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Mon, 09 Nov 2026 08:36:22 -0800 (PST) Received: from victus-lab ([193.205.81.5]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4b96cd012e1sm138851295e9.8.2026.11.09.08.36.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Nov 2026 08:36:21 -0800 (PST) From: Yuri Andriaccio To: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Luca Abeni , Yuri Andriaccio Subject: [RFC PATCH v7 01/29] sched/deadline: Introduce dl_freq_invariant flag for fair/ext servers Date: Mon, 9 Nov 2026 17:35:47 +0100 Message-ID: <20261109163616.195264-2-yurand2000@gmail.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261109163616.195264-1-yurand2000@gmail.com> References: <20261109163616.195264-1-yurand2000@gmail.com> 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 Content-Transfer-Encoding: 8bit The fair/ext servers are by design frequency and capacity invariant, i.e. their maximum allowed runtime is fixed, regardless of the frequency the CPU is running. (See also https://lore.kernel.org/all/20250702021440.2594736-1-kuyo.chang@mediatek.com/) This inevitably broke non-fair dl_servers, which would want to instead scale their execution time to be consistent with CBS and GRUB-PA. The newly added flag allows deadline servers to adopt the frequency invariance behaviour as fair/ext servers. Signed-off-by: Yuri Andriaccio --- include/linux/sched.h | 4 ++++ kernel/sched/deadline.c | 5 ++++- 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 1c93da75226e..b78ca828f694 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -706,6 +706,9 @@ struct sched_dl_entity { * contributes to the root domain's total_bw. Only meaningful for server * entities (@dl_server == 1). Allows toggling the reservation on/off * without losing the configured @dl_runtime/@dl_period. + * + * @dl_freq_invariant tells if this server's runtime must NOT be scaled + * by the CPU's frequency and capacity. */ unsigned int dl_throttled : 1; unsigned int dl_yielded : 1; @@ -718,6 +721,7 @@ struct sched_dl_entity { unsigned int dl_defer_running : 1; unsigned int dl_defer_idle : 1; unsigned int dl_bw_attached : 1; + unsigned int dl_freq_invariant : 1; /* * Bandwidth enforcement timer. Each -deadline task has its diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index c0ebdcde5fe5..57c7a8802d8e 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1432,7 +1432,7 @@ static void update_curr_dl_se(struct rq *rq, struct sched_dl_entity *dl_se, s64 return; scaled_delta_exec = delta_exec; - if (!dl_server(dl_se)) + if (!dl_server(dl_se) || !dl_se->dl_freq_invariant) scaled_delta_exec = dl_scaled_delta_exec(rq, dl_se, delta_exec); dl_se->runtime -= scaled_delta_exec; @@ -1862,6 +1862,7 @@ void sched_init_dl_servers(void) dl_se->dl_server = 1; dl_se->dl_defer = 1; + dl_se->dl_freq_invariant = 1; setup_new_dl_entity(dl_se); #ifdef CONFIG_SCHED_CLASS_EXT @@ -1873,6 +1874,7 @@ void sched_init_dl_servers(void) dl_se->dl_server = 1; dl_se->dl_defer = 1; + dl_se->dl_freq_invariant = 1; setup_new_dl_entity(dl_se); /* @@ -3957,6 +3959,7 @@ static void __dl_clear_params(struct sched_dl_entity *dl_se) dl_se->dl_defer = 0; dl_se->dl_defer_running = 0; dl_se->dl_defer_armed = 0; + dl_se->dl_freq_invariant = 0; #ifdef CONFIG_RT_MUTEXES dl_se->pi_se = dl_se; -- 2.56.0