From patchwork Wed Oct 23 15:39:18 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Puranjay Mohan X-Patchwork-Id: 13847301 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 5C3D81CACDE; Wed, 23 Oct 2024 15:39:38 +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=1729697978; cv=none; b=Gc1UgVMJIv+6Ff9CBzdnbKEH/c3FwXHynOKCfmYmRmrEQBBmBBPnFehBUGvV6/pDlVzFMj74hvgysjyzRDWM/rcb46gClsdBeX6xiM0OzvAx7sthQSRTSHRvjEKz0OSd3ptQ+lNhbeEovCEI5m20tP0ooPfcWf48ejqjzguCilA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729697978; c=relaxed/simple; bh=mdNPVEeAmRMvE8WVCh/WUhH2bcKZHSXxSo0wo2DESkA=; h=From:To:Subject:Date:Message-Id:MIME-Version:Content-Type; b=CokR5sMRky7EPrLq+OwQzACOsxvny0DOSBZGrabdsQKjBwmrkxrzgZAcMJrhz/yT5f6a6iAGuVO5tA6Ei3pXjv1WHgYEEYYtxX6mjSsuR3clLwIWJUQQnvR2Jmv9rPpAQalNgjf/a1hbApj9UdsktlO93hWdc/JReKFupZWvsFo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YunnH0yf; 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="YunnH0yf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8D8F4C4CEC6; Wed, 23 Oct 2024 15:39:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1729697977; bh=mdNPVEeAmRMvE8WVCh/WUhH2bcKZHSXxSo0wo2DESkA=; h=From:To:Subject:Date:From; b=YunnH0yffkCAihsC0tg0RcEVUBcTBtsB0ug2bVopVHAnVtK9gbyJtP8z7e9OjzKqv y3elm87l+rQJA5AmW0NpAiZuQcBfRWg8YfQG8CkHR7VTimoB1NdCzibk7s9tEAEksB vRqlbe4Hel0esh5klowxnJUEftF2dv4LHsnoiRawfeCXCIYyL7qYJueUYsfuD+nYlU NqVTt9VyT/Jotqx9W0IbRwE5beA+fkI0JW0txbSFwXwHS0323OL6V23bd9EKtZ0B2l nGWGGddDAMMPyGOauGcRr+b9qvA/2A1Y1hNAEzC9lRI3rKvh3nDlkLF2DTxFBjyRiI lLNtQiXQwXh2Q== From: Puranjay Mohan To: Albert Ou , Alexei Starovoitov , Andrew Morton , Andrii Nakryiko , bpf@vger.kernel.org, Daniel Borkmann , "David S. Miller" , Eduard Zingerman , Eric Dumazet , Hao Luo , Helge Deller , Jakub Kicinski , "James E.J. Bottomley" , Jiri Olsa , John Fastabend , KP Singh , linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org, linux-riscv@lists.infradead.org, Martin KaFai Lau , Mykola Lysenko , netdev@vger.kernel.org, Palmer Dabbelt , Paolo Abeni , Paul Walmsley , Puranjay Mohan , Puranjay Mohan , Shuah Khan , Song Liu , Stanislav Fomichev , Yonghong Song Subject: [PATCH bpf-next v2 0/4] Optimize bpf_csum_diff() and homogenize for all archs Date: Wed, 23 Oct 2024 15:39:18 +0000 Message-Id: <20241023153922.86909-1-puranjay@kernel.org> X-Mailer: git-send-email 2.40.1 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net Changes in v2: v1: https://lore.kernel.org/all/20241021122112.101513-1-puranjay@kernel.org/ - Remove the patch that adds the benchmark as it is not useful enough to be added to the tree. - Fixed a sparse warning in patch 1. - Add reviewed-by and acked-by tags. NOTE: There are some sparse warning in net/core/filter.c but those are not worth fixing because bpf helpers take and return u64 values and using them in csum related functions that take and return __sum16 / __wsum would need a lot of casts everywhere. The bpf_csum_diff() helper currently returns different values on different architectures because it calls csum_partial() that is either implemented by the architecture like x86_64, arm, etc or uses the generic implementation in lib/checksum.c like arm64, riscv, etc. The implementation in lib/checksum.c returns the folded result that is 16-bit long, but the architecture specific implementation can return an unfolded value that is larger than 16-bits. The helper uses a per-cpu scratchpad buffer for copying the data and then computing the csum on this buffer. This can be optimised by utilising some mathematical properties of csum. The patch 1 in this series does preparatory work for homogenizing the helper. patch 2 does the changes to the helper itself. The performance gain can be seen in the tables below that are generated using the benchmark built in patch 4 of v1 of this series: x86-64: +-------------+------------------+------------------+-------------+ | Buffer Size | Before | After | Improvement | +-------------+------------------+------------------+-------------+ | 4 | 2.296 ± 0.066M/s | 3.415 ± 0.001M/s | 48.73 % | | 8 | 2.320 ± 0.003M/s | 3.409 ± 0.003M/s | 46.93 % | | 16 | 2.315 ± 0.001M/s | 3.414 ± 0.003M/s | 47.47 % | | 20 | 2.318 ± 0.001M/s | 3.416 ± 0.001M/s | 47.36 % | | 32 | 2.308 ± 0.003M/s | 3.413 ± 0.003M/s | 47.87 % | | 40 | 2.300 ± 0.029M/s | 3.413 ± 0.003M/s | 48.39 % | | 64 | 2.286 ± 0.001M/s | 3.410 ± 0.001M/s | 49.16 % | | 128 | 2.250 ± 0.001M/s | 3.404 ± 0.001M/s | 51.28 % | | 256 | 2.173 ± 0.001M/s | 3.383 ± 0.001M/s | 55.68 % | | 512 | 2.023 ± 0.055M/s | 3.340 ± 0.001M/s | 65.10 % | +-------------+------------------+------------------+-------------+ ARM64: +-------------+------------------+------------------+-------------+ | Buffer Size | Before | After | Improvement | +-------------+------------------+------------------+-------------+ | 4 | 1.397 ± 0.005M/s | 1.493 ± 0.005M/s | 6.87 % | | 8 | 1.402 ± 0.002M/s | 1.489 ± 0.002M/s | 6.20 % | | 16 | 1.391 ± 0.001M/s | 1.481 ± 0.001M/s | 6.47 % | | 20 | 1.379 ± 0.001M/s | 1.477 ± 0.001M/s | 7.10 % | | 32 | 1.358 ± 0.001M/s | 1.469 ± 0.002M/s | 8.17 % | | 40 | 1.339 ± 0.001M/s | 1.462 ± 0.002M/s | 9.18 % | | 64 | 1.302 ± 0.002M/s | 1.449 ± 0.003M/s | 11.29 % | | 128 | 1.214 ± 0.001M/s | 1.443 ± 0.003M/s | 18.86 % | | 256 | 1.080 ± 0.001M/s | 1.423 ± 0.001M/s | 31.75 % | | 512 | 0.887 ± 0.001M/s | 1.411 ± 0.002M/s | 59.07 % | +-------------+------------------+------------------+-------------+ Patch 3 reverts a hack that was done to make the selftest pass on all architectures. Patch 4 adds a selftest for this helper to verify the results produced by this helper in multiple modes and edge cases. Puranjay Mohan (4): net: checksum: move from32to16() to generic header bpf: bpf_csum_diff: optimize and homogenize for all archs selftests/bpf: don't mask result of bpf_csum_diff() in test_verifier selftests/bpf: Add a selftest for bpf_csum_diff() arch/parisc/lib/checksum.c | 13 +- include/net/checksum.h | 6 + lib/checksum.c | 11 +- net/core/filter.c | 37 +- .../selftests/bpf/prog_tests/test_csum_diff.c | 408 ++++++++++++++++++ .../selftests/bpf/progs/csum_diff_test.c | 42 ++ .../bpf/progs/verifier_array_access.c | 3 +- 7 files changed, 469 insertions(+), 51 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/test_csum_diff.c create mode 100644 tools/testing/selftests/bpf/progs/csum_diff_test.c