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 1CEE775801; Fri, 24 Apr 2026 01:32:21 +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=1776994342; cv=none; b=bRfsFSvNPZ6k5kLpLEySZc/1ywxq1Q6rMJGisqiaNVPB+tv88H9xoyshayxGUtJiEp0JIR/pGv0kgATEVcbJdTLM5VTgqxqGeCcMX3QsIaO+uWrO3Sh1GQ8tJa/7s4ukHUZ8GZzyeY8mKHSnhIEIcz5egFj8bvjiD+ww/U0S2Nw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776994342; c=relaxed/simple; bh=4qk8mgwdMlpiyWFIxlVE/CktR07iSQhTW0+dQ+sngyk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=YWS6CFoLDdXQGBcb0WWkwWOX2PnTofIxDKJ5df8z6b4om/3NcZzAX2QaEhEjdwQNn/jzrR/fa94V+ajajsioWUSP/J0A+W9nhPv0jY8fkJeOz5xDOVvKvuh7sCBv+dbppU5/OMVsvfTAkehNoOR8nonbAnSyEUGsp4WNF1iR0+g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tX6ogE5c; 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="tX6ogE5c" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8D3DBC2BCAF; Fri, 24 Apr 2026 01:32:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776994341; bh=4qk8mgwdMlpiyWFIxlVE/CktR07iSQhTW0+dQ+sngyk=; h=From:To:Cc:Subject:Date:From; b=tX6ogE5csdiNH+uVUbe29lnhVGx0o5xDwZezRoNlkc/2YZeFAG2ssnW0WGCUaI4eR eoF5Gdees+bcthbtTNNeTw2OA2ySV1hzq+6iig+GmLOcxwVroKOoHS5WEXpr0N9kCy oEzCmfCbBrgp/VZyTYL0UKA/HElbVWDojConi/SN3GMWr+kYnKpE+NEtkrVjNurV64 kvRW7JhbLVSPjVmZssgLxzCzrtaXbAG3DHpd/W1Pmpy6zk2CM6QiOUzid1k771VTUD CocrnIyP6SHFiTBkEAMdZZ8c0OYUrR5MqssHjHmVBkpBx+6bHdaf+FDiNqEMvNm3+1 HGCm1TOtbsfOw== From: Tejun Heo To: David Vernet , Andrea Righi , Changwoo Min Cc: sched-ext@lists.linux.dev, emil@etsalapatis.com, linux-kernel@vger.kernel.org, Cheng-Yang Chou , Zhao Mengmeng , Tejun Heo Subject: [PATCHSET v2 sched_ext/for-7.2] sched_ext: Topological CPU IDs and cid-form struct_ops Date: Thu, 23 Apr 2026 15:32:03 -1000 Message-ID: <20260424013220.2923402-1-tj@kernel.org> X-Mailer: git-send-email 2.53.0 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 of https://lore.kernel.org/r/20260421071945.3110084-1-tj@kernel.org v2: - Add ext-types.h first patch for early subsystem-wide type defs. - cid: publish the cid tables with WRITE_ONCE / read with READ_ONCE; document the visibility contract. - cid-kfuncs: NULL-guard scx_bpf_this_cid / scx_bpf_task_cid for TRACING/SYSCALL callers before any SCX sched has enabled. - cid-struct-ops: use struct_size() for the set_cmask_scratch percpu alloc; cluster __scx_is_cid_type disable with __scx_enabled disable in scx_root_disable(). - cid-kfunc-filter: sync per-entry kfunc flags with each kfunc's primary BTF_ID_FLAGS() declaration (Zhao). pahole intersects flags across occurrences; omitting them drops the flags globally - the visible symptom was KF_IMPLICIT_ARGS getting cleared on scx_bpf_kick_cpu, leaking bpf_prog_aux into vmlinux.h. - cmask: narrow to the helpers this series actually uses; cmask_copy_from_kernel contract and runtime guard. This patchset introduces topological CPU IDs (cids) - dense, topology-ordered cpu identifiers - and an alternative cid-form struct_ops type that lets BPF schedulers operate in cid space directly. Key pieces: - cid space: scx_cid_init() walks nodes * LLCs * cores * threads and packs a dense cid mapping. The mapping can be overridden via scx_bpf_cid_override(). See "Topological CPU IDs" in ext_cid.h for the model. - cmask: a base-windowed bitmap over cid space. Kernel and BPF helpers with identical semantics. Used by scx_qmap for per-task affinity and idle-cid tracking; meant to be the substrate for sub-sched cid allocation. - bpf_sched_ext_ops_cid: a parallel struct_ops type whose callbacks take cids/cmasks instead of cpus/cpumasks. Kernel translates at the boundary via scx_cpu_arg() / scx_cpu_ret(); the two struct types share offsets up through @priv (verified by BUILD_BUG_ON) so the union view in scx_sched works without function-pointer casts. Sub-sched support is tied to cid-form: validate_ops() rejects cpu-form sub-scheds and cpu-form roots that expose sub_attach / sub_detach. - cid-form kfuncs: scx_bpf_kick_cid, scx_bpf_cidperf_{cap,cur,set}, scx_bpf_cid_curr, scx_bpf_task_cid, scx_bpf_this_cid, scx_bpf_nr_{cids,online_cids}, scx_bpf_cid_to_cpu, scx_bpf_cpu_to_cid. A cid-form program may not call cpu-only kfuncs (enforced at verifier load via scx_kfunc_context_filter); the reverse is intentionally permissive to ease migration. - scx_qmap port: scx_qmap is converted to cid-form. It uses the cmask-based idle picker, per-task cid-space cpus_allowed, and cid-form kfuncs throughout. Sub-sched dispatching via scx_bpf_sub_dispatch() continues to work. v2 re-tested on the 16-cpu QEMU: cid-form scx_qmap, cpu-form scx_simple, cid<->cpu cycling, scx_qmap under stress-ng, hotplug auto-restart, and sub-sched (root scx_qmap + cgroup-scoped scx_qmap child). Clean. Based on sched_ext/for-7.2 (c2929bc21dce). 0001-sched_ext-Add-ext_types.h-for-early-subsystem-wide-d.patch 0002-sched_ext-Rename-ops_cpu_valid-to-scx_cpu_valid-and-.patch 0003-sched_ext-Move-scx_exit-scx_error-and-friends-to-ext.patch 0004-sched_ext-Shift-scx_kick_cpu-validity-check-to-scx_b.patch 0005-sched_ext-Relocate-cpu_acquire-cpu_release-to-end-of.patch 0006-sched_ext-Make-scx_enable-take-scx_enable_cmd.patch 0007-sched_ext-Add-topological-CPU-IDs-cids.patch 0008-sched_ext-Add-scx_bpf_cid_override-kfunc.patch 0009-tools-sched_ext-Add-struct_size-helpers-to-common.bp.patch 0010-sched_ext-Add-cmask-a-base-windowed-bitmap-over-cid-.patch 0011-sched_ext-Add-cid-form-kfunc-wrappers-alongside-cpu-.patch 0012-sched_ext-Add-bpf_sched_ext_ops_cid-struct_ops-type.patch 0013-sched_ext-Forbid-cpu-form-kfuncs-from-cid-form-sched.patch 0014-tools-sched_ext-scx_qmap-Restart-on-hotplug-instead-.patch 0015-tools-sched_ext-scx_qmap-Add-cmask-based-idle-tracki.patch 0016-tools-sched_ext-scx_qmap-Port-to-cid-form-struct_ops.patch 0017-sched_ext-Require-cid-form-struct_ops-for-sub-sched-.patch Git tree: git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git scx-cid-v2 kernel/sched/build_policy.c | 2 + kernel/sched/ext.c | 650 +++++++++++++++++++++++++---- kernel/sched/ext_cid.c | 417 ++++++++++++++++++++ kernel/sched/ext_cid.h | 164 ++++++++ kernel/sched/ext_idle.c | 8 +- kernel/sched/ext_internal.h | 203 +++++++--- kernel/sched/ext_types.h | 104 +++++ tools/sched_ext/include/scx/cid.bpf.h | 597 ++++++++++++++++++++++++++++ tools/sched_ext/include/scx/common.bpf.h | 23 ++ tools/sched_ext/include/scx/compat.bpf.h | 24 ++ tools/sched_ext/scx_qmap.bpf.c | 306 ++++++++------- tools/sched_ext/scx_qmap.c | 25 +- tools/sched_ext/scx_qmap.h | 2 +- 13 files changed, 2240 insertions(+), 285 deletions(-) -- tejun