From nobody Mon Feb 9 12:00:52 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4B941C76195 for ; Tue, 28 Mar 2023 11:08:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232778AbjC1LID (ORCPT ); Tue, 28 Mar 2023 07:08:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39522 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232532AbjC1LHN (ORCPT ); Tue, 28 Mar 2023 07:07:13 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B39D37EEE for ; Tue, 28 Mar 2023 04:07:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=kQG2l/tKeYJT6zXifHihyhG77ZWdoGPsh4TIiXCPCIM=; b=lbu36IMjlnbZ2kmncp4XjiFD4S i3J0R2TMJ6Tb4BEUJrGw6WRS0uq/qns36hVsnHPE8jKj46BT53O/mrq/aoeKyThcg5llGdZQI4bA2 mZLeqDFN8rvhncnZXd8/ViPxsT2441z1IOb5LrTAnMa07YRzKV/88YGt2Rzmp4vVA9lPbx0MxGRzd sEMG5dzn4SsyKVRZdJy2NqPNPUEDzhw4kjKmf3NbpCemlCedJ8wIkMUI+atWrQwjM6PHOFShG7pLn W2/doO/rgzSzrXb27d18r5M8WYR3rS8/02+a+fJjE0l8PSb1CI1M05nbH2McX+pskO+28pVj8Yf/a QZsg6WYw==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1ph79m-008MDF-5D; Tue, 28 Mar 2023 11:06:26 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 6994F303128; Tue, 28 Mar 2023 13:06:23 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 117D32CB8D7A2; Tue, 28 Mar 2023 13:06:21 +0200 (CEST) Message-ID: <20230328110354.712296502@infradead.org> User-Agent: quilt/0.66 Date: Tue, 28 Mar 2023 11:26:38 +0200 From: Peter Zijlstra To: mingo@kernel.org, vincent.guittot@linaro.org Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, corbet@lwn.net, qyousef@layalina.io, chris.hyser@oracle.com, patrick.bellasi@matbug.net, pjt@google.com, pavel@ucw.cz, qperret@google.com, tim.c.chen@linux.intel.com, joshdon@google.com, timj@gnu.org, kprateek.nayak@amd.com, yu.c.chen@intel.com, youssefesmat@chromium.org, joel@joelfernandes.org, efault@gmx.de Subject: [PATCH 16/17] [RFC] sched/eevdf: Minimal vavg option References: <20230328092622.062917921@infradead.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Alternative means of tracking min_vruntime to minimize the deltas going into avg_vruntime -- note that because vavg move backwards this is all sorts of tricky. Also more expensive because of extra divisions... Not found this convincing. Signed-off-by: Peter Zijlstra (Intel) --- kernel/sched/fair.c | 51 ++++++++++++++++++++++++++++---------------= ----- kernel/sched/features.h | 2 + 2 files changed, 32 insertions(+), 21 deletions(-) --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -732,28 +732,37 @@ static u64 __update_min_vruntime(struct =20 static void update_min_vruntime(struct cfs_rq *cfs_rq) { - struct sched_entity *se =3D __pick_first_entity(cfs_rq); - struct sched_entity *curr =3D cfs_rq->curr; - - u64 vruntime =3D cfs_rq->min_vruntime; - - if (curr) { - if (curr->on_rq) - vruntime =3D curr->vruntime; - else - curr =3D NULL; + if (sched_feat(MINIMAL_VA)) { + u64 vruntime =3D avg_vruntime(cfs_rq); + s64 delta =3D (s64)(vruntime - cfs_rq->min_vruntime); + + avg_vruntime_update(cfs_rq, delta); + + u64_u32_store(cfs_rq->min_vruntime, vruntime); + } else { + struct sched_entity *se =3D __pick_first_entity(cfs_rq); + struct sched_entity *curr =3D cfs_rq->curr; + + u64 vruntime =3D cfs_rq->min_vruntime; + + if (curr) { + if (curr->on_rq) + vruntime =3D curr->vruntime; + else + curr =3D NULL; + } + + if (se) { + if (!curr) + vruntime =3D se->vruntime; + else + vruntime =3D min_vruntime(vruntime, se->vruntime); + } + + /* ensure we never gain time by being placed backwards. */ + u64_u32_store(cfs_rq->min_vruntime, + __update_min_vruntime(cfs_rq, vruntime)); } - - if (se) { - if (!curr) - vruntime =3D se->vruntime; - else - vruntime =3D min_vruntime(vruntime, se->vruntime); - } - - /* ensure we never gain time by being placed backwards. */ - u64_u32_store(cfs_rq->min_vruntime, - __update_min_vruntime(cfs_rq, vruntime)); } =20 static inline bool __entity_less(struct rb_node *a, const struct rb_node *= b) --- a/kernel/sched/features.h +++ b/kernel/sched/features.h @@ -9,6 +9,8 @@ SCHED_FEAT(PLACE_FUDGE, true) SCHED_FEAT(PLACE_DEADLINE_INITIAL, true) SCHED_FEAT(PLACE_BONUS, false) =20 +SCHED_FEAT(MINIMAL_VA, false) + /* * Prefer to schedule the task we woke last (assuming it failed * wakeup-preemption), since its likely going to consume data we