netdev - [PATCH 7/9] softirq,net: Use softirq_needs

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Date: Fri, 5 May 2023 19:33:13 +0800
From: Liu Jian <liujian56@...wei.com>
To: <corbet@....net>, <paulmck@...nel.org>, <frederic@...nel.org>,
	<quic_neeraju@...cinc.com>, <joel@...lfernandes.org>,
	<josh@...htriplett.org>, <boqun.feng@...il.com>, <rostedt@...dmis.org>,
	<mathieu.desnoyers@...icios.com>, <jiangshanlai@...il.com>,
	<qiang1.zhang@...el.com>, <jstultz@...gle.com>, <tglx@...utronix.de>,
	<sboyd@...nel.org>, <davem@...emloft.net>, <edumazet@...gle.com>,
	<kuba@...nel.org>, <pabeni@...hat.com>, <peterz@...radead.org>,
	<frankwoo@...gle.com>, <Rhinewuwu@...gle.com>
CC: <liujian56@...wei.com>, <linux-doc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <rcu@...r.kernel.org>,
	<netdev@...r.kernel.org>
Subject: [PATCH 7/9] softirq,net: Use softirq_needs_break()

From: Peter Zijlstra <peterz@...radead.org>

SoftIRQs provide their own timeout/break code now, use that.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Liu Jian <liujian56@...wei.com>
---
 Documentation/admin-guide/sysctl/net.rst | 11 +----------
 net/core/dev.c                           |  6 +-----
 net/core/dev.h                           |  1 -
 net/core/sysctl_net_core.c               |  8 --------
 4 files changed, 2 insertions(+), 24 deletions(-)

diff --git a/Documentation/admin-guide/sysctl/net.rst b/Documentation/admin-guide/sysctl/net.rst
index 466c560b0c30..095c60788c61 100644
--- a/Documentation/admin-guide/sysctl/net.rst
+++ b/Documentation/admin-guide/sysctl/net.rst
@@ -267,16 +267,7 @@ netdev_budget
 
 Maximum number of packets taken from all interfaces in one polling cycle (NAPI
 poll). In one polling cycle interfaces which are registered to polling are
-probed in a round-robin manner. Also, a polling cycle may not exceed
-netdev_budget_usecs microseconds, even if netdev_budget has not been
-exhausted.
-
-netdev_budget_usecs
----------------------
-
-Maximum number of microseconds in one NAPI polling cycle. Polling
-will exit when either netdev_budget_usecs have elapsed during the
-poll cycle or the number of packets processed reaches netdev_budget.
+probed in a round-robin manner.
 
 netdev_max_backlog
 ------------------
diff --git a/net/core/dev.c b/net/core/dev.c
index 735096d42c1d..70b6726beee6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4321,7 +4321,6 @@ int netdev_tstamp_prequeue __read_mostly = 1;
 unsigned int sysctl_skb_defer_max __read_mostly = 64;
 int netdev_budget __read_mostly = 300;
 /* Must be at least 2 jiffes to guarantee 1 jiffy timeout */
-unsigned int __read_mostly netdev_budget_usecs = 2 * USEC_PER_SEC / HZ;
 int weight_p __read_mostly = 64;           /* old backlog weight */
 int dev_weight_rx_bias __read_mostly = 1;  /* bias for backlog weight */
 int dev_weight_tx_bias __read_mostly = 1;  /* bias for output_queue quota */
@@ -6659,8 +6658,6 @@ static int napi_threaded_poll(void *data)
 static __latent_entropy void net_rx_action(struct softirq_action *h)
 {
 	struct softnet_data *sd = this_cpu_ptr(&softnet_data);
-	unsigned long time_limit = jiffies +
-		usecs_to_jiffies(READ_ONCE(netdev_budget_usecs));
 	int budget = READ_ONCE(netdev_budget);
 	LIST_HEAD(list);
 	LIST_HEAD(repoll);
@@ -6699,8 +6696,7 @@ static __latent_entropy void net_rx_action(struct softirq_action *h)
 		 * Allow this to run for 2 jiffies since which will allow
 		 * an average latency of 1.5/HZ.
 		 */
-		if (unlikely(budget <= 0 ||
-			     time_after_eq(jiffies, time_limit))) {
+		if (unlikely(budget <= 0 || softirq_needs_break(h))) {
 			sd->time_squeeze++;
 			break;
 		}
diff --git a/net/core/dev.h b/net/core/dev.h
index e075e198092c..e64a60c767ab 100644
--- a/net/core/dev.h
+++ b/net/core/dev.h
@@ -39,7 +39,6 @@ void dev_addr_check(struct net_device *dev);
 
 /* sysctls not referred to from outside net/core/ */
 extern int		netdev_budget;
-extern unsigned int	netdev_budget_usecs;
 extern unsigned int	sysctl_skb_defer_max;
 extern int		netdev_tstamp_prequeue;
 extern int		netdev_unregister_timeout_secs;
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 782273bb93c2..59765c805f5b 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -595,14 +595,6 @@ static struct ctl_table net_core_table[] = {
 		.extra1		= SYSCTL_ONE,
 		.extra2		= &max_skb_frags,
 	},
-	{
-		.procname	= "netdev_budget_usecs",
-		.data		= &netdev_budget_usecs,
-		.maxlen		= sizeof(unsigned int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
-	},
 	{
 		.procname	= "fb_tunnels_only_for_init_net",
 		.data		= &sysctl_fb_tunnels_only_for_init_net,
-- 
2.34.1