From nobody Wed Dec 24 18:19:16 2025 Received: from mail-il1-f173.google.com (mail-il1-f173.google.com [209.85.166.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6B310A3D for ; Thu, 25 Jan 2024 00:30:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.173 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706142626; cv=none; b=GeMWGzMkdkYvnva9lqimrBrjJFgpYZG6+9N7+pjO1jCMbq0y/Vf8mjH0pTQ2PMaf5cFpn1N2bJHp870bAc0kyIT0pB7bjPAbCUtjYd7ffCbN2HUdKn9OpnS4L4Q0TtbovdmC3JlX1Jq4f40GfkpHU8LiP6clhmlKohIQ8kmPl1Y= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706142626; c=relaxed/simple; bh=qkngexUKlfn+hMPunN78J4XlCpnaY0JzFvOY2CvOwFw=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=dNooLMln2mIiQIRwZ2DFzKoRd+EMBrOEkRcBL/FAHJmu8nio+EMrCrj2kfI6p8nJsbtQqt50yb5jsgB6PeAvPwQaxsKC+yTfXxAi6d1opEZNa1lGaRQiV0xea5YeudbPWEm1yr7DtqEkDc7yCySJUoccIJ0RCHPfPuWOM03cfiQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=fastly.com; spf=pass smtp.mailfrom=fastly.com; dkim=pass (1024-bit key) header.d=fastly.com header.i=@fastly.com header.b=RrRYhH/i; arc=none smtp.client-ip=209.85.166.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=fastly.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=fastly.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=fastly.com header.i=@fastly.com header.b="RrRYhH/i" Received: by mail-il1-f173.google.com with SMTP id e9e14a558f8ab-3627e9f1b40so18328715ab.1 for ; Wed, 24 Jan 2024 16:30:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fastly.com; s=google; t=1706142622; x=1706747422; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=VV39OAkRpCVAHLKUI3lU3BvBDLbvOa7qJKwdNWq/qLo=; b=RrRYhH/iEsRHUmKTquV2y95C9aRsKyCGxgflWpj0V8QQpjBruF+BKUVz0LDlNsI313 8aI4+U3ixR45wYg8g3NTlExvkD//EWmymdG7TeA4zAT0wedY0BX8zsZUlPWuKfQoeszg uTrztf7SZyKmfaLyL7opJRTMLitGJKRVxeNEs= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706142622; x=1706747422; 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=VV39OAkRpCVAHLKUI3lU3BvBDLbvOa7qJKwdNWq/qLo=; b=ObL84/esDSLVDZalGJ5g1RIVRBxhZpZpDig+dQqroJnCSawCbsXaeioF6QRhp6/EmF ks4ogfmL1egb+J1GWY7m57OhLdx8sORfPmaIbNtcHVPO0oquz5Dp4npEilan4DlO0lc8 k/fmviaG50igEI0520rvbHODQ6c5QoLDkWT7rLDMi0s+HYjfnR9HHTPAOMyzNQdL+vam iy5cEu/dJMt9gyU7farEcOQL9hZdX6BFubSxw8tzCzqe3qGCqV0sk7Y4SJuEhXtA7kU7 z8UYnRj4InlGzBhKKMbJQe6gx0EX4F7anTRaxMuzZbW4oE5qlqaHo3SDZCmZfnjvgP0+ p0Gg== X-Gm-Message-State: AOJu0YzbuaaH0iOWeBp5ZE2D/bgVQEV2OU0bSmyZv+KOxGDfd5JUh0ft RsC0jOkPtJl1j3qQww8VmXCUecoCfjeE9S85EiBgxVXhOxQZ6Arnsdvrk3QTSUk= X-Google-Smtp-Source: AGHT+IGnYPOifsV33or2bBeZeQG6+k6OkdXKBZqmsoPyQU14DL3OI0VG4LUd5evkY/JboI23hyOIDQ== X-Received: by 2002:a92:cec9:0:b0:361:ac44:150a with SMTP id z9-20020a92cec9000000b00361ac44150amr285943ilq.57.1706142622585; Wed, 24 Jan 2024 16:30:22 -0800 (PST) Received: from localhost.localdomain ([2620:11a:c018:0:ea8:be91:8d1:f59b]) by smtp.gmail.com with ESMTPSA id w10-20020a63d74a000000b005cd945c0399sm12550486pgi.80.2024.01.24.16.30.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jan 2024 16:30:21 -0800 (PST) From: Joe Damato To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: chuck.lever@oracle.com, jlayton@kernel.org, linux-api@vger.kernel.org, brauner@kernel.org, edumazet@google.com, davem@davemloft.net, alexander.duyck@gmail.com, sridhar.samudrala@intel.com, kuba@kernel.org, weiwan@google.com, Joe Damato Subject: [net-next v2 1/4] eventpoll: support busy poll per epoll instance Date: Thu, 25 Jan 2024 00:30:11 +0000 Message-Id: <20240125003014.43103-2-jdamato@fastly.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240125003014.43103-1-jdamato@fastly.com> References: <20240125003014.43103-1-jdamato@fastly.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Allow busy polling on a per-epoll context basis. The per-epoll context usec timeout value is preferred, but the pre-existing system wide sysctl value is still supported if it specified. Note that this change uses an xor: either per epoll instance busy polling is enabled on the epoll instance or system wide epoll is enabled. Enabling both is disallowed. Signed-off-by: Joe Damato --- fs/eventpoll.c | 49 +++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 45 insertions(+), 4 deletions(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 3534d36a1474..4503fec01278 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -227,6 +227,8 @@ struct eventpoll { #ifdef CONFIG_NET_RX_BUSY_POLL /* used to track busy poll napi_id */ unsigned int napi_id; + /* busy poll timeout */ + u64 busy_poll_usecs; #endif =20 #ifdef CONFIG_DEBUG_LOCK_ALLOC @@ -386,12 +388,44 @@ static inline int ep_events_available(struct eventpol= l *ep) READ_ONCE(ep->ovflist) !=3D EP_UNACTIVE_PTR; } =20 +/** + * busy_loop_ep_timeout - check if busy poll has timed out. The timeout va= lue + * from the epoll instance ep is preferred, but if it is not set fallback = to + * the system-wide global via busy_loop_timeout. + * + * @start_time: The start time used to compute the remaining time until ti= meout. + * @ep: Pointer to the eventpoll context. + * + * Return: true if the timeout has expired, false otherwise. + */ +static inline bool busy_loop_ep_timeout(unsigned long start_time, struct e= ventpoll *ep) +{ +#ifdef CONFIG_NET_RX_BUSY_POLL + unsigned long bp_usec =3D READ_ONCE(ep->busy_poll_usecs); + + if (bp_usec) { + unsigned long end_time =3D start_time + bp_usec; + unsigned long now =3D busy_loop_current_time(); + + return time_after(now, end_time); + } else { + return busy_loop_timeout(start_time); + } +#endif + return true; +} + #ifdef CONFIG_NET_RX_BUSY_POLL +static bool ep_busy_loop_on(struct eventpoll *ep) +{ + return !!ep->busy_poll_usecs ^ net_busy_loop_on(); +} + static bool ep_busy_loop_end(void *p, unsigned long start_time) { struct eventpoll *ep =3D p; =20 - return ep_events_available(ep) || busy_loop_timeout(start_time); + return ep_events_available(ep) || busy_loop_ep_timeout(start_time, ep); } =20 /* @@ -404,7 +438,7 @@ static bool ep_busy_loop(struct eventpoll *ep, int nonb= lock) { unsigned int napi_id =3D READ_ONCE(ep->napi_id); =20 - if ((napi_id >=3D MIN_NAPI_ID) && net_busy_loop_on()) { + if ((napi_id >=3D MIN_NAPI_ID) && ep_busy_loop_on(ep)) { napi_busy_loop(napi_id, nonblock ? NULL : ep_busy_loop_end, ep, false, BUSY_POLL_BUDGET); if (ep_events_available(ep)) @@ -430,7 +464,8 @@ static inline void ep_set_busy_poll_napi_id(struct epit= em *epi) struct socket *sock; struct sock *sk; =20 - if (!net_busy_loop_on()) + ep =3D epi->ep; + if (!ep_busy_loop_on(ep)) return; =20 sock =3D sock_from_file(epi->ffd.file); @@ -442,7 +477,6 @@ static inline void ep_set_busy_poll_napi_id(struct epit= em *epi) return; =20 napi_id =3D READ_ONCE(sk->sk_napi_id); - ep =3D epi->ep; =20 /* Non-NAPI IDs can be rejected * or @@ -466,6 +500,10 @@ static inline void ep_set_busy_poll_napi_id(struct epi= tem *epi) { } =20 +static inline bool ep_busy_loop_on(struct eventpoll *ep) +{ + return false; +} #endif /* CONFIG_NET_RX_BUSY_POLL */ =20 /* @@ -2058,6 +2096,9 @@ static int do_epoll_create(int flags) error =3D PTR_ERR(file); goto out_free_fd; } +#ifdef CONFIG_NET_RX_BUSY_POLL + ep->busy_poll_usecs =3D 0; +#endif ep->file =3D file; fd_install(fd, file); return fd; --=20 2.25.1 From nobody Wed Dec 24 18:19:16 2025 Received: from mail-ot1-f53.google.com (mail-ot1-f53.google.com [209.85.210.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B605A17EF for ; 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Wed, 24 Jan 2024 16:30:23 -0800 (PST) Received: from localhost.localdomain ([2620:11a:c018:0:ea8:be91:8d1:f59b]) by smtp.gmail.com with ESMTPSA id w10-20020a63d74a000000b005cd945c0399sm12550486pgi.80.2024.01.24.16.30.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jan 2024 16:30:23 -0800 (PST) From: Joe Damato To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: chuck.lever@oracle.com, jlayton@kernel.org, linux-api@vger.kernel.org, brauner@kernel.org, edumazet@google.com, davem@davemloft.net, alexander.duyck@gmail.com, sridhar.samudrala@intel.com, kuba@kernel.org, weiwan@google.com, Joe Damato Subject: [net-next v2 2/4] eventpoll: Add per-epoll busy poll packet budget Date: Thu, 25 Jan 2024 00:30:12 +0000 Message-Id: <20240125003014.43103-3-jdamato@fastly.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240125003014.43103-1-jdamato@fastly.com> References: <20240125003014.43103-1-jdamato@fastly.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When using epoll-based busy poll, the packet budget is hardcoded to BUSY_POLL_BUDGET (8). Users may desire larger busy poll budgets, which can potentially increase throughput when busy polling under high network load. Other busy poll methods allow setting the busy poll budget via SO_BUSY_POLL_BUDGET, but epoll-based busy polling uses a hardcoded value. Fix this edge case by adding support for a per-epoll context busy poll packet budget. If not specified, the default value (BUSY_POLL_BUDGET) is used. Signed-off-by: Joe Damato --- fs/eventpoll.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 4503fec01278..40bd97477b91 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -229,6 +229,8 @@ struct eventpoll { unsigned int napi_id; /* busy poll timeout */ u64 busy_poll_usecs; + /* busy poll packet budget */ + u16 busy_poll_budget; #endif =20 #ifdef CONFIG_DEBUG_LOCK_ALLOC @@ -437,10 +439,14 @@ static bool ep_busy_loop_end(void *p, unsigned long s= tart_time) static bool ep_busy_loop(struct eventpoll *ep, int nonblock) { unsigned int napi_id =3D READ_ONCE(ep->napi_id); + u16 budget =3D READ_ONCE(ep->busy_poll_budget); + + if (!budget) + budget =3D BUSY_POLL_BUDGET; =20 if ((napi_id >=3D MIN_NAPI_ID) && ep_busy_loop_on(ep)) { napi_busy_loop(napi_id, nonblock ? 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User programs can use this ioctl to get and set the busy poll usec time or packet budget params for a specific epoll context. Signed-off-by: Joe Damato --- .../userspace-api/ioctl/ioctl-number.rst | 1 + fs/eventpoll.c | 47 +++++++++++++++++++ include/uapi/linux/eventpoll.h | 12 +++++ 3 files changed, 60 insertions(+) diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documenta= tion/userspace-api/ioctl/ioctl-number.rst index 457e16f06e04..b33918232f78 100644 --- a/Documentation/userspace-api/ioctl/ioctl-number.rst +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst @@ -309,6 +309,7 @@ Code Seq# Include File = Comments 0x89 0B-DF linux/sockios.h 0x89 E0-EF linux/sockios.h SIOCP= ROTOPRIVATE range 0x89 F0-FF linux/sockios.h SIOCD= EVPRIVATE range +0x8A 00-1F linux/eventpoll.h 0x8B all linux/wireless.h 0x8C 00-3F WiNRA= DiO driver diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 40bd97477b91..c1ee0fe01da1 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -6,6 +6,8 @@ * Davide Libenzi */ =20 +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + #include #include #include @@ -869,6 +871,49 @@ static void ep_clear_and_put(struct eventpoll *ep) ep_free(ep); } =20 +static long ep_eventpoll_ioctl(struct file *file, unsigned int cmd, unsign= ed long arg) +{ + int ret; + struct eventpoll *ep; + struct epoll_params epoll_params; + void __user *uarg =3D (void __user *) arg; + + if (!is_file_epoll(file)) + return -EINVAL; + + ep =3D file->private_data; + + switch (cmd) { +#ifdef CONFIG_NET_RX_BUSY_POLL + case EPIOCSPARAMS: + if (copy_from_user(&epoll_params, uarg, sizeof(epoll_params))) + return -EFAULT; + + if (epoll_params.busy_poll_budget > NAPI_POLL_WEIGHT) + pr_err("busy poll budget %u exceeds suggested maximum %u\n", + epoll_params.busy_poll_budget, NAPI_POLL_WEIGHT); + + ep->busy_poll_usecs =3D epoll_params.busy_poll_usecs; + ep->busy_poll_budget =3D epoll_params.busy_poll_budget; + return 0; + + case EPIOCGPARAMS: + memset(&epoll_params, 0, sizeof(epoll_params)); + epoll_params.busy_poll_usecs =3D ep->busy_poll_usecs; + epoll_params.busy_poll_budget =3D ep->busy_poll_budget; + if (copy_to_user(uarg, &epoll_params, sizeof(epoll_params))) + return -EFAULT; + + return 0; +#endif + default: + ret =3D -EINVAL; + break; + } + + return ret; +} + static int ep_eventpoll_release(struct inode *inode, struct file *file) { struct eventpoll *ep =3D file->private_data; @@ -975,6 +1020,8 @@ static const struct file_operations eventpoll_fops =3D= { .release =3D ep_eventpoll_release, .poll =3D ep_eventpoll_poll, .llseek =3D noop_llseek, + .unlocked_ioctl =3D ep_eventpoll_ioctl, + .compat_ioctl =3D compat_ptr_ioctl, }; =20 /* diff --git a/include/uapi/linux/eventpoll.h b/include/uapi/linux/eventpoll.h index cfbcc4cc49ac..8eb0fdbce995 100644 --- a/include/uapi/linux/eventpoll.h +++ b/include/uapi/linux/eventpoll.h @@ -85,4 +85,16 @@ struct epoll_event { __u64 data; } EPOLL_PACKED; =20 +struct epoll_params { + u64 busy_poll_usecs; + u16 busy_poll_budget; + + /* for future fields */ + u8 data[118]; +} EPOLL_PACKED; + +#define EPOLL_IOC_TYPE 0x8A +#define EPIOCSPARAMS _IOW(EPOLL_IOC_TYPE, 0x01, struct epoll_params) +#define EPIOCGPARAMS _IOR(EPOLL_IOC_TYPE, 0x02, struct epoll_params) + #endif /* _UAPI_LINUX_EVENTPOLL_H */ --=20 2.25.1 From nobody Wed Dec 24 18:19:16 2025 Received: from mail-il1-f175.google.com (mail-il1-f175.google.com [209.85.166.175]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2626F67C5D for ; 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Wed, 24 Jan 2024 16:30:26 -0800 (PST) Received: from localhost.localdomain ([2620:11a:c018:0:ea8:be91:8d1:f59b]) by smtp.gmail.com with ESMTPSA id w10-20020a63d74a000000b005cd945c0399sm12550486pgi.80.2024.01.24.16.30.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jan 2024 16:30:26 -0800 (PST) From: Joe Damato To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: chuck.lever@oracle.com, jlayton@kernel.org, linux-api@vger.kernel.org, brauner@kernel.org, edumazet@google.com, davem@davemloft.net, alexander.duyck@gmail.com, sridhar.samudrala@intel.com, kuba@kernel.org, weiwan@google.com, Joe Damato Subject: [net-next v2 4/4] net: print error if SO_BUSY_POLL_BUDGET is large Date: Thu, 25 Jan 2024 00:30:14 +0000 Message-Id: <20240125003014.43103-5-jdamato@fastly.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240125003014.43103-1-jdamato@fastly.com> References: <20240125003014.43103-1-jdamato@fastly.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When drivers call netif_napi_add_weight with a weight that is larger than NAPI_POLL_WEIGHT, the networking code allows the larger weight, but prints an error. Replicate this check for SO_BUSY_POLL_BUDGET; check if the user specified amount exceeds NAPI_POLL_WEIGHT, allow it anyway, but print an error. Signed-off-by: Joe Damato --- net/core/sock.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/core/sock.c b/net/core/sock.c index 158dbdebce6a..ed243bd0dd77 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1153,6 +1153,9 @@ int sk_setsockopt(struct sock *sk, int level, int opt= name, return -EPERM; if (val < 0 || val > U16_MAX) return -EINVAL; + if (val > NAPI_POLL_WEIGHT) + pr_err("SO_BUSY_POLL_BUDGET %u exceeds suggested maximum %u\n", val, + NAPI_POLL_WEIGHT); WRITE_ONCE(sk->sk_busy_poll_budget, val); return 0; #endif --=20 2.25.1