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 817883E0C7B; Thu, 9 Jul 2026 22:28:43 +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=1783636124; cv=none; b=jnXZuPUXY8vgOyuket3MVTGUQx0JsauPpUb9o6SJt102BDFlnfxJT0YFno3sg+uktI1FN7syA5dwEanqjHIjwMaoEXkGdivH7NaDXMZFDONringuA/LA6tYOVDt8nHCyLh1r2UpwH7v6/cKG7jSBgjo56iRfbUwQPei1kIHwSCA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783636124; c=relaxed/simple; bh=D96dwjje24jr8w7xSkguDOOxJ2ndpqnnXTKp4ysyLKw=; h=Date:Message-ID:From:To:Cc:In-Reply-To:References:Subject; b=VG6GwPeavtZqv1U+7OSFvFlWGjBO0wtZsh69NiiIYlQopYGgKn/nwSklqVqGsLTwu1v2kxWB4/T6Pw3c7hXW+FYe6GG7GTw+3+ksMfNKlHvHA3wFMt5XL9PMY+jD5xxR5nTOSB6O6WAFvlYnxMzYPjj7aArP1dN1cL+y4mM8ZF0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nfcoQIi6; 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="nfcoQIi6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 39F811F00A3A; Thu, 9 Jul 2026 22:28:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783636123; bh=hdH1DcnXXrMmmTL/EcrfSwGy9VCl/GOxpCv5y0lWBoI=; h=Date:From:To:Cc:In-Reply-To:References:Subject; b=nfcoQIi6Rbnzk9YoOgqHwYXmn2NBWatrw+Bt/MVI7ACjZ1FHVJ9y67kX2+HIYh4S1 uLTNYbe8qyOHrIsJEMmbRve64sWR43enfIR+9onAqxH1Mm8AfbwrIOI92NmTJ1ysB4 0SfL1gsH70hf93S3Cw0D8D3JQ9P0jk6L22as1VR6oTM7xPXlPzI0hhQkaOPiwHtVIj prq9Ll5r4OhaHM9j2Ykq2tg+hS2nSS8mM0UgsgzWdQr6MsKN9W7HAv6bjot/EUyuaC Nce513Q3pwNTsPjJy4hckI1+fgT0CK8dXS6Z+VCCqIYFVyLTsIsz68NFlwUMfLHgDr OLopUjNL/+Vvg== Date: Thu, 09 Jul 2026 12:28:42 -1000 Message-ID: From: Tejun Heo To: sashiko-bot@kernel.org Cc: David Vernet , Andrea Righi , Changwoo Min , sched-ext@lists.linux.dev, Emil Tsalapatis , linux-kernel@vger.kernel.org In-Reply-To: <20260708215657.DDB5E1F000E9@smtp.kernel.org> References: <20260708212429.3405787-1-tj@kernel.org> <20260708212429.3405787-28-tj@kernel.org> <20260708215657.DDB5E1F000E9@smtp.kernel.org> Subject: Re: [PATCH v4 sched_ext/for-7.3 27/40] sched_ext: Add the SCX_CAP_ENQ_IMMED cap Precedence: bulk X-Mailing-List: sched-ext@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: On Wed, 08 Jul 2026 21:56:57 +0000, sashiko-bot@kernel.org wrote: > - [High] Tasks in a bypassing descendant's runqueue can be permanently > stranded if their nearest non-bypassing ancestor lacks SCX_CAP_BASE on > the CPU. Real limitation and already on the known-limitations list in the cover letter - there's no fallback yet for tasks a sub-scheduler can't run anywhere. The plan is a root-reserved fallback slice in a follow-up series. Not new to this patch. > - [High] scx_caps_for_enq() unconditionally maps all local DSQ enqueues > to SCX_CAP_ENQ_IMMED, allowing sub-schedulers to bypass isolation > guarantees and swamp the CPU with non-IMMED tasks. Same as the v3 round - at this patch ENQ_IMMED is the sole baseline cap; the ENQ vs ENQ_IMMED split that gates non-IMMED work lands later in the series: https://lore.kernel.org/r/70c37a43b2eb1e3d54238c02851f0b62@kernel.org Thanks. -- tejun