From patchwork Mon Oct 2 23:47:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Vernet X-Patchwork-Id: 13406621 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 B98661E521 for ; Mon, 2 Oct 2023 23:47:13 +0000 (UTC) Received: from mail-pj1-f42.google.com (mail-pj1-f42.google.com [209.85.216.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6E00FBD; Mon, 2 Oct 2023 16:47:12 -0700 (PDT) Received: by mail-pj1-f42.google.com with SMTP id 98e67ed59e1d1-27740ce6c76so218614a91.0; Mon, 02 Oct 2023 16:47:12 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696290431; x=1696895231; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=DVMLROc3eiE12rYXMNdufnFTC1ndnWQSfH8g24Ty96g=; b=syc24e3HDi4jCjnINXIafc+MiQ+6RKA29oVfw1zXZW3G2wMOkRPYg6gC1hj1v3k9A5 gu8hl85I0/mjG5G3rlnvda4iiVflTRbQfqWcH85Wz3UhipYyqjOEYAqmoq75CBZ6ANhM rEtHQ9vzODiEAENam4WA0sN47xS+j3zyhh5SCeZvq390vW3165NR25jazfbkqoHboS7W FkoB0HqXLO/hJ2Qda35Q9v/xh0qqw57ObAyAyZwFuB/YyLa8vZ0g+yTbSKeWgY1mlaNs mnlye3r37TzLry7JUOV59wNOx/XBTndRjUwdblvtCtGz/hEP7Nw/sh71PHRnTlH84w1s 0bWw== X-Gm-Message-State: AOJu0YzygmUwIhKoH00gCsi7hSb0ncJuTegGWiPFYtriM9Oe+BTnx3mG iRU3cAARQhfFBNmh3C/4hl8p4WYS6XhrKSSG X-Google-Smtp-Source: AGHT+IG1F0c9euUmaxbN5hsL+bTx3fCi+E4+ssLdYnBiRCxG58MXYD4AdJHDudvL7FGsq5lYARff5A== X-Received: by 2002:a17:90a:16c1:b0:274:748c:9c55 with SMTP id y1-20020a17090a16c100b00274748c9c55mr10070476pje.20.1696290431298; Mon, 02 Oct 2023 16:47:11 -0700 (PDT) Received: from localhost ([2620:10d:c090:400::4:d0e0]) by smtp.gmail.com with ESMTPSA id ji17-20020a170903325100b001c444106bcasm28340plb.46.2023.10.02.16.47.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Oct 2023 16:47:10 -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, himadrispandya@gmail.com, julia.lawall@inria.fr Subject: [PATCH bpf-next 1/2] bpf: Add ability to pin bpf timer to calling CPU Date: Mon, 2 Oct 2023 18:47:07 -0500 Message-ID: <20231002234708.331192-1-void@manifault.com> X-Mailer: git-send-email 2.41.0 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-1.4 required=5.0 tests=BAYES_00, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE, SPF_PASS autolearn=no 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. Signed-off-by: David Vernet Acked-by: Song Liu --- 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 */