From nobody Sat Apr 18 04:21:49 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 AEC74C43334 for ; Mon, 18 Jul 2022 09:50:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234264AbiGRJuC (ORCPT ); Mon, 18 Jul 2022 05:50:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40436 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234221AbiGRJuB (ORCPT ); Mon, 18 Jul 2022 05:50:01 -0400 Received: from mail-pl1-x634.google.com (mail-pl1-x634.google.com [IPv6:2607:f8b0:4864:20::634]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CF8462FE for ; Mon, 18 Jul 2022 02:50:00 -0700 (PDT) Received: by mail-pl1-x634.google.com with SMTP id g17so8539057plh.2 for ; Mon, 18 Jul 2022 02:50:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=IskrYUTwZ5u1ebt19AyhEL1vhoFuS3Dpla4INxfY6cs=; b=bFSDWuWZZmzQ2zV37AFBRmxqzduFyTinMbFnWlSaWenaGE0D8fl5aZ+cEWvVTaL/jt s+STrrUcxroQaW4PtgtKgdzBJ4yFOrxYV2OgYPp+xlfh9MfTVdIhecroEIfagALilGIT ou5LZRPc4iVmsHBiimQTs+3Go6IgDjl2RIE2B1sGWKJzjicMVJNFfhObLUuy41FlB+3/ 1JdjAtFCgRtaE3Z/Pidle5j/mYJxsCLXVgOOuteCnkr4GsSkFuuYqlltmr1c0J5wMhM9 5qIp6Bwhx7XFgvv7A/BHtUbpqjhIunqpA2aKf+OTULzBsiA8Fj61a/253sM95QsE8JOf sizw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=IskrYUTwZ5u1ebt19AyhEL1vhoFuS3Dpla4INxfY6cs=; b=m7AMJjIwh4d4brxcsk6xQG0jlm/Qn2twsypJm7xg63ZrmcjpgmrBGs3OraEoCfMe5e pWgHVQofIbB2nasILLDgGhz5KuMCYkBCFHTXhHrnJU/rndw6Zf9MYOjzDNBc4RiyIJLf ppEObNcftkHsP7p5VCEEHHwYqYFPinVe1MBM1sXvP/D2WL+JDZktz8Kgp3O+b3emF4Yz Xakvtsqf/ZC5HzPtLS7A6MklDlEJgmfeM3JkPiOnSC9CfgLNi3PzVZy30aX0kePT2uHn Ylh5W2kovMfH8TXodt0A0vf/JsciJDbW8TvXW8qAdENC7LKDX0ZJwlv31xh66GsF9cNa oMTw== X-Gm-Message-State: AJIora9Px4xkW1zz+OPpU75KOE6U2jLs/GKnwO//8Ec9Yw84m+5870Gs 04WwyyDHlYKPCiS4MI/ABv6aYA== X-Google-Smtp-Source: AGRyM1uhCBFo+SfoWW8MQ4va92GFl07kKEJOEHPfIKPXAsNsPdg3M8sDyGbPv4t1bjXUZo73d0i5HQ== X-Received: by 2002:a17:902:8505:b0:16c:cf05:dc59 with SMTP id bj5-20020a170902850500b0016ccf05dc59mr15012860plb.125.1658137800349; Mon, 18 Jul 2022 02:50:00 -0700 (PDT) Received: from GL4FX4PXWL.bytedance.net ([139.177.225.252]) by smtp.gmail.com with ESMTPSA id t12-20020a170902e84c00b0016a111c83cdsm9072679plg.119.2022.07.18.02.49.56 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 18 Jul 2022 02:49:59 -0700 (PDT) From: Peng Zhang To: mingo@redhat.com, peterz@infradead.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, linux-kernel@vger.kernel.org Cc: "zhangpeng.00" Subject: [PATCH] sched/fair: optimize entity_tick() Date: Mon, 18 Jul 2022 17:49:37 +0800 Message-Id: <20220718094937.37360-1-zhangpeng.00@bytedance.com> X-Mailer: git-send-email 2.32.1 (Apple Git-133) MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: "zhangpeng.00" entity_tick() will be called to check preemption by calculating each sched_entity's time_slice in a task group tree from bottom to top. If a need_resched_flag is set by a checking of a sched_entity, there is no necessary to check preemption of the sched_entity's parent and ancestor entity. So we can test if the need_resched_flag has been set before calling check_preempt_tick() to avoid unnecessary calculations. Signed-off-by: zhangpeng.00 Reported-by: kernel test robot --- kernel/sched/fair.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index a78d2e3b9d49..ee23afe22ac7 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4757,7 +4757,7 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entit= y *curr, int queued) return; #endif =20 - if (cfs_rq->nr_running > 1) + if (cfs_rq->nr_running > 1 && !test_tsk_need_resched(rq_of(cfs_rq)->curr)) check_preempt_tick(cfs_rq, curr); } =20 --=20 2.20.1