From nobody Mon Dec 1 21:31:22 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7E39D10F1 for ; Mon, 1 Dec 2025 06:47:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764571625; cv=none; b=XOu5B7Z6YqNGVD0UqhgxNmb58W8BcPlMv94FexbvNelcOieb5d/9RB98ajSCs8Wb3/6SLzQyKveJX64Zo3lM9oWDFURAvbaYTHXvBIO7X070YAd/waH7VGQGS0+Kgwt6MoIdnQTcJBrgZtFe4eKHlf10Jx44Gofsvt5u6Oai3R8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764571625; c=relaxed/simple; bh=d6KM/uAc3610WrsLA2cfidg91+4iq0j2UQnvFJ8L8Dg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XizzfGxvMclguYPECgvdIREVXLPkxqzVQwtfjU0lqS4eLz4QsTbetLjwfPx5+0LkKMmuHxzV+brQMVtCD6Jvi2o7aDUwI+vQXixdNUDkgXna+Px1TmHy/SgdQVC14dwn2tv2j9U0Q0a6B9dNLnf10rrtQhPU2TmJhlXzmXIh+dA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qNFQ0cvI; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="qNFQ0cvI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 49E3FC116D0; Mon, 1 Dec 2025 06:47:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764571625; bh=d6KM/uAc3610WrsLA2cfidg91+4iq0j2UQnvFJ8L8Dg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qNFQ0cvIZUsXuPE/Tfvw4X+ecwAmvbxBQ4L71/JpQX4cUKxfIY2PrA00qZj6BNXFG rLzEtkSh6aLzQGUAnLPgOijP03evdpSO7hvXiodbUX1X82KReMigHWKI0SzGoYLWjc T7iHM/bndXNge4MkIckDr0wEr8m64oon6+6HCo6BqXKZRCEjtYWyICvA18QS9Log3R naFSrAtQO4BGqNRjmbobt8vf1V8RAVZwlBhak26h+SMHR7Jkdbc1uz5uXNOiHFXJON hEzMIY39eepAb2Fi+kO50wU1/kK44arqJNf2j7zuzPBPOFasqjYBRinm9Bj2re0oaw 8wDOgIpD0vm1g== From: Ingo Molnar To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Juri Lelli , Dietmar Eggemann , Valentin Schneider , Vincent Guittot , Shrikanth Hegde , Linus Torvalds , Mel Gorman , Steven Rostedt , Thomas Gleixner , Ingo Molnar Subject: [PATCH 1/6] sched/fair: Join two #ifdef CONFIG_CFS_BANDWIDTH blocks Date: Mon, 1 Dec 2025 07:46:42 +0100 Message-ID: <20251201064647.1851919-2-mingo@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251201064647.1851919-1-mingo@kernel.org> References: <20251201064647.1851919-1-mingo@kernel.org> 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" Join two identical #ifdef blocks: #ifdef CONFIG_CFS_BANDWIDTH ... #endif #ifdef CONFIG_CFS_BANDWIDTH ... #endif Also mark nested #ifdef blocks in the usual fashion, to make it more apparent where in a nested hierarchy of #ifdefs we are at a glance. Signed-off-by: Ingo Molnar --- kernel/sched/sched.h | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index b419a4d98461..a29965c93832 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -726,9 +726,7 @@ struct cfs_rq { unsigned long h_load; u64 last_h_load_update; struct sched_entity *h_load_next; -#endif /* CONFIG_FAIR_GROUP_SCHED */ =20 -#ifdef CONFIG_FAIR_GROUP_SCHED struct rq *rq; /* CPU runqueue to which this cfs_rq is attached */ =20 /* @@ -746,14 +744,14 @@ struct cfs_rq { /* Locally cached copy of our task_group's idle value */ int idle; =20 -#ifdef CONFIG_CFS_BANDWIDTH +# ifdef CONFIG_CFS_BANDWIDTH int runtime_enabled; s64 runtime_remaining; =20 u64 throttled_pelt_idle; -#ifndef CONFIG_64BIT +# ifndef CONFIG_64BIT u64 throttled_pelt_idle_copy; -#endif +# endif u64 throttled_clock; u64 throttled_clock_pelt; u64 throttled_clock_pelt_time; @@ -765,7 +763,7 @@ struct cfs_rq { struct list_head throttled_list; struct list_head throttled_csd_list; struct list_head throttled_limbo_list; -#endif /* CONFIG_CFS_BANDWIDTH */ +# endif /* CONFIG_CFS_BANDWIDTH */ #endif /* CONFIG_FAIR_GROUP_SCHED */ }; =20 --=20 2.51.0 From nobody Mon Dec 1 21:31:22 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 B24C0287265 for ; Mon, 1 Dec 2025 06:47:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764571628; cv=none; b=EJwow/EZ7UKNCRal6Ig7Yw8bzKKFGCPj/WrB+9NiDbuvyoj59wJHCfElfgXsdC9MerSGFXd1ur7fxppI9hMzECQYZ/+pWZrqcC2EWN0x7vZ1gdy5oiyDSXtAt5tK7MfOS2A5oTLZSM+2qyZe31LSDotjpNgmjcjv/pZoIMYVSXU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764571628; c=relaxed/simple; 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charset="utf-8" - Fix vertical alignment - Fix typos - Fix capitalization Signed-off-by: Ingo Molnar --- kernel/sched/sched.h | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index a29965c93832..6bfcf52a4840 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -670,13 +670,13 @@ struct balance_callback { void (*func)(struct rq *rq); }; =20 -/* CFS-related fields in a runqueue */ +/* Fair scheduling SCHED_{NORMAL,BATCH,IDLE} related fields in a runqueue:= */ struct cfs_rq { struct load_weight load; unsigned int nr_queued; - unsigned int h_nr_queued; /* SCHED_{NORMAL,BATCH,IDLE} */ - unsigned int h_nr_runnable; /* SCHED_{NORMAL,BATCH,IDLE} */ - unsigned int h_nr_idle; /* SCHED_IDLE */ + unsigned int h_nr_queued; /* SCHED_{NORMAL,BATCH,IDLE} */ + unsigned int h_nr_runnable; /* SCHED_{NORMAL,BATCH,IDLE} */ + unsigned int h_nr_idle; /* SCHED_IDLE */ =20 s64 avg_vruntime; u64 avg_load; @@ -690,7 +690,7 @@ struct cfs_rq { struct rb_root_cached tasks_timeline; =20 /* - * 'curr' points to currently running entity on this cfs_rq. + * 'curr' points to the currently running entity on this cfs_rq. * It is set to NULL otherwise (i.e when none are currently running). */ struct sched_entity *curr; @@ -739,7 +739,7 @@ struct cfs_rq { */ int on_list; struct list_head leaf_cfs_rq_list; - struct task_group *tg; /* group that "owns" this runqueue */ + struct task_group *tg; /* Group that "owns" this runqueue */ =20 /* Locally cached copy of our task_group's idle value */ int idle; --=20 2.51.0 From nobody Mon Dec 1 21:31:22 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 088922882D0 for ; Mon, 1 Dec 2025 06:47:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; 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Mon, 1 Dec 2025 06:47:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764571631; bh=DfkWEaS9UJl5Sj94t+cKEg8dzhqlJYuTvalTnXM+88M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=N0yXXjQH+ScAGrFdxkiCzHzz190bwXR6Ytwoz6qj82dcOalrnC1vejYCQLHRtS+nB HFR03S6a/pBY7mFaoRIlAHkdYrKf/kXGClFljoWznDgCLlHO0J67mEZJ6ztdyI/GRj pttEMIRBRgPkV68g/kQwtOvWP1VFJore2uW8AKEscVKFhsBDIcBCVjRdpluMejhNX9 Q/dorg6wlHGzs14xLpXbmBawI5cMGmNJ+IoA5W1rNeazhOf4F/otogoPNqZjHJjkSl JibxYJ/s6NGmIW/WAozqf3a9mFwfLD+L9TG7LrxGdt/G7dYYUawbBm5y7yqYF1UHAK d2sCMYl5hBsAg== From: Ingo Molnar To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Juri Lelli , Dietmar Eggemann , Valentin Schneider , Vincent Guittot , Shrikanth Hegde , Linus Torvalds , Mel Gorman , Steven Rostedt , Thomas Gleixner , Ingo Molnar Subject: [PATCH 3/6] sched/fair: Separate se->vlag from se->vprot Date: Mon, 1 Dec 2025 07:46:44 +0100 Message-ID: <20251201064647.1851919-4-mingo@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251201064647.1851919-1-mingo@kernel.org> References: <20251201064647.1851919-1-mingo@kernel.org> 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" There's no real space concerns here and keeping these fields in a union makes reading (and tracing) the scheduler code harder. Signed-off-by: Ingo Molnar --- include/linux/sched.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index e84bc5bce816..667fa08aee75 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -586,7 +586,7 @@ struct sched_entity { u64 sum_exec_runtime; u64 prev_sum_exec_runtime; u64 vruntime; - union { +// union { /* * When !@on_rq this field is vlag. * When cfs_rq->curr =3D=3D se (which implies @on_rq) @@ -594,7 +594,7 @@ struct sched_entity { */ s64 vlag; u64 vprot; - }; +// }; u64 slice; =20 u64 nr_migrations; --=20 2.51.0 From nobody Mon Dec 1 21:31:22 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 303572882D0 for ; Mon, 1 Dec 2025 06:47:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764571635; cv=none; b=FVxLOdAYUoImk/D0gdYR4ZyWfToN7q4x8Yg+4AanPaVwySqRyMtQKjg+dTNsmttXG6sk4WlxOys/QFJiZUN1W9aboKZ+zZ8CW6L4yg7zfRefAqxM9BiwSksoI1ugm4aPyUxKItuxtslGdSzqkyl87EzsO49o3wOc5FkdX4cYLHw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764571635; c=relaxed/simple; bh=1/FV31VI7KXAOzhNf02k0IfeyAjELjSFOs2YkzShm+Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pjf1rkTnvYNLIP0JX7z5iJjcSO5aGRiqVfB9x7dnFOT9YD70P0eTrQ2+BUJKFNhU17ZGrAgU9pnGc8JqVSfzViXF96NJBez1tAYjrx9KXDjZVLnQIqHf35ILoMdxk1hf8M37f6N7AeyVOiqTPd70UgcwGJNKgeLCRN9hv9jbDTU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JH7AZvsV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JH7AZvsV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F2E06C116C6; Mon, 1 Dec 2025 06:47:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764571634; bh=1/FV31VI7KXAOzhNf02k0IfeyAjELjSFOs2YkzShm+Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JH7AZvsVgYhyl/YPl1NonwN+62uiEDIDT9VGySJXOkOZnWyQOtXH1iwNOBxnhBTkn 1C84JAFgjOlz8pPZHOb9KiI+YriuiKs09NFOabrf1E8xnytJ/rieOTDdGK5FXR0xrO ppDBjVVkMjSbOCiNmJPN4pcHtkQa7N9jZcegtw8WPa1OrnIqCcGibL19vfTAcleAc1 kZvf8EaUjhZLUs3Y6Ycnp4roT71gv7xyHw5OJbwmZuIDhNup9SWQlfew/UuXEgE9V6 S5Rx54m2keaW3Hc6VCX4ustfPMPYOh8cyWazdJJN65KD0WKh9ScuNTPsfUBWd8UiIv A2ywhAo/UmhHQ== From: Ingo Molnar To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Juri Lelli , Dietmar Eggemann , Valentin Schneider , Vincent Guittot , Shrikanth Hegde , Linus Torvalds , Mel Gorman , Steven Rostedt , Thomas Gleixner , Ingo Molnar Subject: [PATCH 4/6] sched/fair: Rename avg_vruntime() to cfs_avg_vruntime() Date: Mon, 1 Dec 2025 07:46:45 +0100 Message-ID: <20251201064647.1851919-5-mingo@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251201064647.1851919-1-mingo@kernel.org> References: <20251201064647.1851919-1-mingo@kernel.org> 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" Since the unit of the ->avg_vruntime field isn't actually the same thing as the avg_vruntime() result, reduce confusion and rename the latter to the common cfs_*() nomenclature of visible global functions of the fair scheduler. Signed-off-by: Ingo Molnar --- kernel/sched/debug.c | 2 +- kernel/sched/fair.c | 10 +++++----- kernel/sched/sched.h | 2 +- 3 files changed, 7 insertions(+), 7 deletions(-) diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 41caa22e0680..a6ceda12bd35 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -829,7 +829,7 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct c= fs_rq *cfs_rq) SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "zero_vruntime", SPLIT_NS(zero_vruntime)); SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "avg_vruntime", - SPLIT_NS(avg_vruntime(cfs_rq))); + SPLIT_NS(cfs_avg_vruntime(cfs_rq))); SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "right_vruntime", SPLIT_NS(right_vruntime)); spread =3D right_vruntime - left_vruntime; diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 769d7b7990df..3d6d551168aa 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -651,7 +651,7 @@ void avg_vruntime_update(struct cfs_rq *cfs_rq, s64 del= ta) * Specifically: avg_runtime() + 0 must result in entity_eligible() :=3D t= rue * For this to be so, the result of this function must have a left bias. */ -u64 avg_vruntime(struct cfs_rq *cfs_rq) +u64 cfs_avg_vruntime(struct cfs_rq *cfs_rq) { struct sched_entity *curr =3D cfs_rq->curr; s64 avg =3D cfs_rq->avg_vruntime; @@ -696,7 +696,7 @@ static void update_entity_lag(struct cfs_rq *cfs_rq, st= ruct sched_entity *se) =20 WARN_ON_ONCE(!se->on_rq); =20 - vlag =3D avg_vruntime(cfs_rq) - se->vruntime; + vlag =3D cfs_avg_vruntime(cfs_rq) - se->vruntime; limit =3D calc_delta_fair(max_t(u64, 2*se->slice, TICK_NSEC), se); =20 se->vlag =3D clamp(vlag, -limit, limit); @@ -716,7 +716,7 @@ static void update_entity_lag(struct cfs_rq *cfs_rq, st= ruct sched_entity *se) * * lag_i >=3D 0 -> \Sum (v_i - v)*w_i >=3D (v_i - v)*(\Sum w_i) * - * Note: using 'avg_vruntime() > se->vruntime' is inaccurate due + * Note: using 'cfs_avg_vruntime() > se->vruntime' is inaccurate due * to the loss in precision caused by the division. */ static int vruntime_eligible(struct cfs_rq *cfs_rq, u64 vruntime) @@ -742,7 +742,7 @@ int entity_eligible(struct cfs_rq *cfs_rq, struct sched= _entity *se) =20 static void update_zero_vruntime(struct cfs_rq *cfs_rq) { - u64 vruntime =3D avg_vruntime(cfs_rq); + u64 vruntime =3D cfs_avg_vruntime(cfs_rq); s64 delta =3D (s64)(vruntime - cfs_rq->zero_vruntime); =20 avg_vruntime_update(cfs_rq, delta); @@ -5099,7 +5099,7 @@ void __setparam_fair(struct task_struct *p, const str= uct sched_attr *attr) static void place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) { - u64 vslice, vruntime =3D avg_vruntime(cfs_rq); + u64 vslice, vruntime =3D cfs_avg_vruntime(cfs_rq); s64 lag =3D 0; =20 if (!se->custom_slice) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 6bfcf52a4840..47f7b6df634c 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -3956,7 +3956,7 @@ static inline void task_tick_mm_cid(struct rq *rq, st= ruct task_struct *curr) { } static inline void init_sched_mm_cid(struct task_struct *t) { } #endif /* !CONFIG_SCHED_MM_CID */ =20 -extern u64 avg_vruntime(struct cfs_rq *cfs_rq); +extern u64 cfs_avg_vruntime(struct cfs_rq *cfs_rq); extern int entity_eligible(struct cfs_rq *cfs_rq, struct sched_entity *se); static inline void move_queued_task_locked(struct rq *src_rq, struct rq *dst_rq, struct = task_struct *task) --=20 2.51.0 From nobody Mon Dec 1 21:31:22 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 152E628C00C for ; 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dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CxiUcpU+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 35E78C116D0; Mon, 1 Dec 2025 06:47:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764571638; bh=bxmMoilf/XYowX5IImYa/h2tk2jPbflYVNMP1QhqnwM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CxiUcpU+HBY2nRfFjmB+wkuDgUClRuKJLox7CBphfuoqPJ3/Mtf7dib7D4N6MKlNI Z4+3Ek/Rc7bJtA2986l8MazGKIvhlX/jwvPdqGdJ7gwjIw2K+wCbRIspkxgustBJAG dyVnrU5eCLoHrNrvgh83rezQpv2T5VOe2dinlCPgJJCWIyOy2OnaJnA6XbDETVGmMe Gg5rFN5jKRbbKmPQogPH0v6twqZkHkA9ZRmrVOX06R+ZqFkFK5NQ2fKrCBT0wTYlbx KAAy6VOyIjsCVSV+LC1RwsULeesX9tV8aEz/FRVibTRdA5jc7D2avRGppU81f2pEer /6EhPKqR8pgsg== From: Ingo Molnar To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Juri Lelli , Dietmar Eggemann , Valentin Schneider , Vincent Guittot , Shrikanth Hegde , Linus Torvalds , Mel Gorman , Steven Rostedt , Thomas Gleixner , Ingo Molnar Subject: [PATCH 5/6] sched/fair: Rename cfs_rq::avg_load to cfs_rq::sum_weight Date: Mon, 1 Dec 2025 07:46:46 +0100 Message-ID: <20251201064647.1851919-6-mingo@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251201064647.1851919-1-mingo@kernel.org> References: <20251201064647.1851919-1-mingo@kernel.org> 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" The ::avg_load field is a long-standing misnomer: it says it's an 'average load', but in reality it's the momentary sum of the load of all currently runnable tasks. We'd have to also perform a division by nr_running (or use time-decay) to arrive at any sort of average value. This is clear from comments about the math of fair scheduling: * \Sum w_i :=3D cfs_rq->avg_load The sum of all weights is ... the sum of all weights, not the average of all weights. To make it doubly confusing, there's also an ::avg_load in the load-balancing struct sg_lb_stats, which *is* a true average. The second part of the field's name is a minor misnomer as well: it says 'load', and it is indeed a load_weight structure as it shares code with the load-balancer - but it's only in an SMP load-balancing context where load =3D weight, in the fair scheduling context the primary purpose is the weighting of different nice levels. So rename the field to ::sum_weight instead, which makes the terminology of the EEVDF math match up with our implementation of it: * \Sum w_i :=3D cfs_rq->sum_weight Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 16 ++++++++-------- kernel/sched/sched.h | 2 +- 2 files changed, 9 insertions(+), 9 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 3d6d551168aa..2ffd52a2e7a0 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -608,7 +608,7 @@ static inline s64 entity_key(struct cfs_rq *cfs_rq, str= uct sched_entity *se) * * v0 :=3D cfs_rq->zero_vruntime * \Sum (v_i - v0) * w_i :=3D cfs_rq->avg_vruntime - * \Sum w_i :=3D cfs_rq->avg_load + * \Sum w_i :=3D cfs_rq->sum_weight * * Since zero_vruntime closely tracks the per-task service, these * deltas: (v_i - v), will be in the order of the maximal (virtual) lag @@ -625,7 +625,7 @@ avg_vruntime_add(struct cfs_rq *cfs_rq, struct sched_en= tity *se) s64 key =3D entity_key(cfs_rq, se); =20 cfs_rq->avg_vruntime +=3D key * weight; - cfs_rq->avg_load +=3D weight; + cfs_rq->sum_weight +=3D weight; } =20 static void @@ -635,16 +635,16 @@ avg_vruntime_sub(struct cfs_rq *cfs_rq, struct sched_= entity *se) s64 key =3D entity_key(cfs_rq, se); =20 cfs_rq->avg_vruntime -=3D key * weight; - cfs_rq->avg_load -=3D weight; + cfs_rq->sum_weight -=3D weight; } =20 static inline void avg_vruntime_update(struct cfs_rq *cfs_rq, s64 delta) { /* - * v' =3D v + d =3D=3D> avg_vruntime' =3D avg_runtime - d*avg_load + * v' =3D v + d =3D=3D> avg_vruntime' =3D avg_runtime - d*sum_weight */ - cfs_rq->avg_vruntime -=3D cfs_rq->avg_load * delta; + cfs_rq->avg_vruntime -=3D cfs_rq->sum_weight * delta; } =20 /* @@ -655,7 +655,7 @@ u64 cfs_avg_vruntime(struct cfs_rq *cfs_rq) { struct sched_entity *curr =3D cfs_rq->curr; s64 avg =3D cfs_rq->avg_vruntime; - long load =3D cfs_rq->avg_load; + long load =3D cfs_rq->sum_weight; =20 if (curr && curr->on_rq) { unsigned long weight =3D scale_load_down(curr->load.weight); @@ -723,7 +723,7 @@ static int vruntime_eligible(struct cfs_rq *cfs_rq, u64= vruntime) { struct sched_entity *curr =3D cfs_rq->curr; s64 avg =3D cfs_rq->avg_vruntime; - long load =3D cfs_rq->avg_load; + long load =3D cfs_rq->sum_weight; =20 if (curr && curr->on_rq) { unsigned long weight =3D scale_load_down(curr->load.weight); @@ -5172,7 +5172,7 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_enti= ty *se, int flags) * * vl_i =3D (W + w_i)*vl'_i / W */ - load =3D cfs_rq->avg_load; + load =3D cfs_rq->sum_weight; if (curr && curr->on_rq) load +=3D scale_load_down(curr->load.weight); =20 diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 47f7b6df634c..54994d93958a 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -679,7 +679,7 @@ struct cfs_rq { unsigned int h_nr_idle; /* SCHED_IDLE */ =20 s64 avg_vruntime; - u64 avg_load; + u64 sum_weight; =20 u64 zero_vruntime; #ifdef CONFIG_SCHED_CORE --=20 2.51.0 From nobody Mon Dec 1 21:31:22 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 8E24E28C00C for ; 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dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="b1DfgIvd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6D1B7C4CEF1; Mon, 1 Dec 2025 06:47:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764571641; bh=9XQI05SugEXGwU+xaX3it0tNYIdIhWS4ca01IHavz9I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=b1DfgIvdGilNmzBhRV73GZAfAQo7+KQOu7HIjG7GVxd6Fqy8RUSBQh9WTW5wVVzgq A1EJ9ZUvOGi5LR+/TVo9Bkc2VeIFH6ZqNzBXcEYH7M/+zXnlznEbI3w4DjKGgQJs/b Y7HuR3sxL6StEArxaIvsYzo965EzeCQEhfR2qMQM0vt+i6IilIanZ8enuiUX47/0eF n89CTlOZ06/ndPZZ47ek3/4DZBtYfbD+mOBc/jF8bsPbvaVUQEhNdG+rsbkXnVYE62 yTuNQijIKQDHsmarMYflsWoWrpsch8K6rvkiPJSP5tMABYFL2+jS9t0uMvV7XBZYGj UYwO4VgD2Bw/w== From: Ingo Molnar To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Juri Lelli , Dietmar Eggemann , Valentin Schneider , Vincent Guittot , Shrikanth Hegde , Linus Torvalds , Mel Gorman , Steven Rostedt , Thomas Gleixner , Ingo Molnar Subject: [PATCH 6/6] sched/fair: Rename cfs_rq::avg_vruntime to ::sum_w_vruntime, and helper functions Date: Mon, 1 Dec 2025 07:46:47 +0100 Message-ID: <20251201064647.1851919-7-mingo@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251201064647.1851919-1-mingo@kernel.org> References: <20251201064647.1851919-1-mingo@kernel.org> 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" The ::avg_vruntime field is a misnomer: it says it's an 'average vruntime', but in reality it's the momentary sum of the weighted vruntimes of all queued tasks, which is at least a division away from being an average. This is clear from comments about the math of fair scheduling: * \Sum (v_i - v0) * w_i :=3D cfs_rq->avg_vruntime This confusion is increased by the cfs_avg_vruntime() function, which does perform the division and returns a true average. The sum of all weighted vruntimes should be named thusly, so rename the field to ::sum_w_vruntime. (As arguably ::sum_weighted_vruntime would be a bit of a mouthful.) Understanding the scheduler is hard enough already, without extra layers of obfuscated naming. ;-) Also rename related helper functions: sum_vruntime_add() =3D> sum_w_vruntime_add() sum_vruntime_sub() =3D> sum_w_vruntime_sub() sum_vruntime_update() =3D> sum_w_vruntime_update() With the notable exception of cfs_avg_vruntime(), which was named accurately. Signed-off-by: Ingo Molnar --- kernel/sched/debug.c | 2 +- kernel/sched/fair.c | 26 +++++++++++++------------- kernel/sched/sched.h | 2 +- 3 files changed, 15 insertions(+), 15 deletions(-) diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index a6ceda12bd35..b6fa5ca6a932 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -828,7 +828,7 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct c= fs_rq *cfs_rq) SPLIT_NS(left_vruntime)); SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "zero_vruntime", SPLIT_NS(zero_vruntime)); - SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "avg_vruntime", + SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "sum_w_vruntime", SPLIT_NS(cfs_avg_vruntime(cfs_rq))); SEQ_printf(m, " .%-30s: %Ld.%06ld\n", "right_vruntime", SPLIT_NS(right_vruntime)); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 2ffd52a2e7a0..41ede30b74cd 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -607,7 +607,7 @@ static inline s64 entity_key(struct cfs_rq *cfs_rq, str= uct sched_entity *se) * Which we track using: * * v0 :=3D cfs_rq->zero_vruntime - * \Sum (v_i - v0) * w_i :=3D cfs_rq->avg_vruntime + * \Sum (v_i - v0) * w_i :=3D cfs_rq->sum_w_vruntime * \Sum w_i :=3D cfs_rq->sum_weight * * Since zero_vruntime closely tracks the per-task service, these @@ -619,32 +619,32 @@ static inline s64 entity_key(struct cfs_rq *cfs_rq, s= truct sched_entity *se) * As measured, the max (key * weight) value was ~44 bits for a kernel bui= ld. */ static void -avg_vruntime_add(struct cfs_rq *cfs_rq, struct sched_entity *se) +sum_w_vruntime_add(struct cfs_rq *cfs_rq, struct sched_entity *se) { unsigned long weight =3D scale_load_down(se->load.weight); s64 key =3D entity_key(cfs_rq, se); =20 - cfs_rq->avg_vruntime +=3D key * weight; + cfs_rq->sum_w_vruntime +=3D key * weight; cfs_rq->sum_weight +=3D weight; } =20 static void -avg_vruntime_sub(struct cfs_rq *cfs_rq, struct sched_entity *se) +sum_w_vruntime_sub(struct cfs_rq *cfs_rq, struct sched_entity *se) { unsigned long weight =3D scale_load_down(se->load.weight); s64 key =3D entity_key(cfs_rq, se); =20 - cfs_rq->avg_vruntime -=3D key * weight; + cfs_rq->sum_w_vruntime -=3D key * weight; cfs_rq->sum_weight -=3D weight; } =20 static inline -void avg_vruntime_update(struct cfs_rq *cfs_rq, s64 delta) +void sum_w_vruntime_update(struct cfs_rq *cfs_rq, s64 delta) { /* - * v' =3D v + d =3D=3D> avg_vruntime' =3D avg_runtime - d*sum_weight + * v' =3D v + d =3D=3D> sum_w_vruntime' =3D sum_runtime - d*sum_weight */ - cfs_rq->avg_vruntime -=3D cfs_rq->sum_weight * delta; + cfs_rq->sum_w_vruntime -=3D cfs_rq->sum_weight * delta; } =20 /* @@ -654,7 +654,7 @@ void avg_vruntime_update(struct cfs_rq *cfs_rq, s64 del= ta) u64 cfs_avg_vruntime(struct cfs_rq *cfs_rq) { struct sched_entity *curr =3D cfs_rq->curr; - s64 avg =3D cfs_rq->avg_vruntime; + s64 avg =3D cfs_rq->sum_w_vruntime; long load =3D cfs_rq->sum_weight; =20 if (curr && curr->on_rq) { @@ -722,7 +722,7 @@ static void update_entity_lag(struct cfs_rq *cfs_rq, st= ruct sched_entity *se) static int vruntime_eligible(struct cfs_rq *cfs_rq, u64 vruntime) { struct sched_entity *curr =3D cfs_rq->curr; - s64 avg =3D cfs_rq->avg_vruntime; + s64 avg =3D cfs_rq->sum_w_vruntime; long load =3D cfs_rq->sum_weight; =20 if (curr && curr->on_rq) { @@ -745,7 +745,7 @@ static void update_zero_vruntime(struct cfs_rq *cfs_rq) u64 vruntime =3D cfs_avg_vruntime(cfs_rq); s64 delta =3D (s64)(vruntime - cfs_rq->zero_vruntime); =20 - avg_vruntime_update(cfs_rq, delta); + sum_w_vruntime_update(cfs_rq, delta); =20 cfs_rq->zero_vruntime =3D vruntime; } @@ -819,7 +819,7 @@ RB_DECLARE_CALLBACKS(static, min_vruntime_cb, struct sc= hed_entity, */ static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *s= e) { - avg_vruntime_add(cfs_rq, se); + sum_w_vruntime_add(cfs_rq, se); update_zero_vruntime(cfs_rq); se->min_vruntime =3D se->vruntime; se->min_slice =3D se->slice; @@ -831,7 +831,7 @@ static void __dequeue_entity(struct cfs_rq *cfs_rq, str= uct sched_entity *se) { rb_erase_augmented_cached(&se->run_node, &cfs_rq->tasks_timeline, &min_vruntime_cb); - avg_vruntime_sub(cfs_rq, se); + sum_w_vruntime_sub(cfs_rq, se); update_zero_vruntime(cfs_rq); } =20 diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 54994d93958a..f0eb58458ff3 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -678,7 +678,7 @@ struct cfs_rq { unsigned int h_nr_runnable; /* SCHED_{NORMAL,BATCH,IDLE} */ unsigned int h_nr_idle; /* SCHED_IDLE */ =20 - s64 avg_vruntime; + s64 sum_w_vruntime; u64 sum_weight; =20 u64 zero_vruntime; --=20 2.51.0