From patchwork Wed Oct 4 16:23:38 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Vernet X-Patchwork-Id: 13408996 X-Patchwork-Delegate: bpf@iogearbox.net Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 AE9E31BDEB for ; Wed, 4 Oct 2023 16:23:46 +0000 (UTC) Received: from mail-pf1-f176.google.com (mail-pf1-f176.google.com [209.85.210.176]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3C7C2D8; Wed, 4 Oct 2023 09:23:45 -0700 (PDT) Received: by mail-pf1-f176.google.com with SMTP id d2e1a72fcca58-6934202b8bdso1882674b3a.1; Wed, 04 Oct 2023 09:23:45 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696436624; x=1697041424; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=2GXRfMSN09aAE7TFNkE+Gfjpxe8UR8P6twMstwRkNR0=; b=IBgibaeb3tySH+tBV4HlRnHdcxIPHAqseONnXtIX5XuN2gbUsPGjS4xfhpNPRxQRQN 4Zsl8MBjYMlfgyLwK7xM65mmnLjlkVKWWVCF0naBySydnxpOMAWS3usarcmQ15q0nD4p nPf0ZP6TI5rqoZNLx7MaD3TYnvj3BVEd4+fdBoNgFgbXsGKFJQOtMSW0SOeV/E9jRZcu NkT/+ibrSegzyeGzxfa/M1RGMPi6mP2yuGHIsIScRAuCIqBGQZHcN0nC/GH2OT5cl85E kqM5iQLV5AwWwn89r4/eNOtZRBxZ+7aDzzLTRs2vqxtDN/avTMAeXiWvNaHf3tK/E69v p7FA== X-Gm-Message-State: AOJu0Yzwqn054wn06ddh57PPuRhvXLrUTmmI6fkGwQKzuy706dwji++S EcWEuybw0auv35F7EgU6OtnIhjIJxes8XF2g X-Google-Smtp-Source: AGHT+IFiG1rwUI5PqUAiSGgJem7r9bmYI2z9UWg0Y2eYGShiO8nFHSLvDdkY/XFSZuHsoDWrULzb8g== X-Received: by 2002:a05:6a00:1687:b0:68a:5395:7aa5 with SMTP id k7-20020a056a00168700b0068a53957aa5mr2985608pfc.17.1696436624179; Wed, 04 Oct 2023 09:23:44 -0700 (PDT) Received: from localhost ([2620:10d:c090:400::4:3ce7]) by smtp.gmail.com with ESMTPSA id r2-20020a62e402000000b0068aca503b9fsm3426462pfh.114.2023.10.04.09.23.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Oct 2023 09:23:43 -0700 (PDT) From: David Vernet To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: [PATCH bpf-next v2 1/2] bpf: Add ability to pin bpf timer to calling CPU Date: Wed, 4 Oct 2023 11:23:38 -0500 Message-ID: <20231004162339.200702-2-void@manifault.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231004162339.200702-1-void@manifault.com> References: <20231004162339.200702-1-void@manifault.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: bpf@iogearbox.net BPF supports creating high resolution timers using bpf_timer_* helper functions. Currently, only the BPF_F_TIMER_ABS flag is supported, which specifies that the timeout should be interpreted as absolute time. It would also be useful to be able to pin that timer to a core. For example, if you wanted to make a subset of cores run without timer interrupts, and only have the timer be invoked on a single core. This patch adds support for this with a new BPF_F_TIMER_CPU_PIN flag. When specified, the HRTIMER_MODE_PINNED flag is passed to hrtimer_start(). A subsequent patch will update selftests to validate. Acked-by: Song Liu Signed-off-by: David Vernet Acked-by: Hou Tao --- include/uapi/linux/bpf.h | 4 ++++ kernel/bpf/helpers.c | 5 ++++- tools/include/uapi/linux/bpf.h | 4 ++++ 3 files changed, 12 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 70bfa997e896..a7d4a1a69f21 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -5096,6 +5096,8 @@ union bpf_attr { * **BPF_F_TIMER_ABS** * Start the timer in absolute expire value instead of the * default relative one. + * **BPF_F_TIMER_CPU_PIN** + * Timer will be pinned to the CPU of the caller. * * Return * 0 on success. @@ -7309,9 +7311,11 @@ struct bpf_core_relo { * Flags to control bpf_timer_start() behaviour. * - BPF_F_TIMER_ABS: Timeout passed is absolute time, by default it is * relative to current time. + * - BPF_F_TIMER_CPU_PIN: Timer will be pinned to the CPU of the caller. */ enum { BPF_F_TIMER_ABS = (1ULL << 0), + BPF_F_TIMER_CPU_PIN = (1ULL << 1), }; /* BPF numbers iterator state */ diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index dd1c69ee3375..d2840dd5b00d 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -1272,7 +1272,7 @@ BPF_CALL_3(bpf_timer_start, struct bpf_timer_kern *, timer, u64, nsecs, u64, fla if (in_nmi()) return -EOPNOTSUPP; - if (flags > BPF_F_TIMER_ABS) + if (flags & ~(BPF_F_TIMER_ABS | BPF_F_TIMER_CPU_PIN)) return -EINVAL; __bpf_spin_lock_irqsave(&timer->lock); t = timer->timer; @@ -1286,6 +1286,9 @@ BPF_CALL_3(bpf_timer_start, struct bpf_timer_kern *, timer, u64, nsecs, u64, fla else mode = HRTIMER_MODE_REL_SOFT; + if (flags & BPF_F_TIMER_CPU_PIN) + mode |= HRTIMER_MODE_PINNED; + hrtimer_start(&t->timer, ns_to_ktime(nsecs), mode); out: __bpf_spin_unlock_irqrestore(&timer->lock); diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 70bfa997e896..a7d4a1a69f21 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -5096,6 +5096,8 @@ union bpf_attr { * **BPF_F_TIMER_ABS** * Start the timer in absolute expire value instead of the * default relative one. + * **BPF_F_TIMER_CPU_PIN** + * Timer will be pinned to the CPU of the caller. * * Return * 0 on success. @@ -7309,9 +7311,11 @@ struct bpf_core_relo { * Flags to control bpf_timer_start() behaviour. * - BPF_F_TIMER_ABS: Timeout passed is absolute time, by default it is * relative to current time. + * - BPF_F_TIMER_CPU_PIN: Timer will be pinned to the CPU of the caller. */ enum { BPF_F_TIMER_ABS = (1ULL << 0), + BPF_F_TIMER_CPU_PIN = (1ULL << 1), }; /* BPF numbers iterator state */