From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 DD0284AA035; Thu, 24 Sep 2026 16:57:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790269079; cv=none; b=uNmdqzwzf4To++rR1uvmycNXZmVlf2xIak+ievDT4/3Fq/YFEgB/fQMol6eRubEQZCESCkIaOuCcrhb83AxTv8l7/RzA6FP+nL0r2CgKPkYVHV13QmJJPer/7HRpsB6CMYSvNxsMk3+daPWzq4hsfSu8ZyOPVgiV2D2UJgg/FrY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790269079; c=relaxed/simple; bh=1kaLkFxrgcauaJ9CU9EUWzsWBhexjjiTY5Agq+l/Jng=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References; b=cQwtg3r2/py1NPPTeCt0x5ZghTLbLBmI2+sowDf4x6bomyvM4y7b+njCgbt3Pper1ouS4Mx9MuVSulLZvhcGNyZu4Cwb1yWu86iwOjb7j5SknY32NoGUUbqwiy9asf3jrzDSQYwZ+QNhR3JsNx+mZGhWTLpj2dvSf4a+++FQO1Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WEFrT61o; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="WEFrT61o" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 30E9D1F00899; Thu, 24 Sep 2026 16:57:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790269077; bh=1kaLkFxrgcauaJ9CU9EUWzsWBhexjjiTY5Agq+l/Jng=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=WEFrT61ojUTqGGhXUPJcusVLhUxf92U513U6uMx54tpISVIodsKxYflfnTonJ9bcB GtpiHbEbOou7ovC3rqn/qsiJJt4lS5scavQdmxyrPm6M+DiMA1DkfPrX67YG2lCshI UQPQmdvuc4CiFslNVu5eJIQSHqOeFzTlFdAAAFEK0pqu6j2d00RkiisAD8v2oqEurp oU5gzAVhPO3ohicjqw+BOUngKsBX05UlTb5BxQlfbZU1wuFSU1WQ6qDhUbBOEYur2h pP/JnQYCsxHJm/Z96xoQ4dfGG2Rufds1CbWBuDKBsFPq11NB3cACfyTthqFWxP+oqT JuMGYPq0CXDZg== Date: Thu, 24 Sep 2026 06:57:56 -1000 Message-ID: <6ae9d2d1972afdedf0117ec01aba783f@kernel.org> From: Tejun Heo To: Usama Arif Cc: arighi@nvidia.com, bpf@vger.kernel.org, bsegall@google.com, changwoo@igalia.com, dietmar.eggemann@arm.com, etsal@meta.com, juri.lelli@redhat.com, kprateek.nayak@amd.com, linux-kernel@vger.kernel.org, mgorman@suse.de, mingo@redhat.com, peterz@infradead.org, rostedt@goodmis.org, sched-ext@lists.linux.dev, vincent.guittot@linaro.org, void@manifault.com, vschneid@redhat.com, yphbchou0911@gmail.com Subject: Re: [PATCH] sched_ext: Place dsq_vtime next to dsq_priq In-Reply-To: <20260924161446.3039726-1-usama.arif@linux.dev> References: <20260924161446.3039726-1-usama.arif@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Hello, On Thu, Sep 24, 2026 at 09:14:46AM -0700, Usama Arif wrote: > scx_dispatch_enqueue() calls rb_add() for a vtime-ordered DSQ while > holding dsq->lock. At each level of the descent, scx_dsq_priq_less() > loads the visited task's dsq_vtime, and that comparison selects rb_left > or rb_right from the same task's dsq_priq. In the x86-64 benchmark > configuration, these accesses fell on different 64-byte cache lines > before this change, so a cold visited task could require a second cache > line fill on the dependent descent path. Applied to sched_ext/for-7.4. Thanks. -- tejun