2019-05-30 07:57:49 +08:00
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/* SPDX-License-Identifier: GPL-2.0-only */
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2013-06-10 16:39:50 +08:00
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/*
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2013-07-10 22:13:26 +08:00
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* net busy poll support
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2013-06-10 16:39:50 +08:00
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* Copyright(c) 2013 Intel Corporation.
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*
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* Author: Eliezer Tamir
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*
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* Contact Information:
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* e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>
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*/
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2013-07-10 22:13:26 +08:00
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#ifndef _LINUX_NET_BUSY_POLL_H
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#define _LINUX_NET_BUSY_POLL_H
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2013-06-10 16:39:50 +08:00
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#include <linux/netdevice.h>
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2017-02-01 23:36:40 +08:00
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#include <linux/sched/clock.h>
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2017-02-03 02:15:33 +08:00
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#include <linux/sched/signal.h>
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2013-06-10 16:39:50 +08:00
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#include <net/ip.h>
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2017-03-25 01:07:53 +08:00
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/* 0 - Reserved to indicate value not set
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* 1..NR_CPUS - Reserved for sender_cpu
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* NR_CPUS+1..~0 - Region available for NAPI IDs
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*/
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#define MIN_NAPI_ID ((unsigned int)(NR_CPUS + 1))
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2020-12-01 02:51:57 +08:00
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#define BUSY_POLL_BUDGET 8
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2017-08-12 00:31:24 +08:00
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#ifdef CONFIG_NET_RX_BUSY_POLL
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struct napi_struct;
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extern unsigned int sysctl_net_busy_read __read_mostly;
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extern unsigned int sysctl_net_busy_poll __read_mostly;
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2013-07-08 21:20:34 +08:00
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static inline bool net_busy_loop_on(void)
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2013-06-28 20:59:35 +08:00
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{
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2013-07-10 22:13:36 +08:00
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return sysctl_net_busy_poll;
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2013-06-28 20:59:35 +08:00
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}
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2017-03-25 01:08:18 +08:00
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static inline bool sk_can_busy_loop(const struct sock *sk)
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2013-06-28 20:59:26 +08:00
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{
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2017-03-25 01:08:18 +08:00
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return sk->sk_ll_usec && !signal_pending(current);
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2013-06-28 20:59:26 +08:00
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}
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2017-03-25 01:08:24 +08:00
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bool sk_busy_loop_end(void *p, unsigned long start_time);
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void napi_busy_loop(unsigned int napi_id,
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bool (*loop_end)(void *, unsigned long),
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2020-12-01 02:51:57 +08:00
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void *loop_end_arg, bool prefer_busy_poll, u16 budget);
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2013-06-14 21:33:35 +08:00
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2017-03-25 01:08:18 +08:00
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#else /* CONFIG_NET_RX_BUSY_POLL */
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static inline unsigned long net_busy_loop_on(void)
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2013-07-03 04:22:47 +08:00
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{
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2017-03-25 01:08:18 +08:00
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return 0;
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2013-06-10 16:39:50 +08:00
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}
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2017-03-25 01:08:18 +08:00
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static inline bool sk_can_busy_loop(struct sock *sk)
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2013-06-10 16:39:50 +08:00
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{
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2017-03-25 01:08:18 +08:00
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return false;
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2013-06-10 16:39:50 +08:00
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}
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2017-03-25 01:08:18 +08:00
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#endif /* CONFIG_NET_RX_BUSY_POLL */
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2013-06-10 16:39:50 +08:00
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2017-03-25 01:08:18 +08:00
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static inline unsigned long busy_loop_current_time(void)
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2013-06-28 20:59:35 +08:00
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{
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2017-03-25 01:08:18 +08:00
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#ifdef CONFIG_NET_RX_BUSY_POLL
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return (unsigned long)(local_clock() >> 10);
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#else
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2013-06-28 20:59:35 +08:00
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return 0;
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2017-03-25 01:08:18 +08:00
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#endif
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2013-06-28 20:59:35 +08:00
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}
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2013-06-10 16:39:50 +08:00
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2017-03-25 01:08:18 +08:00
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/* in poll/select we use the global sysctl_net_ll_poll value */
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static inline bool busy_loop_timeout(unsigned long start_time)
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2013-06-10 16:39:50 +08:00
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{
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2017-03-25 01:08:18 +08:00
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#ifdef CONFIG_NET_RX_BUSY_POLL
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unsigned long bp_usec = READ_ONCE(sysctl_net_busy_poll);
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2013-06-10 16:39:50 +08:00
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2017-03-25 01:08:18 +08:00
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if (bp_usec) {
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unsigned long end_time = start_time + bp_usec;
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unsigned long now = busy_loop_current_time();
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2013-06-10 16:39:50 +08:00
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2017-03-25 01:08:18 +08:00
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return time_after(now, end_time);
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}
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#endif
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2013-07-09 18:09:21 +08:00
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return true;
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2013-06-10 16:39:50 +08:00
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}
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2017-03-25 01:08:18 +08:00
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static inline bool sk_busy_loop_timeout(struct sock *sk,
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unsigned long start_time)
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2013-08-01 11:10:24 +08:00
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{
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2017-03-25 01:08:18 +08:00
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#ifdef CONFIG_NET_RX_BUSY_POLL
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unsigned long bp_usec = READ_ONCE(sk->sk_ll_usec);
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2013-08-01 11:10:24 +08:00
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2017-03-25 01:08:18 +08:00
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if (bp_usec) {
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unsigned long end_time = start_time + bp_usec;
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unsigned long now = busy_loop_current_time();
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return time_after(now, end_time);
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}
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#endif
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return true;
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}
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2016-11-17 01:10:42 +08:00
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2017-03-25 01:08:24 +08:00
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static inline void sk_busy_loop(struct sock *sk, int nonblock)
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{
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#ifdef CONFIG_NET_RX_BUSY_POLL
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unsigned int napi_id = READ_ONCE(sk->sk_napi_id);
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if (napi_id >= MIN_NAPI_ID)
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net: Introduce preferred busy-polling
The existing busy-polling mode, enabled by the SO_BUSY_POLL socket
option or system-wide using the /proc/sys/net/core/busy_read knob, is
an opportunistic. That means that if the NAPI context is not
scheduled, it will poll it. If, after busy-polling, the budget is
exceeded the busy-polling logic will schedule the NAPI onto the
regular softirq handling.
One implication of the behavior above is that a busy/heavy loaded NAPI
context will never enter/allow for busy-polling. Some applications
prefer that most NAPI processing would be done by busy-polling.
This series adds a new socket option, SO_PREFER_BUSY_POLL, that works
in concert with the napi_defer_hard_irqs and gro_flush_timeout
knobs. The napi_defer_hard_irqs and gro_flush_timeout knobs were
introduced in commit 6f8b12d661d0 ("net: napi: add hard irqs deferral
feature"), and allows for a user to defer interrupts to be enabled and
instead schedule the NAPI context from a watchdog timer. When a user
enables the SO_PREFER_BUSY_POLL, again with the other knobs enabled,
and the NAPI context is being processed by a softirq, the softirq NAPI
processing will exit early to allow the busy-polling to be performed.
If the application stops performing busy-polling via a system call,
the watchdog timer defined by gro_flush_timeout will timeout, and
regular softirq handling will resume.
In summary; Heavy traffic applications that prefer busy-polling over
softirq processing should use this option.
Example usage:
$ echo 2 | sudo tee /sys/class/net/ens785f1/napi_defer_hard_irqs
$ echo 200000 | sudo tee /sys/class/net/ens785f1/gro_flush_timeout
Note that the timeout should be larger than the userspace processing
window, otherwise the watchdog will timeout and fall back to regular
softirq processing.
Enable the SO_BUSY_POLL/SO_PREFER_BUSY_POLL options on your socket.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/bpf/20201130185205.196029-2-bjorn.topel@gmail.com
2020-12-01 02:51:56 +08:00
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napi_busy_loop(napi_id, nonblock ? NULL : sk_busy_loop_end, sk,
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2020-12-01 02:51:57 +08:00
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READ_ONCE(sk->sk_prefer_busy_poll),
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READ_ONCE(sk->sk_busy_poll_budget) ?: BUSY_POLL_BUDGET);
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2017-03-25 01:08:24 +08:00
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#endif
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}
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2017-03-25 01:08:06 +08:00
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/* used in the NIC receive handler to mark the skb */
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static inline void skb_mark_napi_id(struct sk_buff *skb,
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struct napi_struct *napi)
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{
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#ifdef CONFIG_NET_RX_BUSY_POLL
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2020-06-19 05:22:15 +08:00
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/* If the skb was already marked with a valid NAPI ID, avoid overwriting
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* it.
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*/
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if (skb->napi_id < MIN_NAPI_ID)
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skb->napi_id = napi->napi_id;
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2017-03-25 01:08:06 +08:00
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#endif
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}
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2016-11-17 01:10:42 +08:00
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/* used in the protocol hanlder to propagate the napi_id to the socket */
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static inline void sk_mark_napi_id(struct sock *sk, const struct sk_buff *skb)
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{
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#ifdef CONFIG_NET_RX_BUSY_POLL
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2019-10-30 01:54:44 +08:00
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WRITE_ONCE(sk->sk_napi_id, skb->napi_id);
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2016-11-17 01:10:42 +08:00
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#endif
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2018-06-30 12:26:57 +08:00
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sk_rx_queue_set(sk, skb);
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2016-11-17 01:10:42 +08:00
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}
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2020-12-01 22:22:59 +08:00
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static inline void __sk_mark_napi_id_once(struct sock *sk, unsigned int napi_id)
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2016-11-17 01:10:42 +08:00
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{
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#ifdef CONFIG_NET_RX_BUSY_POLL
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2019-10-30 01:54:44 +08:00
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if (!READ_ONCE(sk->sk_napi_id))
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2020-12-01 02:52:01 +08:00
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WRITE_ONCE(sk->sk_napi_id, napi_id);
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2016-11-17 01:10:42 +08:00
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#endif
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}
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2020-12-01 02:52:01 +08:00
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/* variant used for unconnected sockets */
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static inline void sk_mark_napi_id_once(struct sock *sk,
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const struct sk_buff *skb)
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{
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2020-12-01 22:22:59 +08:00
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#ifdef CONFIG_NET_RX_BUSY_POLL
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__sk_mark_napi_id_once(sk, skb->napi_id);
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#endif
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2020-12-01 02:52:01 +08:00
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}
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static inline void sk_mark_napi_id_once_xdp(struct sock *sk,
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const struct xdp_buff *xdp)
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{
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2020-12-01 22:22:59 +08:00
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#ifdef CONFIG_NET_RX_BUSY_POLL
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__sk_mark_napi_id_once(sk, xdp->rxq->napi_id);
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#endif
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2020-12-01 02:52:01 +08:00
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}
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2013-07-10 22:13:26 +08:00
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#endif /* _LINUX_NET_BUSY_POLL_H */
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