From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794755197; b=xb/9IHmbCeAz+oLcAj37NszffJ/1DMzkOH7n9csqBwi1GY585gg7Ww3s3LtGGAabR8TB t7ySIRhGK5HvkXl37f0V77QRzhA3Su+cwVdvsPScoJhAQeQkMRu6Wzf/0EXmDN1UQWPBP FJyaWN1G+2qJw2W0mGPrEoZvg2j64AnpzIgQBRD4gNZ4KNhxvIoNTarmZ2lAMS9y8ezUl J3LMRK0eURQvM1l/T7j1bH+j/gr0QjTwOHMaco2N/+xEtgSo3VHAEXHFhvRrpzS+P3HsO oOj83D4jBRs0etcac1WZOUdyxkDNu0we5VqM7jSpqn0eD3o9o0MNuLBe0oFlwtf51tw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794755197; h=Received:DKIM-Signature:Date:Message-ID:From:To:Cc:Subject: In-Reply-To:References:MIME-Version:Content-Type: Content-Transfer-Encoding; bh=weUeyzsssr8dS91Dxqw4Iq8kFGcygNjrCrPAqehGlCc=; b=lQrc1/+0Rj13H6fZ4lIhqnlylzzKF4VtvM6sYrj4zE2oaXJAwX1Qz4ps+qOxCMeHCbWV Fc1/s4XGtKDMz5JMmKWs6F3twPdEtIL2yiOX0Ud0Kh/Znwtbikoq0cDi3eKEqL/FoR6cX kHW+OzSsXtl4pIFa0WaqlxHdQXeIWXq9WR3MDYm3HijPXWXjEVpLV9vRwuHKb71KqxK6i 9COtcb+8mkNY54rKN/cPxVFm3yYJfzw4UhUdU9EMNKQiiYQLsdDE5367GL+aeuGoU1ZpP LjgU9faf6Pjy2PF4HsiSRYbCELZz/7cuGT/jR9ghoE5Od8MfFGDTb4KHE7lBuj/eS0A== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ORwiHLMY; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 15C22606A32C; Sun, 15 Nov 2026 15:06:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ORwiHLMY Received: by smtp.kernel.org (Postfix) with ESMTPSA id 893241F000C6; Sun, 15 Nov 2026 15:06:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794755196; bh=weUeyzsssr8dS91Dxqw4Iq8kFGcygNjrCrPAqehGlCc=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=ORwiHLMYmxXPyBaOautNu04UKw3d887VJtdDVPax8pPHotHrCmKMkIyvRpu+hEzYy gt9xSGElu9PnvdWQk182cqwkh2M94cHZOAJAu1XhJK10xHtHJvLiNdtp8mL97bUaVp w7L7mx+Y2twfAf4B9+HUNoIoSkKlMy8gpPwzeTtMXF16yWyT41sIinLmdfgbMf3nuR D4aitWGt4WgmiLx5RXKLoZRYDOb+vkVN6DvyrtPPNERciCARX7vvIxtsgBqY2ZHbh+ gENgRrBxtRse7T4gzRJ2PIKd5Qn2saK8eSKgo84axX7OFDOef4xKAYbsr2N7wE2Ayi NZ6uTQz9fbjfg== Date: Sun, 15 Nov 2026 05:06:35 -1000 Message-ID: <598bee2c48b23aee00c404d1183b581a@kernel.org> From: Tejun Heo To: Tao Cui , Peter Zijlstra Cc: void@manifault.com, arighi@nvidia.com, changwoo@igalia.com, mingo@redhat.com, sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Tao Cui Subject: Re: [PATCH 1/2] sched/core: Pass ENQUEUE_RQ_SELECTED on initial enqueue In-Reply-To: <20261112144935.583937-2-cui.tao@linux.dev> References: <20261112144935.583937-1-cui.tao@linux.dev> <20261112144935.583937-2-cui.tao@linux.dev> X-Mailing-List: bpf@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit On Thu, Nov 12, 2026 at 10:49:34PM +0800, Tao Cui wrote: > select_task_rq() sets WF_RQ_SELECTED and ttwu_do_activate() maps it to > ENQUEUE_RQ_SELECTED so enqueue_task_scx() knows whether ops.select_cpu() > ran. wake_up_new_task() also calls select_task_rq() but activates the > new task without the flag, so on the fork path ops.enqueue() never sees > SCX_ENQ_CPU_SELECTED and SCX_EV_SELECT_CPU_FALLBACK never counts a > fork-path fallback: a misbehaving select_cpu() leaves no trace in the > counters, and schedulers testing SCX_ENQ_CPU_SELECTED run a redundant > select_cpu_dfl() on tasks select_cpu() already placed. > > Set ENQUEUE_RQ_SELECTED on the initial enqueue when select_task_rq() was > called, matching the wakeup path. Only sched_ext consumes the flag. > > Fixes: 9b671793c7d9 ("sched_ext, scx_qmap: Add and use SCX_ENQ_CPU_SELECTED") > Signed-off-by: Tao Cui Acked-by: Tejun Heo Peter, how do you want to route this? I can take it through sched_ext too given that the flag is only consumed by sched_ext. Thanks. -- tejun