From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-171.mta0.migadu.com (out-171.mta0.migadu.com [91.218.175.171]) (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 138932080C4 for ; Thu, 17 Jul 2025 19:38:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752781107; cv=none; b=OLHIo8BrSe7+39hGql4tMjc6yhLY8DhbtKv6LZ1WNHDttMo1vgvRPCZvedumu+hvHre2qQk9MduIPr3xuqHVKEKjG9YPM7vnSW8IAFJ2LlaZysioVY0udqYsMpqhL3qE5gBXw0bFYgBVanB1djL9Ei9BCLYDMlB0Q2bJNpGwseQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752781107; c=relaxed/simple; bh=u31ewS7J3OV8pXU3O32TUapFTPORcIPr/gpxJZfDV2M=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Idp6JM0WZflNJVAd9l1SAfuurUCQj0T22rZg1YEaUGkC0iS4xiDmarCC07w9x2cT3BwJJTdIBnbXcTnmgGW+qj1kH4XOepwld760lI1IMaPLcmGVHsxEPhhp+YvORQxzf95U7uZSXj2L7igH/veaGDrh/TAzd6RkfnOyTP0RyEo= 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=FmzMOaJw; arc=none smtp.client-ip=91.218.175.171 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="FmzMOaJw" 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=1752781100; 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=ZGeN12KXgxb0qnQuDF2Kp1whOX5zF3rEWjQeYajVxqc=; b=FmzMOaJwZg80Zd8EShLx1YUPh7AaQjglvQqq4yoFcoaX7px90rrXbpIqA5flGACjfcOURX mSzOJDAwNmY5Sf0qlsko1Q+GYh3X+JSNVwgR99DfXYTs3Vs4hjhGYT/MZI7ZI459jsz3EW mubyYd7TTPUcuV9DYuVQL+dIhSmKlmU= From: Leon Hwang To: bpf@vger.kernel.org Cc: ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, yonghong.song@linux.dev, song@kernel.org, eddyz87@gmail.com, dxu@dxuuu.xyz, deso@posteo.net, leon.hwang@linux.dev, kernel-patches-bot@fb.com Subject: [PATCH bpf-next 0/3] bpf: Introduce BPF_F_CPU flag for percpu_array map Date: Fri, 18 Jul 2025 03:37:53 +0800 Message-ID: <20250717193756.37153-1-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 v2 -> v1: * Address comments from Andrii: * Use '&=' and '|='. * Replace 'reuse_value' with simpler and less duplication code. * Replace 'ASSERT_FALSE' with two 'ASSERT_OK_PTR's in self test. 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 | 54 ++++-- 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 | 56 +++++- tools/lib/bpf/libbpf.h | 53 +++++- tools/lib/bpf/libbpf.map | 5 + tools/lib/bpf/libbpf_common.h | 14 ++ .../selftests/bpf/prog_tests/percpu_alloc.c | 172 ++++++++++++++++++ .../selftests/bpf/progs/percpu_array_flag.c | 24 +++ 13 files changed, 459 insertions(+), 47 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/percpu_array_flag.c -- 2.50.1