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 F05BA256C8B; Sat, 1 Aug 2026 08:51:51 +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=1785574313; cv=none; b=O6rxVuo23t/4A0E+bd3dKL6BGI4gifmulPvUsFaaGK97svvJjlAtqXDnPOYxa+5TnSfp80sFqt7VT0hZ78txnNdFeDRDBFgXrQwlA7L2ftErRFMcn/I/rvKEBQ1GBVNBZ23EIgf1d2Cz5I4iHcGCfk6f7G2iuvd4BulXKpghITA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785574313; c=relaxed/simple; bh=z1EYT1mdMHSkFtqJdTIUcbHpk4i/aa/d+JGDmvE1hpk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=P193zQPO39XhxyKVn2jbjS3LlJAmTqC7ISG8L+iRs5jbSfVvabngv9Dn0R2kadibO1qvNncrH6o2vWwxjT7xaRyEvs128HjhbP1zZWAaqY7OJH9N+Vzd3MvMbzW0Lo2S05P9QtDnVJrVOKz3LQL6Cfu16bmmMe0HSrcvbrjZVsY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kVK69Zrm; 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="kVK69Zrm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A559A1F00AC4; Sat, 1 Aug 2026 08:51:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785574311; bh=CiX1sQC9+P5DnbJ2hx3Q+w/JK6q7h4KqOKOaeEP4/5g=; h=From:To:Cc:Subject:Date; b=kVK69ZrmxBR13TP8rV3muerD1iNp2xOkpERoEY/j4w6L37NxLv2WLBA2e0qj1BxmK 8axZi5iXwbllZj+4moDbtAM5OAyhv+mCe2bmXWiQHc86uP3bVXafkkUNWlKVWxMlOy T9F6Ao8qXSRFKg5w2n1YnC3KZV3gWFclW9nyv8pT32149wce10IEjybBT/oHWRofs9 jvdDeckKEAjfvQ0Xp5i7w8gZLv3o6C/8VkKdJbCg7r50JRZ90xybchmfIkvKecjh7n kbpb4ZvfNfrwrG0SWJAwEaBekEVbIMQJjjh6rBuiJ19LPTLkhWGtF+snXerGmFXt13 ujbodDKov+aRw== From: Tejun Heo To: David Vernet , Andrea Righi , Changwoo Min Cc: sched-ext@lists.linux.dev, Emil Tsalapatis , linux-kernel@vger.kernel.org Subject: [PATCHSET sched_ext/for-7.3] sched_ext: Bandwidth-limited rescue execution for stranded tasks Date: Fri, 31 Jul 2026 22:51:38 -1000 Message-ID: <20260801085150.2697653-1-tj@kernel.org> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hello, A sub-scheduler holds only the cids its parent granted and nothing guarantees that they cover its tasks' affinities. A task that can run on none of them currently has no good ending: the scheduler's insert is cap-rejected and reenqueued until the repeat limit ejects the scheduler, or the task stalls into the watchdog. This series adds kernel-side rescue execution. A scheduler marks an insert that may be cap-rejected with SCX_ENQ_RESCUE and the kernel, instead of bouncing it, runs the task on the target cpu at a small configured bandwidth. A rescue starts out non-disruptive. Schedulers that hold caps on the cid largely stay in control of the cpu - a preemption cap, for example, still lets its holder preempt the rescuee. When a rescue goes unserved for too long, it escalates into protected execution. When a cpu's rescue queue stays oversaturated past the overload threshold, the kernel ejects the sub-scheduler with the highest recent rescue consumption on that cpu instead of misblaming the waiter's owner. - 0001-0005 are preps: naming, helper visibility, dsq-move flag vetting and the IGNORE_CAPS preemption waiver. - 0006-0007 synchronize slice/dsq_vtime writes at insertion commit and add SCX_TASK_PROTECTED, the groundwork that lets a kernel-granted slice survive scheduler writes. - 0008-0009 add the rescue machinery and the overload ejection. - 0010 syncs the tools autogen enum headers. - 0011-0012 fix scx_qmap's pinned-task direct dispatch and add rescue support as the demonstration consumer. 0001-sched_ext-Rename-scx_local_or_reject_dsq-to-scx_reso.patch 0002-sched_ext-Make-several-ext.c-helpers-available-outsi.patch 0003-sched_ext-Factor-out-__scx_bpf_now.patch 0004-sched_ext-Reject-internal-enq_flags-in-the-dsq-move-.patch 0005-sched_ext-Make-SCX_ENQ_IGNORE_CAPS-waive-the-preempt.patch 0006-sched_ext-Synchronize-slice-and-dsq_vtime-writes.patch 0007-sched_ext-Add-SCX_TASK_PROTECTED.patch 0008-sched_ext-Add-bandwidth-limited-rescue-execution-for.patch 0009-sched_ext-Eject-the-top-rescue-consumer-on-overload.patch 0010-sched_ext-Sync-tools-autogen-enum-headers.patch 0011-sched_ext-scx_qmap-Idle-check-pinned-tasks-before-di.patch 0012-sched_ext-scx_qmap-Add-rescue-support.patch Based on sched_ext/for-7.3 (ee7aece60817). Git tree: git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git scx-rescue-v1 include/linux/sched/ext.h | 7 + kernel/sched/ext/ext.c | 690 ++++++++++++++++-------- kernel/sched/ext/internal.h | 78 ++- kernel/sched/ext/sub.c | 496 ++++++++++++++++- kernel/sched/ext/sub.h | 41 +- kernel/sched/ext/types.h | 12 + kernel/sched/sched.h | 13 + tools/sched_ext/include/scx/enum_defs.autogen.h | 16 + tools/sched_ext/include/scx/enums.autogen.bpf.h | 3 + tools/sched_ext/include/scx/enums.autogen.h | 1 + tools/sched_ext/scx_qmap.bpf.c | 88 +-- tools/sched_ext/scx_qmap.c | 23 +- tools/sched_ext/scx_qmap.h | 1 + 13 files changed, 1186 insertions(+), 283 deletions(-) -- tejun