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 25981332903; Fri, 17 Oct 2025 15:40:14 +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=1760715614; cv=none; b=hoWkIYq6FuK2PAEyFHT3AyoMPkxX/pNS6AX3ubN3jAFOCRvmWHrJQ0+p1N86eGQFfSVq/2iCEaxKTzAiAkFu2FezPWJhsDdtffETkvlREleqMALIZ1sJGtBXkjMpiDa0YZVR0ljFsL3vVEYFlHVNlc8O6Xw9NmcZSTgQrS/Tz3c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760715614; c=relaxed/simple; bh=IQkNW1F4nV6Vxf2WS9P9qIikl4xugxlZvh+MEW6AR3c=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pxOZONIIPwQg39i6i9EgxUTXNAVf8bCHUi6WUjKC0MATqp39aLC9YnibIzWIAgJo30XPPjkJ94z7V1jbvVs3buw0vpgKq5Rs1AiR8N1+v6DTJzSdK6w9FBVjPkwItehbVKNizVC/VH+Lrz371HvdLER8S5oCCWyHzCmoGdhvPsY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MQz1Xnx2; 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="MQz1Xnx2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C725AC4CEE7; Fri, 17 Oct 2025 15:40:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1760715613; bh=IQkNW1F4nV6Vxf2WS9P9qIikl4xugxlZvh+MEW6AR3c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MQz1Xnx2ndMO4J1MPHj1jpyr+DWmWgpPMl9nbXgnvW1QDZk1196EDbInzlMrQiRCq p5HkDiqkDwA2T00U2v6RVqpqELnlWHaafqOQbgcvm87n+pq8UkNMGs/NUwKqCVsIFm PUlu4grZXXs1jegNpRChwRAC6zMHmcFkof4/fD9Hh9oGexChzpO/mAaXf13eqFy56u FjbnHaH7bsIfBBoqHei1+XjmUF0kqINw7sXXRLALomHRWFc5Fgwm8Cnt3HVfhFiget 079tpLQw0PP23ZLv8co1aHKSZi6B6t7m9b6WQuzYKBSXap51HWCLsQfCzwQQ94uJXl 82yVTEAqmmJPQ== Date: Fri, 17 Oct 2025 05:40:12 -1000 From: Tejun Heo To: Andrea Righi Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Joel Fernandes , David Vernet , Changwoo Min , Shuah Khan , sched-ext@lists.linux.dev, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, Luigi De Matteis Subject: Re: [PATCH 06/14] sched_ext: Add a DL server for sched_ext tasks Message-ID: References: <20251017093214.70029-1-arighi@nvidia.com> <20251017093214.70029-7-arighi@nvidia.com> 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: <20251017093214.70029-7-arighi@nvidia.com> On Fri, Oct 17, 2025 at 11:25:53AM +0200, Andrea Righi wrote: > From: Joel Fernandes > > sched_ext currently suffers starvation due to RT. The same workload when > converted to EXT can get zero runtime if RT is 100% running, causing EXT > processes to stall. Fix it by adding a DL server for EXT. > > A kselftest is also provided later to verify: > > ./runner -t rt_stall > ===== START ===== > TEST: rt_stall > DESCRIPTION: Verify that RT tasks cannot stall SCHED_EXT tasks > OUTPUT: > TAP version 13 > 1..1 > ok 1 PASS: CFS task got more than 4.00% of runtime > > [ arighi: drop ->balance() now that pick_task() has an rf argument ] > > Cc: Luigi De Matteis > Co-developed-by: Andrea Righi > Signed-off-by: Andrea Righi > Signed-off-by: Joel Fernandes I don't see anything preventing this to come after patch 11 so that all sched_ext changes are at the end. Am I correct? That'd make applying the patches easier. All the debug and deadline changes can be applied to sched/core and I can pull that and apply sched_ext changes on top. Thanks. -- tejun