG-GUID: C1U5Po61TkeaGbrpUNY2qtOnEzKCvZSz X-Authority-Analysis: v=2.4 cv=P/6vFSAu c=1 sm=1 tr=0 ts=6aec344f cx=c_pps a=mDZGXZTwRPZaeRUbqKGCBw==:117 a=fChuTYTh2wq5r3m49p7fHw==:17 a=IkcTkHD0fZMA:10 a=zJRp6_cAMcgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=ZpdpYltYx_vBUK5n70dp:22 a=COk6AnOGAAAA:8 a=EUspDBNiAAAA:8 a=4pBTPSVEyfT0CdRydYkA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=zc0IvFSfCIW2DFIPzwfm:22 a=TjNXssC_j7lpFel5tvFf:22 X-Proofpoint-GUID: C1U5Po61TkeaGbrpUNY2qtOnEzKCvZSz X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMTA1MDAzMCBTYWx0ZWRfX+YhX15n9eFjT f6o04C3Sy3YzyMSrLzxvnDh3fr+jvEmo/aePlXs0zSGQX4QGGkmruJzZbID7xNY8cQzlmcswH5B NgPCUJTmRhtuQp7lCeaE684FCVsR3ZzWbkwGH/06ox+OpeFzdb8h23RddxH9uJlLYBLSZj84TdK dFqt9/56sbiiQnB6fDcFzmN0Du9VFy2F+QQLam8S2FkqOBXRQGD+XAnzfegCC4NhoxExkbLKEKE O7fRdqKPfgVFqWNruF8vWDg1FCpYnJBZTRC95mcW4Yp0Vlo6RuiqfD9PfkqAda9vGy35PeQnVKF GziLQ8NIsvmPPBtxGUbU2g/wmuAhWR86TQyurIHS+3CMAmrqQjENIKZQrrGs7XD34QSgH7nRZUe 2MK3YhdQQJKLL1CR1gFKbt0Lp6A7Yb+gdfdiz/duqECBJV8Xe66nAY2P9vWI+9aGxDHMp+cUKQz ssq62OmwCQE+/gU/vEA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.138,FMLib:17.12.100.49 definitions=2026-11-05_02,2026-11-04_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 suspectscore=0 adultscore=0 bulkscore=0 malwarescore=0 phishscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610300000 definitions=main-2611050030 On 6/16/2026 5:09 PM, Konrad Dybcio wrote: > On 2/27/26 12:10 PM, Pushpendra Singh wrote: >> From: Shivnandan Kumar >> >> 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 >> >> Signed-off-by: Shivnandan Kumar >> Signed-off-by: Pushpendra Singh >> --- > > Since this patch does not seem to be moving on its own, I will gladly > hijack the discussion.. > > I was wondering if we could transplant the bwmon devfreq+governor+memlat > setup from downstream. It seems to be way "smarter", in the sense that > it keeps some hysteresis information, unlike icc-bwmon, which is purely > reactive to immediate signals, in addition to (in my brief understanding) > sampling other data sources, such as the PMU > Thanks for the suggestion.The downstream solution explores a broader policy space with additional inputs and hysteresis. It is an interesting direction, though evaluating such an approach would likely be a separate discussion. For this series, we are focusing on a small tuning of the existing icc-bwmon behavior. Based on our latest validation, reducing zone1_thres_count improves responsiveness to decreasing bandwidth demand, allowing DDR and LLCC votes to be reduced sooner and resulting in measurable power savings. Thanks, Pushpendra