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Tue, 12 Aug 2025 03:17:19 -0700 (PDT) Received: from localhost.localdomain ([2408:80e0:41fc:0:fe29:0:2:4699]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-242ff520192sm14464165ad.90.2025.08.12.03.17.13 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 12 Aug 2025 03:17:18 -0700 (PDT) From: yaozhenguo X-Google-Original-From: yaozhenguo To: mingo@redhat.com, peterz@infradead.org, vincent.guittot@linaro.org Cc: linux-kernel@vger.kernel.org, yaozhenguo@jd.com, ZhenguoYao Subject: [PATCH] sched/fair: Introduce WAKEUP_SELECT_IDLE sched feature Date: Tue, 12 Aug 2025 18:16:50 +0800 Message-Id: <20250812101650.44110-1-yaozhenguo@jd.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) 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-Transfer-Encoding: quoted-printable From: ZhenguoYao Introduce WAKEUP_SELECT_IDLE to control if to select CPU only has SCHED_IDLE task or idle cpu. open it: echo WAKEUP_SELECT_IDLE > /sys/kernel/debug/sched/features close it: echo NO_WAKEUP_SELECT_IDLE > /sys/kernel/debug/sched/features In cloud computing host environments, management and monitoring software are typically configured with SCHED_IDLE priority to avoid interference with normal virtual machine operations. However, if vCPU wakeups consistently select CPU cores running SCHED_IDLE tasks, critical management and monitoring services may fail to execute=E2=80=94even when ot= her idle CPU cores are available in the system. Our servers operate in performance power mode with idle states ( >2=CE=BCs) disabled. Consequently, selecting CPU cores running SCHED_IDLE processes yields minimal benefits while introducing excessive latency for monitoring and management software. Although these processes are low-priority, they are not equivalent to offline processes. To address this, we propose implementing a configurable switch to control whether wakeups may target CPUs executing SCHED_IDLE tasks. More info:https://lore.kernel.org/lkml/cover.1561523542.git.viresh.kumar@li= naro.org/ Signed-off-by: ZhenguoYao --- kernel/sched/fair.c | 5 ++++- kernel/sched/features.h | 2 ++ 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index b173a059315c..2d1629086307 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6781,7 +6781,10 @@ static int sched_idle_rq(struct rq *rq) =20 static int sched_idle_cpu(int cpu) { - return sched_idle_rq(cpu_rq(cpu)); + if (sched_feat(WAKEUP_SELECT_IDLE)) + return sched_idle_rq(cpu_rq(cpu)); + else + return 0; } =20 static void diff --git a/kernel/sched/features.h b/kernel/sched/features.h index 3c12d9f93331..bf23a9dc6e05 100644 --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -63,6 +63,8 @@ SCHED_FEAT(DELAY_ZERO, true) */ SCHED_FEAT(WAKEUP_PREEMPTION, true) =20 +SCHED_FEAT(WAKEUP_SELECT_IDLE, true) + SCHED_FEAT(HRTICK, false) SCHED_FEAT(HRTICK_DL, false) =20 --=20 2.43.5