From patchwork Tue Sep 28 09:30:59 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lorenz Bauer X-Patchwork-Id: 12522237 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E014C433F5 for ; Tue, 28 Sep 2021 09:31:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 50B2B61159 for ; Tue, 28 Sep 2021 09:31:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240092AbhI1JdB (ORCPT ); Tue, 28 Sep 2021 05:33:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37870 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240049AbhI1Jcy (ORCPT ); Tue, 28 Sep 2021 05:32:54 -0400 Received: from mail-wr1-x435.google.com (mail-wr1-x435.google.com [IPv6:2a00:1450:4864:20::435]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5ED99C061775 for ; Tue, 28 Sep 2021 02:31:15 -0700 (PDT) Received: by mail-wr1-x435.google.com with SMTP id i23so56930620wrb.2 for ; Tue, 28 Sep 2021 02:31:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=qOQcHnRA4OzmDMrO4dM1TAmtC+v9d8Z05czXaJ/Qyps=; b=j5i1ZfzTSkWC0KpfTPAm/d98mJ95ltf3LgMoqfjaiA9utXdmH1QA0a8v416ZV5yVsj jmrW70W41xqy93PI0cMh95LsGCbEf1Ve2mqgcAEnOKlxhSvZv5Tok7fiyIbRjj1G5b/y mR2T6ue+VFHxt9gk5aloFDAeBtrrCwW/KDazY= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=qOQcHnRA4OzmDMrO4dM1TAmtC+v9d8Z05czXaJ/Qyps=; b=i8Rp6b8JTbotnRkqXlVEC6BwgxnpZoo/641V1+E4i0j9R5n/+yPABidjoXHbwS9/nN 2IowlIgMxzYletjOGeIgZQmG5PVT5cE6mAAMR1Pj/+eNGf94pAUklUpdWfhmGHat0hCF PCOfXYGtJF6nE+mPYKCU/AA7zUh1KSu7pB+UOmzwBvLbWcKFpZRgEmsoXGew58/r9wAH 8vTQhsHKSLnFtvY/Nn9KnMtdzSuvPJ0C2qtzo9yeRM0wis0uUex35qamYDo3hfNa9B5a 3djw0UA9qyiFd2217Ykf4t/ZY/a+Rs/KJwrIFmGJNm43e+iWTU/uYBRkpwsPu4S+GPmf ZVMg== X-Gm-Message-State: AOAM5300PUtI+aofAeEv+ONoHKHCO7+P8gJg8xwvLuPjk+po6c7gbK97 M3d1V60XD4Z81OmU4b4f0Hv57Q== X-Google-Smtp-Source: ABdhPJy2hW+MI4TO2xRyKlBg3FCAUNVxkc/LlMhgUA1ST4mFFFWUVCwLNNK41Meu19K4TI9a6Cf0aA== X-Received: by 2002:a5d:4eca:: with SMTP id s10mr5240117wrv.255.1632821473526; Tue, 28 Sep 2021 02:31:13 -0700 (PDT) Received: from antares.. (7.2.8.5.7.4.1.5.9.1.3.d.e.b.3.5.f.f.6.2.a.5.a.7.0.b.8.0.1.0.0.2.ip6.arpa. [2001:8b0:7a5a:26ff:53be:d319:5147:5827]) by smtp.gmail.com with ESMTPSA id h15sm18716206wrc.19.2021.09.28.02.31.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Sep 2021 02:31:13 -0700 (PDT) From: Lorenz Bauer To: bjorn@kernel.org, "David S. Miller" , Jakub Kicinski , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Jesper Dangaard Brouer , John Fastabend Cc: kernel-team@cloudflare.com, Lorenz Bauer , netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH bpf-next] bpf: do not invoke the XDP dispatcher for PROG_RUN with single repeat Date: Tue, 28 Sep 2021 10:30:59 +0100 Message-Id: <20210928093100.27124-1-lmb@cloudflare.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net We have a unit test that invokes an XDP program with 1m different inputs, aka 1m BPF_PROG_RUN syscalls. We run this test concurrently with slight variations in how we generated the input. Since commit f23c4b3924d2 ("bpf: Start using the BPF dispatcher in BPF_TEST_RUN") the unit test has slowed down significantly. Digging deeper reveals that the concurrent tests are serialised in the kernel on the XDP dispatcher. This is a global resource that is protected by a mutex, on which we contend. Fix this by not calling into the XDP dispatcher if we only want to perform a single run of the BPF program. See: https://lore.kernel.org/bpf/CACAyw9_y4QumOW35qpgTbLsJ532uGq-kVW-VESJzGyiZkypnvw@mail.gmail.com/ Signed-off-by: Lorenz Bauer --- net/bpf/test_run.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index fcb2f493f710..6593a71dba5f 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -803,7 +803,8 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr, if (ret) goto free_data; - bpf_prog_change_xdp(NULL, prog); + if (repeat > 1) + bpf_prog_change_xdp(NULL, prog); ret = bpf_test_run(prog, &xdp, repeat, &retval, &duration, true); /* We convert the xdp_buff back to an xdp_md before checking the return * code so the reference count of any held netdevice will be decremented @@ -824,7 +825,8 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr, sizeof(struct xdp_md)); out: - bpf_prog_change_xdp(prog, NULL); + if (repeat > 1) + bpf_prog_change_xdp(prog, NULL); free_data: kfree(data); free_ctx: