From nobody Fri Jun 19 15:47:29 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 0CF07C433EF for ; Fri, 1 Apr 2022 09:13:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344398AbiDAJPl (ORCPT ); Fri, 1 Apr 2022 05:15:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48524 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243987AbiDAJPk (ORCPT ); Fri, 1 Apr 2022 05:15:40 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8EF732662CB for ; Fri, 1 Apr 2022 02:13:47 -0700 (PDT) Received: from dggpemm500023.china.huawei.com (unknown [172.30.72.54]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4KVDrg4p0XzBrrp; Fri, 1 Apr 2022 17:09:39 +0800 (CST) Received: from dggpemm500014.china.huawei.com (7.185.36.153) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Fri, 1 Apr 2022 17:13:44 +0800 Received: from huawei.com (7.220.126.23) by dggpemm500014.china.huawei.com (7.185.36.153) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Fri, 1 Apr 2022 17:13:44 +0800 From: zhangsong To: , , , CC: , , , , , , zhangsong Subject: [PATCH] sched/fair: Allow non-idle task to preempt idle task directly Date: Fri, 1 Apr 2022 17:11:27 +0800 Message-ID: <20220401091127.3234638-1-zhangsong34@huawei.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [7.220.126.23] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpemm500014.china.huawei.com (7.185.36.153) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: zhangsong In check_preempt_tick(), the sched idle task may exectue at least `sysctl_sched_min_granularity` time but any other cfs tasks cannot preempt it. So it is nessesary to ignore the `sysctl_sched_min_granularity` resctriction for sched idle task preemption. Signed-off-by: zhangsong --- kernel/sched/fair.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index d4bd299d6..edcb33440 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4477,6 +4477,15 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sch= ed_entity *curr) struct sched_entity *se; s64 delta; =20 + se =3D __pick_first_entity(cfs_rq); + + if ((cfs_rq->last && se_is_idle(cfs_rq->last) - se_is_idle(curr) < 0) || + (cfs_rq->next && se_is_idle(cfs_rq->last) - se_is_idle(curr) < 0) || + se_is_idle(se) - se_is_idle(curr) < 0) { + resched_curr(rq_of(cfs_rq)); + return; + } + ideal_runtime =3D sched_slice(cfs_rq, curr); delta_exec =3D curr->sum_exec_runtime - curr->prev_sum_exec_runtime; if (delta_exec > ideal_runtime) { @@ -4497,7 +4506,6 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sche= d_entity *curr) if (delta_exec < sysctl_sched_min_granularity) return; =20 - se =3D __pick_first_entity(cfs_rq); delta =3D curr->vruntime - se->vruntime; =20 if (delta < 0) --=20 2.27.0