net: move dev_rx_weight to net_hotdata

dev_rx_weight is read from process_backlog().

Move it to net_hotdata for better cache locality.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20240306160031.874438-10-edumazet@google.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

include/linux/netdevice.h

@@ -4793,8 +4793,6 @@ void dev_fetch_sw_netstats(struct rtnl_link_stats64 *s,
 			   const struct pcpu_sw_netstats __percpu *netstats);
 void dev_get_tstats64(struct net_device *dev, struct rtnl_link_stats64 *s);
 
-extern int		dev_rx_weight;
-
 enum {
 	NESTED_SYNC_IMM_BIT,
 	NESTED_SYNC_TODO_BIT,

include/net/hotdata.h

@@ -22,6 +22,7 @@ struct net_hotdata {
 	int			tstamp_prequeue;
 	int			max_backlog;
 	int			dev_tx_weight;
+	int			dev_rx_weight;
 };
 
 extern struct net_hotdata net_hotdata;

net/core/dev.c

@@ -4408,7 +4408,6 @@ unsigned int sysctl_skb_defer_max __read_mostly = 64;
 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 */
-int dev_rx_weight __read_mostly = 64;
 
 /* Called with irq disabled */
 static inline void ____napi_schedule(struct softnet_data *sd,
@@ -5978,7 +5977,7 @@ static int process_backlog(struct napi_struct *napi, int quota)
 		net_rps_action_and_irq_enable(sd);
 	}
 
-	napi->weight = READ_ONCE(dev_rx_weight);
+	napi->weight = READ_ONCE(net_hotdata.dev_rx_weight);
 	while (again) {
 		struct sk_buff *skb;
 

net/core/hotdata.c

@@ -17,5 +17,6 @@ struct net_hotdata net_hotdata __cacheline_aligned = {
 	.tstamp_prequeue = 1,
 	.max_backlog = 1000,
 	.dev_tx_weight = 64,
+	.dev_rx_weight = 64,
 };
 EXPORT_SYMBOL(net_hotdata);

net/core/sysctl_net_core.c

@@ -301,7 +301,7 @@ static int proc_do_dev_weight(struct ctl_table *table, int write,
 	ret = proc_dointvec(table, write, buffer, lenp, ppos);
 	if (!ret && write) {
 		weight = READ_ONCE(weight_p);
-		WRITE_ONCE(dev_rx_weight, weight * dev_weight_rx_bias);
+		WRITE_ONCE(net_hotdata.dev_rx_weight, weight * dev_weight_rx_bias);
 		WRITE_ONCE(net_hotdata.dev_tx_weight, weight * dev_weight_tx_bias);
 	}
 	mutex_unlock(&dev_weight_mutex);