From nobody Thu Oct 9 10:48:49 2025 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.12]) (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 36AF22FD899 for ; Wed, 18 Jun 2025 18:22:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.12 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750270924; cv=none; b=rqcnz4lr519vfb2X2M9DeLf5O+erdaRAJSoZ2E9S2odeoi76dMp/OZU1NB58Qjs+uncaH3qLdMqonjZ3kQl6htfGCrXwxMWgW2YZT8y6e/FYDEkDc76bmoSAGQbtAHi6zdd/a0QMbqOAiPFDTuQ/Av7Zd2Z3POZHWg4NK1E6gso= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750270924; c=relaxed/simple; bh=RBEoEDu2A+FwLyh++5jokg1I7TUhNUbkFf08/S4koCY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=u++l74ct5wI88qe+ZhTxahgVxibbraZWIJUXAiGrfYKDyKJFt9lgn/tcRZtplKvjvmasXpdfWkYumF3dDOdoABJmyCFInhfV661Idkc/VE7bFkTegUBPg18Oyk856hhDCaV4uOx+JU6Wj+pkcN21wugnWmWN1myHTXggm5UEej4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=OxZqIyLs; arc=none smtp.client-ip=198.175.65.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="OxZqIyLs" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1750270923; x=1781806923; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=RBEoEDu2A+FwLyh++5jokg1I7TUhNUbkFf08/S4koCY=; b=OxZqIyLsJSroJ2i9MdsrROxH70E3NsG6kvAKifMPTRvyyrGMmXsUYxD3 CPzVxg8vQa7ptoVtXf4Q8V1g+8odAq77fXL+wB1Yz3cOwa5oIFmdnB5YW BortfRVvhpa+xJaYKcO1/iYGTjoGzZlBvQ4DqinF+ijFvIH3FXFHUY7Yw dnqNv+RspKaZf5GkEERusnRttKQTb+Ybdex2YDNmVMcMaLi3YqDVwQEd+ zvko7J7nf4iHqzRFD8LqvQWYwg1aAy+yQ4qBaHEh90PM1XJHSY8jbNW6c NQxsij/EBLJiRtqClKTlBCTYmaEChOOO3OgR1tIMqHZLc+QmYryVKIQJ7 Q==; X-CSE-ConnectionGUID: DbGqwajpS0SQ1kimRCqNOw== X-CSE-MsgGUID: IxguJ0uxQf2FmLjSrT5dxA== X-IronPort-AV: E=McAfee;i="6800,10657,11468"; a="63931707" X-IronPort-AV: E=Sophos;i="6.16,246,1744095600"; d="scan'208";a="63931707" Received: from fmviesa001.fm.intel.com ([10.60.135.141]) by orvoesa104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jun 2025 11:22:02 -0700 X-CSE-ConnectionGUID: 55fSL6zAQZGOckEnYdnVsw== X-CSE-MsgGUID: LUEEbBOqRk6qNZaG5v1xSg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,246,1744095600"; d="scan'208";a="180960148" Received: from b04f130c83f2.jf.intel.com ([10.165.154.98]) by fmviesa001.fm.intel.com with ESMTP; 18 Jun 2025 11:22:02 -0700 From: Tim Chen To: Peter Zijlstra , Ingo Molnar , K Prateek Nayak , "Gautham R . Shenoy" Cc: Tim Chen , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Tim Chen , Vincent Guittot , Libo Chen , Abel Wu , Madadi Vineeth Reddy , Hillf Danton , Len Brown , linux-kernel@vger.kernel.org, Chen Yu Subject: [RFC patch v3 19/20] sched: Introduce SCHED_CACHE_LB to control cache aware load balance Date: Wed, 18 Jun 2025 11:28:07 -0700 Message-Id: X-Mailer: git-send-email 2.32.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Introduce the SCHED_CACHE_LB sched feature to enable or disable cache aware load balance in the schduler. Co-developed-by: Chen Yu Signed-off-by: Tim Chen --- kernel/sched/fair.c | 18 ++++++++++-------- kernel/sched/features.h | 1 + 2 files changed, 11 insertions(+), 8 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e342524481ed..af742601f2d7 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9982,7 +9982,7 @@ int can_migrate_task(struct task_struct *p, struct lb= _env *env) return 1; =20 #ifdef CONFIG_SCHED_CACHE - if (sched_feat(SCHED_CACHE) && + if (sched_feat(SCHED_CACHE) && sched_feat(SCHED_CACHE_LB) && get_migrate_hint(env->src_cpu, env->dst_cpu, p) =3D=3D mig_forbid) return 0; #endif @@ -10068,7 +10068,7 @@ static struct list_head LIST_HEAD(no_pref_llc); LIST_HEAD(pref_other_llc); =20 - if (!sched_feat(SCHED_CACHE)) + if (!sched_feat(SCHED_CACHE) || !sched_feat(SCHED_CACHE_LB)) return tasks; =20 if (cpus_share_cache(env->dst_cpu, env->src_cpu)) @@ -10253,7 +10253,8 @@ static int detach_tasks(struct lb_env *env) * The tasks have already been sorted by order_tasks_by_llc(), * they are tasks that prefer the current LLC. */ - if (sched_feat(SCHED_CACHE) && p->preferred_llc !=3D -1 && + if (sched_feat(SCHED_CACHE) && sched_feat(SCHED_CACHE_LB) && + p->preferred_llc !=3D -1 && llc_id(env->src_cpu) =3D=3D p->preferred_llc) break; #endif @@ -10910,7 +10911,7 @@ static inline bool llc_balance(struct lb_env *env, = struct sg_lb_stats *sgs, struct sched_domain *child =3D env->sd->child; int llc; =20 - if (!sched_feat(SCHED_CACHE)) + if (!sched_feat(SCHED_CACHE) || !sched_feat(SCHED_CACHE_LB)) return false; =20 if (env->sd->flags & SD_SHARE_LLC) @@ -11021,7 +11022,8 @@ static void update_sg_if_llc(struct lb_env *env, st= ruct sg_lb_stats *sgs, struct sched_domain *sd =3D env->sd->child; struct sched_domain_shared *sd_share; =20 - if (!sched_feat(SCHED_CACHE) || env->idle =3D=3D CPU_NEWLY_IDLE) + if (!sched_feat(SCHED_CACHE) || env->idle =3D=3D CPU_NEWLY_IDLE || + !sched_feat(SCHED_CACHE_LB)) return; =20 /* only care the sched domain that spans 1 LLC */ @@ -11083,7 +11085,7 @@ static inline void update_sg_lb_stats(struct lb_env= *env, *sg_overutilized =3D 1; =20 #ifdef CONFIG_SCHED_CACHE - if (sched_feat(SCHED_CACHE)) { + if (sched_feat(SCHED_CACHE) && sched_feat(SCHED_CACHE_LB)) { int j; =20 for (j =3D 0; j < max_llcs; ++j) @@ -12368,7 +12370,7 @@ imbalanced_active_balance(struct lb_env *env) static inline bool break_llc_locality(struct lb_env *env) { - if (!sched_feat(SCHED_CACHE)) + if (!sched_feat(SCHED_CACHE) || !sched_feat(SCHED_CACHE_LB)) return 0; =20 if (cpus_share_cache(env->src_cpu, env->dst_cpu)) @@ -12870,7 +12872,7 @@ static int active_load_balance_cpu_stop(void *data) #ifdef CONFIG_SCHED_CACHE int llc =3D llc_idx(target_cpu); =20 - if (!sched_feat(SCHED_CACHE)) + if (!sched_feat(SCHED_CACHE) || !sched_feat(SCHED_CACHE_LB)) goto out_unlock; =20 if (llc < 0) diff --git a/kernel/sched/features.h b/kernel/sched/features.h index d2af7bfd36bf..11dbd74cd365 100644 --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -88,6 +88,7 @@ SCHED_FEAT(TTWU_QUEUE, true) SCHED_FEAT(SIS_UTIL, true) =20 SCHED_FEAT(SCHED_CACHE, true) +SCHED_FEAT(SCHED_CACHE_LB, true) /* * Issue a WARN when we do multiple update_rq_clock() calls * in a single rq->lock section. Default disabled because the --=20 2.32.0