From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-177.mta0.migadu.com (out-177.mta0.migadu.com [91.218.175.177]) (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 20828224AF0 for ; Mon, 7 Jul 2025 16:04:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751904263; cv=none; b=EeRaUmzqe/QOopvx+kdTXMQ0lGAp4/pvptrvh/0QcTeor2rhGSDOGHD7+BsLLJeeZvLAfFCivWzPhQcUcEIj1dIQwAxY1jmd7xRb+V+k2Jdm+/ZZgiKHmp6e1M4L4drzs9Iv9QVPcuL6+cwrcksrY5S2cB2cx/DiLPUsF5vbxho= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751904263; c=relaxed/simple; bh=VgGbdWjfNdJsZaWwir4NenUucbIYMBU9rdrFEUgIGKc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ti2mzVyot79HHQaPUVQ/EXn2FrZHONegyU0hOjibDzadhQtN4jvhvienPW6k9cULrRGd/dWsCvkBANJcecf/hYTQTjzUynnIH/GCMAVlqenYFjL4o24dwcP/PeGK6UoDdA2JressYj9Vpxm+qIQNfeWHT554qtPxNOgGLElr9a8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=P4Dl7793; arc=none smtp.client-ip=91.218.175.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="P4Dl7793" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1751904256; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=Ph8TmGaPrzQ55Y1SRwBP8NQBt33l3GOVS2N10HwbBcE=; b=P4Dl7793zDQvgY/HOt1nIlZKta1lzyc2oY49ROzykzygg2YnBR92VPMg+OFEOHKhx9shSg s76cHeNMnpYx0EA+VvYyq4F6gRUmyWkr1xA+6C7k6eerfKdmUIeY9A6Unl/VVoGiShH6UZ uMaYBus+j4hGH7nWRXocgxS/J/hZbZ4= From: Leon Hwang To: bpf@vger.kernel.org Cc: ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, Leon Hwang Subject: [RFC PATCH bpf-next v2 0/3] bpf: Introduce BPF_F_CPU flag for percpu_array map Date: Tue, 8 Jul 2025 00:04:01 +0800 Message-ID: <20250707160404.64933-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT This patch set introduces the BPF_F_CPU flag for percpu_array maps, as discussed in the thread of "[PATCH bpf-next v3 0/4] bpf: Introduce global percpu data"[1]. The goal is to reduce data caching overhead in light skeletons by allowing a single value to be reused across all CPUs. This avoids the M:N problem where M cached values are used to update a map on N CPUs kernel. The BPF_F_CPU flag is accompanied by a cpu field, which specifies the target CPUs for the operation: * For lookup operations: the flag and cpu field enable querying a value on the specified CPU. * For update operations: * If cpu == (u32)~0, the provided value is copied to all CPUs. * Otherwise, the value is copied to the specified CPU only. Currently, this functionality is only supported for percpu_array maps. Links: [1] https://lore.kernel.org/bpf/20250526162146.24429-1-leon.hwang@linux.dev/ Changes: RFC v1 -> RFC v2: * Address comments from Andrii: * Embed cpu to flags on kernel side. * Change BPF_ALL_CPU macro to BPF_ALL_CPUS enum. * Copy/update element within RCU protection. * Update bpf_map_value_size() including BPF_F_CPU case. * Use zero as default value to get cpu option. * Update documents of APIs to be generic. * Add size_t:0 to opts definitions. * Update validate_map_op() including BPF_F_CPU case. * Use LIBBPF_OPTS instead of DECLARE_LIBBPF_OPTS. Leon Hwang (3): bpf: Introduce BPF_F_CPU flag for percpu_array map bpf, libbpf: Support BPF_F_CPU for percpu_array map selftests/bpf: Add case to test BPF_F_CPU include/linux/bpf.h | 3 +- include/uapi/linux/bpf.h | 7 + kernel/bpf/arraymap.c | 56 ++++-- kernel/bpf/syscall.c | 52 ++++-- tools/include/uapi/linux/bpf.h | 7 + tools/lib/bpf/bpf.c | 23 +++ tools/lib/bpf/bpf.h | 36 +++- tools/lib/bpf/libbpf.c | 58 +++++- tools/lib/bpf/libbpf.h | 53 +++++- tools/lib/bpf/libbpf.map | 4 + tools/lib/bpf/libbpf_common.h | 14 ++ .../selftests/bpf/prog_tests/percpu_alloc.c | 170 ++++++++++++++++++ .../selftests/bpf/progs/percpu_array_flag.c | 24 +++ 13 files changed, 460 insertions(+), 47 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/percpu_array_flag.c -- 2.50.0