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Wysocki" , Viresh Kumar , Juri Lelli , Steven Rostedt , John Stultz , Dietmar Eggemann , Tim Chen , "Chen, Yu C" , Thomas Gleixner , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Subject: Re: [PATCH v2 09/13] sched/qos: Add rampup multiplier QoS Message-ID: <20260714140809.bs7qimvcvfgk6nha@airbuntu> References: <20260504020003.71306-1-qyousef@layalina.io> <20260504020003.71306-10-qyousef@layalina.io> <20260618083005.1432882-1-soolaugust@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260618083005.1432882-1-soolaugust@gmail.com> On 06/18/26 16:30, zhidao su (Xiaomi) wrote: > Hi Qais, > > I did a bit of testing on an Android device running > 6.18.20-android17 with UTIL_EST and UTIL_EST_RAMPUP_ZERO enabled, and > sched_qos_default_rampup_multiplier=0. > > At the scheduler level, the behaviour looks as expected. With > rampup_multiplier=0, the worker's se.avg.util_est stayed at 0 in my > runs. With rampup_multiplier=4, util_est became non-zero immediately in > the high phase and reached ~1023. > > For end-to-end behaviour, I could not get a useful signal from longer > steady CPU-bound phases. q0 tends to catch up via util_avg quickly, and > the result is very sensitive to the frequency state at the start of the > high phase. > > The clearest signal I saw was with a synthetic low-periodic -> > short-burst native workload: > > low: periodic short work + sleep > high: 5 CPU-bound cycles, no sleep > > Each q0/q4 case was gated to start from <= 940800 kHz on CPU4, and the > worker set and verified the QoS value in the worker thread. > > In that setup, q4 was faster at the 5th high-cycle in 7/8 paired runs. > The larger wins also matched q4 reaching a higher sampled CPU frequency > during the burst, e.g. > > rep3: q0 691200 -> q4 1344000, c5 delta -41.9 ms > rep5: q0 691200 -> q4 3398400, c5 delta -79.2 ms > rep6: q0 691200 -> q4 1344000, c5 delta -91.9 ms > > The main negative case was consistent with the sampled frequency state > too: > > rep1: q0 2083200 -> q4 816000, c5 delta +34.1 ms > > So this is only a synthetic transition-workload data point, but it does > look consistent with the intended periodic-to-busy transition case. I > would not interpret it as a general app benchmark result. > > No Tested-by tag from me for now, since this is not broad performance > validation. Thanks for the running the tests. IIUC, you're reporting that all is good so far.