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 3645E2F4A14; Sat, 6 Dec 2025 15:59:10 +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=1765036751; cv=none; b=OpOojpDDoohcclZrSmeHB9XsTZuv7teir5l/TIW8ZWJj1hSsarlJakPC8mZlTDXs00hMjmEQmPbzcc5CpbWXR02sjes786NBLVAzZhQXhOeE7TvDhfrMCxIf3jVfuHmvrh7n67t1hMT2x1I9Q41H2mlLWAqp3DrQy/bbEcgn7II= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765036751; c=relaxed/simple; bh=012+E8xXKUl7FevUciQLG/+3QL0/VhlwzljEA6HF1YU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=p96amAMcVENd8Z+WZk5ATmRYHwCSB4E1WLBg2mMMTYyOac4YYY+FHZUy0AGoKzwX5sYmLj16CuY2q3F1Q3rLCGCYuB93+3NoYVJtUqKfV4YkRrkFf60Cx7oLYxzHvKLlADgHTbnrREWsDK5Q4POgW2d4vn1XcEuuj4Vy0jlbooo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WDa3Hv5V; 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="WDa3Hv5V" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 89657C4CEF5; Sat, 6 Dec 2025 15:59:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1765036750; bh=012+E8xXKUl7FevUciQLG/+3QL0/VhlwzljEA6HF1YU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WDa3Hv5Vta3nXLus3rLhEvAo7vXdIAMywXpeT092hrJsNJhDbPYv8Yu/+fBi3it/l kh3SqVs3vPsidvmK13v8yAhaRyZ7LHJ5w/c4TKzSU4edfgmYJ/9L97e+BBbT3j3yt2 29O1waZRjd6yAUifmT0x8SQvAs88vVtXhvbMl7sfWmEJeMq7Z7s5W8U+0ZaIM1c6En vTARuLPi0Cy3ksA4h1ABe8qvGwopu1Rm9vP0aWyzXFhwwYLsVlVvdRqvEFBT5NMjo8 zsXr8cAd/IFfAmNjy7VC25mBSFBhL9pGAEOIBSw7egTWNDiLymL+MY4srtOetqeKxp +aLFDjI1N1C5A== Date: Sat, 6 Dec 2025 05:59:09 -1000 From: Tejun Heo To: Joel Fernandes Cc: John Stultz , LKML , Qais Yousef , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Valentin Schneider , Steven Rostedt , Ben Segall , Zimuzo Ezeozue , Mel Gorman , Will Deacon , Waiman Long , Boqun Feng , "Paul E. McKenney" , Metin Kaya , Xuewen Yan , K Prateek Nayak , Thomas Gleixner , Daniel Lezcano , David Vernet , Andrea Righi , Changwoo Min , sched-ext@lists.linux.dev, kernel-team@android.com Subject: Re: [RFC][PATCH] sched/ext: Split curr|donor references properly Message-ID: References: <20251206001451.1418225-1-jstultz@google.com> <20251206024724.GA71744@joelbox2> 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: Hello, On Sat, Dec 06, 2025 at 09:56:50AM -0500, Joel Fernandes wrote: ... > At a high level, my understanding is BPF schedulers have a lot of say in how to > schedule including precise time slice and preemption control (give or take level > of control and performance reasons). You can in fact have your own 'userland' > queues that the kernel is unaware, IIUC. I am not sure if proxy exec will > transparently work for all those usecases. It will probably work properly only > when BPF scheduling in userland is simple and most of the scheduling is done by > non-BPF kernel code. Maybe this can be resolved by proxy execution explicitly telling sched_ext to essentially dequeue the proxy-executed task so that it's kept more transparent. However, I wonder whether it'd be a useful first step to first deconflict the two config options. ie. Allow sched_ext loading disable proxy execution dynamically so that people don't have to choose between the two config options. I don't know the code intimately, but, from just skimming it, it looks like it can be drained with a static key and some percpu counters. Thanks. -- tejun