Commit 34008d8c authored by Stephen Hemminger's avatar Stephen Hemminger Committed by David S. Miller
Browse files

[NET]: Remove obsolete netif_rx congestion sensing mechanism. 



Remove the congestion sensing mechanism from netif_rx, and always
return either full or empty.  Almost no driver checks the return value
from netif_rx, and those that do only use it for debug messages.

The original design of netif_rx was to do flow control based on the
receive queue, but NAPI has supplanted this and no driver uses the
feedback.

Signed-off-by: default avatarStephen Hemminger <shemminger@osdl.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c1ebcdb8

include/linux/netdevice.h

+0 −2
Original line number Diff line number Diff line
@@ -558,8 +558,6 @@ static inline int unregister_gifconf(unsigned int family) 
struct softnet_data

{

	int			throttle;

	int			cng_level;

	int			avg_blog;

	struct sk_buff_head	input_pkt_queue;

	struct list_head	poll_list;

	struct net_device	*output_queue;

net/core/dev.c

+1 −87
Original line number Diff line number Diff line
@@ -115,18 +115,6 @@ 
#endif	/* CONFIG_NET_RADIO */

#include <asm/current.h>



/* This define, if set, will randomly drop a packet when congestion

 * is more than moderate.  It helps fairness in the multi-interface

 * case when one of them is a hog, but it kills performance for the

 * single interface case so it is off now by default.

 */

#undef RAND_LIE



/* Setting this will sample the queue lengths and thus congestion

 * via a timer instead of as each packet is received.

 */

#undef OFFLINE_SAMPLE



/*

 *	The list of packet types we will receive (as opposed to discard)

 *	and the routines to invoke.
@@ -159,11 +147,6 @@ static DEFINE_SPINLOCK(ptype_lock); 
static struct list_head ptype_base[16];	/* 16 way hashed list */

static struct list_head ptype_all;		/* Taps */



#ifdef OFFLINE_SAMPLE

static void sample_queue(unsigned long dummy);

static struct timer_list samp_timer = TIMER_INITIALIZER(sample_queue, 0, 0);

#endif



/*

 * The @dev_base list is protected by @dev_base_lock and the rtln

 * semaphore.
@@ -1365,69 +1348,10 @@ out: 


int netdev_max_backlog = 300;

int weight_p = 64;            /* old backlog weight */

/* These numbers are selected based on intuition and some

 * experimentatiom, if you have more scientific way of doing this

 * please go ahead and fix things.

 */

int no_cong_thresh = 10;

int no_cong = 20;

int lo_cong = 100;

int mod_cong = 290;



DEFINE_PER_CPU(struct netif_rx_stats, netdev_rx_stat) = { 0, };





static void get_sample_stats(int cpu)

{

#ifdef RAND_LIE

	unsigned long rd;

	int rq;

#endif

	struct softnet_data *sd = &per_cpu(softnet_data, cpu);

	int blog = sd->input_pkt_queue.qlen;

	int avg_blog = sd->avg_blog;



	avg_blog = (avg_blog >> 1) + (blog >> 1);



	if (avg_blog > mod_cong) {

		/* Above moderate congestion levels. */

		sd->cng_level = NET_RX_CN_HIGH;

#ifdef RAND_LIE

		rd = net_random();

		rq = rd % netdev_max_backlog;

		if (rq < avg_blog) /* unlucky bastard */

			sd->cng_level = NET_RX_DROP;

#endif

	} else if (avg_blog > lo_cong) {

		sd->cng_level = NET_RX_CN_MOD;

#ifdef RAND_LIE

		rd = net_random();

		rq = rd % netdev_max_backlog;

			if (rq < avg_blog) /* unlucky bastard */

				sd->cng_level = NET_RX_CN_HIGH;

#endif

	} else if (avg_blog > no_cong)

		sd->cng_level = NET_RX_CN_LOW;

	else  /* no congestion */

		sd->cng_level = NET_RX_SUCCESS;



	sd->avg_blog = avg_blog;

}



#ifdef OFFLINE_SAMPLE

static void sample_queue(unsigned long dummy)

{

/* 10 ms 0r 1ms -- i don't care -- JHS */

	int next_tick = 1;

	int cpu = smp_processor_id();



	get_sample_stats(cpu);

	next_tick += jiffies;

	mod_timer(&samp_timer, next_tick);

}

#endif





/**

 *	netif_rx	-	post buffer to the network code

 *	@skb: buffer to post
@@ -1476,11 +1400,8 @@ int netif_rx(struct sk_buff *skb) 
enqueue:

			dev_hold(skb->dev);

			__skb_queue_tail(&queue->input_pkt_queue, skb);

#ifndef OFFLINE_SAMPLE

			get_sample_stats(this_cpu);

#endif

			local_irq_restore(flags);

			return queue->cng_level;

			return NET_RX_SUCCESS;

		}



		if (queue->throttle)
@@ -3300,8 +3221,6 @@ static int __init net_dev_init(void) 
		queue = &per_cpu(softnet_data, i);

		skb_queue_head_init(&queue->input_pkt_queue);

		queue->throttle = 0;

		queue->cng_level = 0;

		queue->avg_blog = 10; /* arbitrary non-zero */

		queue->completion_queue = NULL;

		INIT_LIST_HEAD(&queue->poll_list);

		set_bit(__LINK_STATE_START, &queue->backlog_dev.state);
@@ -3310,11 +3229,6 @@ static int __init net_dev_init(void) 
		atomic_set(&queue->backlog_dev.refcnt, 1);

	}



#ifdef OFFLINE_SAMPLE

	samp_timer.expires = jiffies + (10 * HZ);

	add_timer(&samp_timer);

#endif



	dev_boot_phase = 0;



	open_softirq(NET_TX_SOFTIRQ, net_tx_action, NULL);

net/core/sysctl_net_core.c

+0 −36
Original line number Diff line number Diff line
@@ -14,10 +14,6 @@ 


extern int netdev_max_backlog;

extern int weight_p;

extern int no_cong_thresh;

extern int no_cong;

extern int lo_cong;

extern int mod_cong;

extern int net_msg_cost;

extern int net_msg_burst;
@@ -84,38 +80,6 @@ ctl_table core_table[] = { 
		.mode		= 0644,

		.proc_handler	= &proc_dointvec

	},

	{

		.ctl_name	= NET_CORE_NO_CONG_THRESH,

		.procname	= "no_cong_thresh",

		.data		= &no_cong_thresh,

		.maxlen		= sizeof(int),

		.mode		= 0644,

		.proc_handler	= &proc_dointvec

	},

	{

		.ctl_name	= NET_CORE_NO_CONG,

		.procname	= "no_cong",

		.data		= &no_cong,

		.maxlen		= sizeof(int),

		.mode		= 0644,

		.proc_handler	= &proc_dointvec

	},

	{

		.ctl_name	= NET_CORE_LO_CONG,

		.procname	= "lo_cong",

		.data		= &lo_cong,

		.maxlen		= sizeof(int),

		.mode		= 0644,

		.proc_handler	= &proc_dointvec

	},

	{

		.ctl_name	= NET_CORE_MOD_CONG,

		.procname	= "mod_cong",

		.data		= &mod_cong,

		.maxlen		= sizeof(int),

		.mode		= 0644,

		.proc_handler	= &proc_dointvec

	},

	{

		.ctl_name	= NET_CORE_MSG_COST,

		.procname	= "message_cost",

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