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 7B148223324; Mon, 27 Oct 2025 18:17:40 +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=1761589060; cv=none; b=E4kPtZLFbkLYOuNmkJIG2Mo2Tz6/FXfX9D/pEuP+M7n6lxFVRbb+acibVJAqAj9uZoEOp8kcT67KqJnxTR9o77S+c4YkLU2+xPTsXvBu4D52r8gdBSe0nGQuaE4nCDnZFN+1Zuk9lVRILST2LDarTEuo8UTMaVYN9N2htcMxvbY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761589060; c=relaxed/simple; bh=JTg6Sb8dfE8YMHOCVIlr8GAXI6KppzQELslM5lFKPf8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Ri0TFENXJzDqLF8XVszt6T7K1ArnvuEhYOTM3qnA1rk085ydnEJzUFQuGzv12ekyMqwQemPR6eW8rkuqWi6oZwKPDpdlhnFgiZNn+C4lOEIfhoUh7SFKe3uNgZ1refQi48MG5kFRNtBugdiJaddnS8BKOhRlyamK6g0SEv0ZPb8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=e8h4S+Vj; 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="e8h4S+Vj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C7982C4CEF1; Mon, 27 Oct 2025 18:17:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761589059; bh=JTg6Sb8dfE8YMHOCVIlr8GAXI6KppzQELslM5lFKPf8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=e8h4S+VjdSrQA9QsZrw2ag48tBRQ0ntfOeRcnDW9VJzBGRkisR7iqIx6hMqXz/Xw4 fvr8mRHn2cFIyuPm5HZhGIi6IIa2fmu1zq9vcPJt9anVP679obZ0nSoHfG3aD0edJM 6rGFl+ije91u25anqS2CRf2pLpxeKfNU/YoYYWPZcNlMucgNks7gBgOxokvIwul2hz y3Q88zjuX9EZr+yS+R53/xC9DpVPUKmQqFsJIau5vo7da6u8j9QsxJTwAeMJ26/5Tx iOpY1hqZ/NwNWuUO/64ajmKeBzYvJIJtQkx9XUT/cwlV3oTAmsu8PlEjtdd7rsOm7p itmbHuXtahrtg== Date: Mon, 27 Oct 2025 08:17:38 -1000 From: Tejun Heo To: Peter Zijlstra Cc: David Vernet , Andrea Righi , Changwoo Min , linux-kernel@vger.kernel.org, sched-ext@lists.linux.dev, Wen-Fang Liu Subject: Re: [PATCH 3/3] sched_ext: Allow scx_bpf_reenqueue_local() to be called from anywhere Message-ID: References: <20251025001849.1915635-1-tj@kernel.org> <20251025001849.1915635-4-tj@kernel.org> <20251027091822.GH3245006@noisy.programming.kicks-ass.net> <20251027181028.GB988547@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251027181028.GB988547@noisy.programming.kicks-ass.net> Hello, On Mon, Oct 27, 2025 at 07:10:28PM +0100, Peter Zijlstra wrote: ... > Just for my elucidation and such.. This is when ttwu() happens and the > CPU is idle and you dispatch directly to it, expecting it to then go run > that task. After which another wakeup/balance movement happens which > places/moves a task from a higher priority class to that CPU, such that > your initial (ext) task doesn't get to run after all. Right? Yes, that's the scenario that I was thinking. Thanks. -- tejun