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[82.212.34.85]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-458b3664e3esm26052706f8f.3.2026.05.13.08.09.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 May 2026 08:09:25 -0700 (PDT) Date: Wed, 13 May 2026 17:09:25 +0200 Message-ID: <7a4f4e3f4caea5cac2a2b7b5994a97ee.tomge68@gmail.com> From: Tom Gebhardt To: Qais Yousef Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , Vincent Guittot Subject: Re: [PATCH v2 00/13] sched/fair/schedutil: Better manage system response time In-Reply-To: <20260504020003.71306-1-qyousef@layalina.io> References: <20260504020003.71306-1-qyousef@layalina.io> Content-Type: text/plain; charset=utf-8 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Hi Qais, I tested your v2 12/13 (sched/fair: Call update_util_est() after dequeue_entities()) and RFC 13/13 (sched/pelt: Always allow load updates) on ARM (Raspberry Pi 5, Cortex-A76, 4-core), combined with Peter Zijlstra's ttwu series (rebased to 7.0.y by marioroy). Both patches applied cleanly on top of rpi-7.0.y + 10 ttwu patches without conflicts. Results using stress-ng 0.15.06 pipe stressor (4 workers, 20s): Kernel Clock pipe bogo ops/s D vs. 6.6 ---------------------------------- --------- ---------------- ---------- 6.6.78-v8-16k+ 2800 MHz 2 487 746 +/-0% (ref) 7.0.0-v8-16k+ stock 2400 MHz 1 694 011 -31.9% 7.0.0-v8-16k+ stock 2800 MHz 1 851 567 -25.6% 7.0.0 + ttwu only (10 patches) 2400 MHz 1 836 006 -26.2% 7.0.0 + ttwu only (10 patches) 2800 MHz 1 934 076 -22.3% 7.0.0 + ttwu + your 2 Qais patches 2400 MHz 1 996 002 -19.8% 7.0.0 + ttwu + your 2 Qais patches 2800 MHz 2 342 144 -5.9% The ttwu-only set recovers ~3-4% of the regression on ARM. Adding your two patches brings a much larger improvement -- especially under overclocking, where the combined set recovers roughly 94% of the 6.6 baseline. The remaining ~6% gap may be related to ARM-specific DELAY_DEQUEUE interactions. Device: Raspberry Pi 5 (8 GB, C1-stepping), Bookworm arm64, rpi-7.0.y. Background: https://github.com/raspberrypi/linux/issues/7308 Thanks for the series -- the ARM results look very promising. Tom