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 69C7746982A; Tue, 1 Sep 2026 08:29:17 +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=1788251358; cv=none; b=O/8QTaerOVuX9pXxiBP+swJIZi8t9GROflpQOw85kfoPqOZ4QKkI1Ix+k3pzJ8P86eBod7T/OBO8DcfiSZeAP38J/+EPdkjr3AE+zOIsn9nm+iVi2gzcyDK1bDeWHiAWLLMWmcBDWYROmszAttLOGTkr9wmJk//bZFCTTen7Yf4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788251358; c=relaxed/simple; bh=+wz7X+nGwy6yN49W8530mdNG3yywKtAtrsWlqbFpVRQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JzRyfvM2kv90NOKwaheRVn5fc0BfSiIssUNrsa3M3/BnoC58f+Iy4rQ/LYAei/5njr+ZTdp4HSEknlhpzziI7CYVIWRLyi8sjk2ml+no/ZheQ/fzwWam5JgwQkBppy/m23pqO0T1BoGxZ6iOW7i4xOCWzc6FKvJN341mSzCmCPM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Q+4reqlG; 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="Q+4reqlG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 255901F000E9; Tue, 1 Sep 2026 08:29:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788251357; bh=OQJptYqXaP7yBSHhBlmJaEuEUnH/RFb3w5rg8tQnB/E=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Q+4reqlGibgMNlTMZdMdZYyc5ixOckR5PblEyN8tdoEw08wbK1Di1pkRgjGoT4OFB rOdNeCK/Mce7umrdpRaR6Q4P3O+yDJji7X8kbWA77rrCzIe0+2hS3XdKiPWZMbd+VZ +UOFxnpmOASPdN9xFs8ymMx/CpJY8ABr+65bo+5yeuV2FHFe5DHZP67qsDIbxoAY1c lJTz9+GHzUtuU7MuhlTd/5fTiHIl/aWGmqN00CwdCsSS2p5Klu1Nv2YO5haOTMKA9Z r5755gX/75CNqtoIKJ4LgIBxdxt9H8Qum78aDM/HFvmP78edoRjjzRKJlxxv7CCT/D Al+CjPPcqV4dQ== Date: Mon, 31 Aug 2026 22:29:16 -1000 From: Tejun Heo To: Tao Cui Cc: void@manifault.com, arighi@nvidia.com, changwoo@igalia.com, michalblk@google.com, liwanwu@kylinos.cn, sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Tao Cui Subject: Re: [PATCH 1/2] sched_ext: fix vtime priority queue inversion on wide vtime spread Message-ID: References: <20260901024038.730424-1-cui.tao@linux.dev> <20260901024038.730424-2-cui.tao@linux.dev> Precedence: bulk X-Mailing-List: bpf@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: <20260901024038.730424-2-cui.tao@linux.dev> Hello, On Tue, Sep 01, 2026 at 10:40:37AM +0800, Tao Cui wrote: ... > than 2^63 apart. Unlike CFS, which enforces that invariant with > min_vruntime clamping, sched_ext takes dsq_vtime directly from the BPF > scheduler and cannot bound the spread. A scheduler that inserts tasks This doesn't make any practical sense. dsq_vtime is by (implicit) definition a rolling cursor. Please feel free to add documentation if that'd help. Thanks. -- tejun