From nobody Wed Dec 17 19:03:22 2025 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 15DA5204F8D; Fri, 14 Mar 2025 20:24:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741983898; cv=none; b=dba9FnSdYwo9tpWCy+IZWiO7fQTNePveQDMlzgceDFyv8u1Gv64Z+Jb1pzlhkUrfQGP5ttG9k2LnKcZi53F6X+NneIVS/XtnHdZA7ebdyTEY8ANJS0LigzpNZPid7PDQ0jZYnOL/Wrsd1b3a6z4VJnbWuz+ij7NVpuSjbmBIpco= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741983898; c=relaxed/simple; bh=p45vM0xMPg/lg4/VXoM5+vmaxs0CEy0qpaTqGyYOnJg=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=cbWhAgYmyueytGF+JGzYIMrdwiE3LjgUuRCdydd348Imfw47RF6sZde3CXwBzFf2aewIOdpCLIOHdEs5JAUwLNwnm/4QkolMxURvKojgO/06HFiiylKaU3uTnZgyuyXo9teKQc7PZEALxzmBqGWgGvA5q/Tps1PDlkHBLcNoC9Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=JMcnU4n2; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=JL13NzfW; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="JMcnU4n2"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="JL13NzfW" Date: Fri, 14 Mar 2025 20:24:53 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1741983894; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ujiLRTsqzxMQjJn8lDFpHGxGGQtx3HwoP9PWymzQrVk=; b=JMcnU4n2nK0Nk2XZDbJrCnrun2S+SzGNqGxBZ21CziJ/A16lXX9Kzkq4ue4bW6cR3XYLT4 iAF/2PjIFpIIwx7FI65hMgeLdPdhTSkLi0VRIsBSH4OZrm97RJuoBnglrRg5UEg9HEszEz CqgNDC7wQW9N9OlzqckBZH2ZKiA0Ny4TL25qrfz/eaINOAmJS7czV1yqqELv/9pYp3rHcl dgtCSeymPvCzI0Ctgf1spK2AkiII5LUwoi1S2nDe+IlfHMhoi5AXES72+nTDSaSYbgab91 oZp35EMyZfa348XEVwYNgwc+7pef1Mhh3/cKwsFP3Q/m5SA/wDTbYA9gmdFuxA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1741983894; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ujiLRTsqzxMQjJn8lDFpHGxGGQtx3HwoP9PWymzQrVk=; b=JL13NzfWc6YG90gkyO1COdx/riuwzGzI7x+FFcDdFZSMYcW2/JRkmyvDRWbNDe2LYVgeUx Q83SZ6AFosPDh+Dw== From: "tip-bot2 for Xuewen Yan" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] sched/uclamp: Add uclamp_is_used() check before enable it Cc: Xuewen Yan , "Peter Zijlstra (Intel)" , Christian Loehle , Vincent Guittot , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20250219093747.2612-2-xuewen.yan@unisoc.com> References: <20250219093747.2612-2-xuewen.yan@unisoc.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <174198389366.14745.13900064422716479622.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the sched/core branch of tip: Commit-ID: 4a14bd0c67d5670844c54356a163aa0ce623dbe1 Gitweb: https://git.kernel.org/tip/4a14bd0c67d5670844c54356a163aa0ce= 623dbe1 Author: Xuewen Yan AuthorDate: Wed, 19 Feb 2025 17:37:47 +08:00 Committer: Peter Zijlstra CommitterDate: Fri, 14 Mar 2025 21:13:19 +01:00 sched/uclamp: Add uclamp_is_used() check before enable it Because the static_branch_enable() would get the cpus_read_lock(), and sometimes users may frequently set the uclamp value of tasks, and this operation would call the static_branch_enable() frequently, so add the uclamp_is_used() check to prevent calling the cpus_read_lock() frequently. And to make the code more concise, add a helper function to encapsulate this and use it everywhere we enable sched_uclamp_used. Signed-off-by: Xuewen Yan Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Christian Loehle Reviewed-by: Vincent Guittot Link: https://lore.kernel.org/r/20250219093747.2612-2-xuewen.yan@unisoc.com --- kernel/sched/core.c | 6 +++--- kernel/sched/sched.h | 14 ++++++++++++++ kernel/sched/syscalls.c | 2 +- 3 files changed, 18 insertions(+), 4 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 45daa41..03d7b63 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1941,12 +1941,12 @@ static int sysctl_sched_uclamp_handler(const struct= ctl_table *table, int write, } =20 if (update_root_tg) { - static_branch_enable(&sched_uclamp_used); + sched_uclamp_enable(); uclamp_update_root_tg(); } =20 if (old_min_rt !=3D sysctl_sched_uclamp_util_min_rt_default) { - static_branch_enable(&sched_uclamp_used); + sched_uclamp_enable(); uclamp_sync_util_min_rt_default(); } =20 @@ -9294,7 +9294,7 @@ static ssize_t cpu_uclamp_write(struct kernfs_open_fi= le *of, char *buf, if (req.ret) return req.ret; =20 - static_branch_enable(&sched_uclamp_used); + sched_uclamp_enable(); =20 guard(mutex)(&uclamp_mutex); guard(rcu)(); diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 8d42d3c..0212a0c 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -3407,6 +3407,18 @@ static inline bool uclamp_is_used(void) return static_branch_likely(&sched_uclamp_used); } =20 +/* + * Enabling static branches would get the cpus_read_lock(), + * check whether uclamp_is_used before enable it to avoid always + * calling cpus_read_lock(). Because we never disable this + * static key once enable it. + */ +static inline void sched_uclamp_enable(void) +{ + if (!uclamp_is_used()) + static_branch_enable(&sched_uclamp_used); +} + static inline unsigned long uclamp_rq_get(struct rq *rq, enum uclamp_id clamp_id) { @@ -3486,6 +3498,8 @@ static inline bool uclamp_is_used(void) return false; } =20 +static inline void sched_uclamp_enable(void) {} + static inline unsigned long uclamp_rq_get(struct rq *rq, enum uclamp_id clamp_id) { diff --git a/kernel/sched/syscalls.c b/kernel/sched/syscalls.c index 9f40348..c326de1 100644 --- a/kernel/sched/syscalls.c +++ b/kernel/sched/syscalls.c @@ -368,7 +368,7 @@ static int uclamp_validate(struct task_struct *p, * blocking operation which obviously cannot be done while holding * scheduler locks. */ - static_branch_enable(&sched_uclamp_used); + sched_uclamp_enable(); =20 return 0; }