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 48BD775801; Sun, 2 Aug 2026 21:54:48 +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=1785707689; cv=none; b=qbroaXMOJjyR63MTwy3mMPO9PITfEuaualCqvl5jzBxqZXiaxULVX09mg1Q2JPqNRanEznhmLowttjo6YQLgvveJM4Z/DdLEaxmCyXGSOANvXj/QcyJjGRqoz3GeCYhggDZ+/Ubd8ODeJ3gNRurEwG8tYh9dj4ljfBChdUsQdnc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785707689; c=relaxed/simple; bh=cxQw2/b/J4xBQO5TVVUUzObXXV89h5BwvBDLj8EAacg=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=DKJUOO8mWoW8Gb+Ce/lUtlPi4le7b2ojO8rr3NWyhhTKOC7rxWHqXmvbgUUlCtl4IkqSt4aSTqXVurtFzYOSGjEeS7G+N4J1nG1s51DIATPWGYdnDu08LKcWQgWTbAeZD7+j43/22dO/nWMP0RoL7gio9cVPRBr2xqjlYyiCKDI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aE/Rl+SK; 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="aE/Rl+SK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D2B421F000E9; Sun, 2 Aug 2026 21:54:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785707688; bh=NVwjZYSYQt34aKOHmt/XjMl9xoBqi7S5UyPbN2YyzZg=; h=From:To:Cc:Subject:Date; b=aE/Rl+SKY3ZOG6YyJYNv/Zj2T5jli2QxS66OnDdN2Vpaz62HTQLfryWcXd+dtWFoS PKu0I2+tEZZfcEQKkb48oWqDHq1Hlvec0eD3WV3USZPIMl67YFuNAXwiBaH1cOtQiW p69U42J4zIXew7y9fPafz5QMkNVHTMcdAx2MbFPCs8lEeYn5FbK167Nc1O8pjfZ3xx z8M3W0gLaqafDnORTHNLanygn+8m2KgTWlaK/HO6rdI2pg95t2KDsyw18ntK0DBlLl 9asPeRLTiNzAG2ft4HAOMVdq6oKp9GfYABEoWavHV1W6VQ8MbntCwmLL0Wpn+whgpC xPPVAvUNIVN1A== 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 v2 sched_ext/for-7.3] sched_ext: Bandwidth-limited rescue execution for stranded tasks Date: Sun, 2 Aug 2026 11:54:35 -1000 Message-ID: <20260802215447.3134509-1-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, v2: Changes from the sashiko AI review: - Declare scx_sched_all outside the CONFIG_EXT_SUB_SCHED block, the definition is unconditional (0002). - Track the overload grace and usage-decay timestamps in jiffies_64 so that 32-bit arithmetic on them can't wrap (0009). - Drop the now-unread always_enq_immed rodata mirror (0011). v1: https://lore.kernel.org/r/20260801085150.2697653-1-tj@kernel.org 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 (c5b9316cf3d5). Git tree: git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git scx-rescue-v2 include/linux/sched/ext.h | 7 + kernel/sched/ext/ext.c | 690 ++++++++++++++++-------- kernel/sched/ext/internal.h | 78 ++- kernel/sched/ext/sub.c | 497 ++++++++++++++++- 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 | 89 +-- tools/sched_ext/scx_qmap.c | 24 +- tools/sched_ext/scx_qmap.h | 1 + 13 files changed, 1187 insertions(+), 285 deletions(-) -- tejun