From mboxrd@z Thu Jan 1 00:00:00 1970 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 B30732F60C0; Mon, 10 Nov 2025 20:56:38 +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=1762808198; cv=none; b=TBqWDEDC3qKHvMZTd1yiOv3qjo+HcgZ7GK8DkfqzddFV+xyPa5ZHfl7Vi0oztmDLpkNLDdMb0d5iyOLmLZWpD1YffwcuW2NAt0pVP1716Xvs72fVO9A1IhaS2PW9REPdSs5TNUfcSgyTVTj/qyD1vzJphdc6V0CMGuvHK04r6y0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762808198; c=relaxed/simple; bh=H5PKEBoHV3HMMxx7TTlepJ6CAJEwkpwJkeXhwF2qtRk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jAQCdAzlRcoBYgtBBNKzn5Hxrl6Y6HwOELBeDJobmFZ2aIQ+DRWqkoyQ/Iq/A/K5NJeOC1d5l9ejx8xKf2yube0ucKOPpFf117N+cplbYyOfaTz1rS7GTKnsGDkXjmi/n2UrkJ0NBk4X5/HDyRtf9EIm8klUTxFOCTxOo/mA5Js= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tKeG5noB; 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="tKeG5noB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2F89DC116B1; Mon, 10 Nov 2025 20:56:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762808198; bh=H5PKEBoHV3HMMxx7TTlepJ6CAJEwkpwJkeXhwF2qtRk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tKeG5noBM/BRny02DEbXnzQHt1Cd6fGY+pEaOcoZ9JTEQa/8lnNk0UduTrTc9uXiP c65Xk72zSK3li/Cz51amqJyvObyjyc1kj/b+7FICaODesbyg6avKYCDAUaxIqSANG5 JnBtJxMPkjt02geJsYhzYF6XByhKpu8gGrl/0meh9Fretd8l26EpWiRFYGw5rdttVb lWCM4Lk9HxBYo6aqILLXKp55WQ06Qut9ks1wbV9XiPlXXNa70NF58ude9q2UEJ72AK sjcli5YExmV2BEbRN76+nxqtCgJYvbuzd0DqaAekBnNsgZWB1Duapceu90B66yB8a+ idRyy6fU51VBA== From: Tejun Heo To: David Vernet , Andrea Righi , Changwoo Min Cc: Dan Schatzberg , Emil Tsalapatis , sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH v2 01/14] sched_ext: Don't set ddsp_dsq_id during select_cpu in bypass mode Date: Mon, 10 Nov 2025 10:56:23 -1000 Message-ID: <20251110205636.405592-2-tj@kernel.org> X-Mailer: git-send-email 2.51.2 In-Reply-To: <20251110205636.405592-1-tj@kernel.org> References: <20251110205636.405592-1-tj@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: 8bit In the default CPU selection path used during bypass mode, select_task_rq_scx() sets p->scx.ddsp_dsq_id to SCX_DSQ_LOCAL to emulate direct dispatch. However, do_enqueue_task() ignores ddsp_dsq_id in bypass mode and queues to the global DSQ instead, rendering the setting unnecessary. Don't set ddsp_dsq_id from bypass. Just return the selected CPU, which has the effect of waking up the picked idle CPU. Later patches will implement per-CPU bypass DSQs to resolve this issue in a more proper way. v2: Removed incorrect bug fix claim about dangling ddsp_dsq_id triggering WARN_ON_ONCE(). dispatch_enqueue() always clears ddsp_dsq_id even in bypass mode (Andrea). Signed-off-by: Tejun Heo Cc: Andrea Righi --- kernel/sched/ext.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 652a364e9e4c..cf8d86a2585c 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -2521,12 +2521,8 @@ static int select_task_rq_scx(struct task_struct *p, int prev_cpu, int wake_flag s32 cpu; cpu = scx_select_cpu_dfl(p, prev_cpu, wake_flags, NULL, 0); - if (cpu >= 0) { - refill_task_slice_dfl(sch, p); - p->scx.ddsp_dsq_id = SCX_DSQ_LOCAL; - } else { + if (cpu < 0) cpu = prev_cpu; - } p->scx.selected_cpu = cpu; if (rq_bypass) -- 2.51.2