net/dccp/ccids/lib/loss_interval.c - maze/linux - Git at Google

 /*
  *  net/dccp/ccids/lib/loss_interval.c
  *
  *  Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
  *  Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz>
  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation; either version 2 of the License, or
  *  (at your option) any later version.
  */

 #include <linux/module.h>
 #include <net/sock.h>
 #include "../../dccp.h"
 #include "loss_interval.h"
 #include "packet_history.h"
 #include "tfrc.h"

 #define DCCP_LI_HIST_IVAL_F_LENGTH  8

 struct dccp_li_hist_entry {
 	struct list_head dccplih_node;
 	u64		 dccplih_seqno:48,
 			 dccplih_win_count:4;
 	u32		 dccplih_interval;
 };

 static struct kmem_cache *dccp_li_cachep __read_mostly;

 static inline struct dccp_li_hist_entry *dccp_li_hist_entry_new(const gfp_t prio)
 {
 	return kmem_cache_alloc(dccp_li_cachep, prio);
 }

 static inline void dccp_li_hist_entry_delete(struct dccp_li_hist_entry *entry)
 {
 	if (entry != NULL)
 		kmem_cache_free(dccp_li_cachep, entry);
 }

 void dccp_li_hist_purge(struct list_head *list)
 {
 	struct dccp_li_hist_entry *entry, *next;

 	list_for_each_entry_safe(entry, next, list, dccplih_node) {
 		list_del_init(&entry->dccplih_node);
 		kmem_cache_free(dccp_li_cachep, entry);
 	}
 }

 EXPORT_SYMBOL_GPL(dccp_li_hist_purge);

 /* Weights used to calculate loss event rate */
 /*
  * These are integers as per section 8 of RFC3448. We can then divide by 4 *
  * when we use it.
  */
 static const int dccp_li_hist_w[DCCP_LI_HIST_IVAL_F_LENGTH] = {
 	4, 4, 4, 4, 3, 2, 1, 1,
 };

 u32 dccp_li_hist_calc_i_mean(struct list_head *list)
 {
 	struct dccp_li_hist_entry *li_entry, *li_next;
 	int i = 0;
 	u32 i_tot;
 	u32 i_tot0 = 0;
 	u32 i_tot1 = 0;
 	u32 w_tot  = 0;

 	list_for_each_entry_safe(li_entry, li_next, list, dccplih_node) {
 		if (li_entry->dccplih_interval != ~0U) {
 			i_tot0 += li_entry->dccplih_interval * dccp_li_hist_w[i];
 			w_tot  += dccp_li_hist_w[i];
 			if (i != 0)
 				i_tot1 += li_entry->dccplih_interval * dccp_li_hist_w[i - 1];
 		}


 		if (++i > DCCP_LI_HIST_IVAL_F_LENGTH)
 			break;
 	}

 	if (i != DCCP_LI_HIST_IVAL_F_LENGTH)
 		return 0;

 	i_tot = max(i_tot0, i_tot1);

 	if (!w_tot) {
 		DCCP_WARN("w_tot = 0\n");
 		return 1;
 	}

 	return i_tot / w_tot;
 }

 EXPORT_SYMBOL_GPL(dccp_li_hist_calc_i_mean);

 static int dccp_li_hist_interval_new(struct list_head *list,
 				     const u64 seq_loss, const u8 win_loss)
 {
 	struct dccp_li_hist_entry *entry;
 	int i;

 	for (i = 0; i < DCCP_LI_HIST_IVAL_F_LENGTH; i++) {
 		entry = dccp_li_hist_entry_new(GFP_ATOMIC);
 		if (entry == NULL) {
 			dccp_li_hist_purge(list);
 			DCCP_BUG("loss interval list entry is NULL");
 			return 0;
 		}
 		entry->dccplih_interval = ~0;
 		list_add(&entry->dccplih_node, list);
 	}

 	entry->dccplih_seqno     = seq_loss;
 	entry->dccplih_win_count = win_loss;
 	return 1;
 }

 /* calculate first loss interval
  *
  * returns estimated loss interval in usecs */
 static u32 dccp_li_calc_first_li(struct sock *sk,
 				 struct list_head *hist_list,
 				 struct timeval *last_feedback,
 				 u16 s, u32 bytes_recv,
 				 u32 previous_x_recv)
 {
 	struct dccp_rx_hist_entry *entry, *next, *tail = NULL;
 	u32 x_recv, p;
 	suseconds_t rtt, delta;
 	struct timeval tstamp = { 0, 0 };
 	int interval = 0;
 	int win_count = 0;
 	int step = 0;
 	u64 fval;

 	list_for_each_entry_safe(entry, next, hist_list, dccphrx_node) {
 		if (dccp_rx_hist_entry_data_packet(entry)) {
 			tail = entry;

 			switch (step) {
 			case 0:
 				tstamp	  = entry->dccphrx_tstamp;
 				win_count = entry->dccphrx_ccval;
 				step = 1;
 				break;
 			case 1:
 				interval = win_count - entry->dccphrx_ccval;
 				if (interval < 0)
 					interval += TFRC_WIN_COUNT_LIMIT;
 				if (interval > 4)
 					goto found;
 				break;
 			}
 		}
 	}

 	if (unlikely(step == 0)) {
 		DCCP_WARN("%s(%p), packet history has no data packets!\n",
 			  dccp_role(sk), sk);
 		return ~0;
 	}

 	if (unlikely(interval == 0)) {
 		DCCP_WARN("%s(%p), Could not find a win_count interval > 0."
 			  "Defaulting to 1\n", dccp_role(sk), sk);
 		interval = 1;
 	}
 found:
 	if (!tail) {
 		DCCP_CRIT("tail is null\n");
 		return ~0;
 	}

 	delta = timeval_delta(&tstamp, &tail->dccphrx_tstamp);
 	DCCP_BUG_ON(delta < 0);

 	rtt = delta * 4 / interval;
 	dccp_pr_debug("%s(%p), approximated RTT to %dus\n",
 		      dccp_role(sk), sk, (int)rtt);

 	/*
 	 * Determine the length of the first loss interval via inverse lookup.
 	 * Assume that X_recv can be computed by the throughput equation
 	 *		    s
 	 *	X_recv = --------
 	 *		 R * fval
 	 * Find some p such that f(p) = fval; return 1/p [RFC 3448, 6.3.1].
 	 */
 	if (rtt == 0) {			/* would result in divide-by-zero */
 		DCCP_WARN("RTT==0\n");
 		return ~0;
 	}

 	dccp_timestamp(sk, &tstamp);
 	delta = timeval_delta(&tstamp, last_feedback);
 	DCCP_BUG_ON(delta <= 0);

 	x_recv = scaled_div32(bytes_recv, delta);
 	if (x_recv == 0) {		/* would also trigger divide-by-zero */
 		DCCP_WARN("X_recv==0\n");
 		if (previous_x_recv == 0) {
 			DCCP_BUG("stored value of X_recv is zero");
 			return ~0;
 		}
 		x_recv = previous_x_recv;
 	}

 	fval = scaled_div(s, rtt);
 	fval = scaled_div32(fval, x_recv);
 	p = tfrc_calc_x_reverse_lookup(fval);

 	dccp_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
 		      "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);

 	if (p == 0)
 		return ~0;
 	else
 		return 1000000 / p;
 }

 void dccp_li_update_li(struct sock *sk,
 		       struct list_head *li_hist_list,
 		       struct list_head *hist_list,
 		       struct timeval *last_feedback, u16 s, u32 bytes_recv,
 		       u32 previous_x_recv, u64 seq_loss, u8 win_loss)
 {
 	struct dccp_li_hist_entry *head;
 	u64 seq_temp;

 	if (list_empty(li_hist_list)) {
 		if (!dccp_li_hist_interval_new(li_hist_list, seq_loss,
 					       win_loss))
 			return;

 		head = list_entry(li_hist_list->next, struct dccp_li_hist_entry,
 				  dccplih_node);
 		head->dccplih_interval = dccp_li_calc_first_li(sk, hist_list,
 							       last_feedback,
 							       s, bytes_recv,
 							       previous_x_recv);
 	} else {
 		struct dccp_li_hist_entry *entry;
 		struct list_head *tail;

 		head = list_entry(li_hist_list->next, struct dccp_li_hist_entry,
 				  dccplih_node);
 		/* FIXME win count check removed as was wrong */
 		/* should make this check with receive history */
 		/* and compare there as per section 10.2 of RFC4342 */

 		/* new loss event detected */
 		/* calculate last interval length */
 		seq_temp = dccp_delta_seqno(head->dccplih_seqno, seq_loss);
 		entry = dccp_li_hist_entry_new(GFP_ATOMIC);

 		if (entry == NULL) {
 			DCCP_BUG("out of memory - can not allocate entry");
 			return;
 		}

 		list_add(&entry->dccplih_node, li_hist_list);

 		tail = li_hist_list->prev;
 		list_del(tail);
 		kmem_cache_free(dccp_li_cachep, tail);

 		/* Create the newest interval */
 		entry->dccplih_seqno = seq_loss;
 		entry->dccplih_interval = seq_temp;
 		entry->dccplih_win_count = win_loss;
 	}
 }

 EXPORT_SYMBOL_GPL(dccp_li_update_li);

 static __init int dccp_li_init(void)
 {
 	dccp_li_cachep = kmem_cache_create("dccp_li_hist",
 					   sizeof(struct dccp_li_hist_entry),
 					   0, SLAB_HWCACHE_ALIGN, NULL);
 	return dccp_li_cachep == NULL ? -ENOBUFS : 0;
 }

 static __exit void dccp_li_exit(void)
 {
 	kmem_cache_destroy(dccp_li_cachep);
 }

 module_init(dccp_li_init);
 module_exit(dccp_li_exit);
	/*
	* net/dccp/ccids/lib/loss_interval.c
	*
	* Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
	* Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz>
	* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*/

	#include <linux/module.h>
	#include <net/sock.h>
	#include "../../dccp.h"
	#include "loss_interval.h"
	#include "packet_history.h"
	#include "tfrc.h"

	#define DCCP_LI_HIST_IVAL_F_LENGTH 8

	struct dccp_li_hist_entry {
	struct list_head dccplih_node;
	u64 dccplih_seqno:48,
	dccplih_win_count:4;
	u32 dccplih_interval;
	};

	static struct kmem_cache *dccp_li_cachep __read_mostly;

	static inline struct dccp_li_hist_entry *dccp_li_hist_entry_new(const gfp_t prio)
	{
	return kmem_cache_alloc(dccp_li_cachep, prio);
	}

	static inline void dccp_li_hist_entry_delete(struct dccp_li_hist_entry *entry)
	{
	if (entry != NULL)
	kmem_cache_free(dccp_li_cachep, entry);
	}

	void dccp_li_hist_purge(struct list_head *list)
	{
	struct dccp_li_hist_entry entry, next;

	list_for_each_entry_safe(entry, next, list, dccplih_node) {
	list_del_init(&entry->dccplih_node);
	kmem_cache_free(dccp_li_cachep, entry);
	}
	}

	EXPORT_SYMBOL_GPL(dccp_li_hist_purge);

	/* Weights used to calculate loss event rate */
	/*
	* These are integers as per section 8 of RFC3448. We can then divide by 4 *
	* when we use it.
	*/
	static const int dccp_li_hist_w[DCCP_LI_HIST_IVAL_F_LENGTH] = {
	4, 4, 4, 4, 3, 2, 1, 1,
	};

	u32 dccp_li_hist_calc_i_mean(struct list_head *list)
	{
	struct dccp_li_hist_entry li_entry, li_next;
	int i = 0;
	u32 i_tot;
	u32 i_tot0 = 0;
	u32 i_tot1 = 0;
	u32 w_tot = 0;

	list_for_each_entry_safe(li_entry, li_next, list, dccplih_node) {
	if (li_entry->dccplih_interval != ~0U) {
	i_tot0 += li_entry->dccplih_interval * dccp_li_hist_w[i];
	w_tot += dccp_li_hist_w[i];
	if (i != 0)
	i_tot1 += li_entry->dccplih_interval * dccp_li_hist_w[i - 1];
	}


	if (++i > DCCP_LI_HIST_IVAL_F_LENGTH)
	break;
	}

	if (i != DCCP_LI_HIST_IVAL_F_LENGTH)
	return 0;

	i_tot = max(i_tot0, i_tot1);

	if (!w_tot) {
	DCCP_WARN("w_tot = 0\n");
	return 1;
	}

	return i_tot / w_tot;
	}

	EXPORT_SYMBOL_GPL(dccp_li_hist_calc_i_mean);

	static int dccp_li_hist_interval_new(struct list_head *list,
	const u64 seq_loss, const u8 win_loss)
	{
	struct dccp_li_hist_entry *entry;
	int i;

	for (i = 0; i < DCCP_LI_HIST_IVAL_F_LENGTH; i++) {
	entry = dccp_li_hist_entry_new(GFP_ATOMIC);
	if (entry == NULL) {
	dccp_li_hist_purge(list);
	DCCP_BUG("loss interval list entry is NULL");
	return 0;
	}
	entry->dccplih_interval = ~0;
	list_add(&entry->dccplih_node, list);
	}

	entry->dccplih_seqno = seq_loss;
	entry->dccplih_win_count = win_loss;
	return 1;
	}

	/* calculate first loss interval
	*
	* returns estimated loss interval in usecs */
	static u32 dccp_li_calc_first_li(struct sock *sk,
	struct list_head *hist_list,
	struct timeval *last_feedback,
	u16 s, u32 bytes_recv,
	u32 previous_x_recv)
	{
	struct dccp_rx_hist_entry entry, next, *tail = NULL;
	u32 x_recv, p;
	suseconds_t rtt, delta;
	struct timeval tstamp = { 0, 0 };
	int interval = 0;
	int win_count = 0;
	int step = 0;
	u64 fval;

	list_for_each_entry_safe(entry, next, hist_list, dccphrx_node) {
	if (dccp_rx_hist_entry_data_packet(entry)) {
	tail = entry;

	switch (step) {
	case 0:
	tstamp = entry->dccphrx_tstamp;
	win_count = entry->dccphrx_ccval;
	step = 1;
	break;
	case 1:
	interval = win_count - entry->dccphrx_ccval;
	if (interval < 0)
	interval += TFRC_WIN_COUNT_LIMIT;
	if (interval > 4)
	goto found;
	break;
	}
	}
	}

	if (unlikely(step == 0)) {
	DCCP_WARN("%s(%p), packet history has no data packets!\n",
	dccp_role(sk), sk);
	return ~0;
	}

	if (unlikely(interval == 0)) {
	DCCP_WARN("%s(%p), Could not find a win_count interval > 0."
	"Defaulting to 1\n", dccp_role(sk), sk);
	interval = 1;
	}
	found:
	if (!tail) {
	DCCP_CRIT("tail is null\n");
	return ~0;
	}

	delta = timeval_delta(&tstamp, &tail->dccphrx_tstamp);
	DCCP_BUG_ON(delta < 0);

	rtt = delta * 4 / interval;
	dccp_pr_debug("%s(%p), approximated RTT to %dus\n",
	dccp_role(sk), sk, (int)rtt);

	/*
	* Determine the length of the first loss interval via inverse lookup.
	* Assume that X_recv can be computed by the throughput equation
	* s
	* X_recv = --------
	* R * fval
	* Find some p such that f(p) = fval; return 1/p [RFC 3448, 6.3.1].
	*/
	if (rtt == 0) { /* would result in divide-by-zero */
	DCCP_WARN("RTT==0\n");
	return ~0;
	}

	dccp_timestamp(sk, &tstamp);
	delta = timeval_delta(&tstamp, last_feedback);
	DCCP_BUG_ON(delta <= 0);

	x_recv = scaled_div32(bytes_recv, delta);
	if (x_recv == 0) { /* would also trigger divide-by-zero */
	DCCP_WARN("X_recv==0\n");
	if (previous_x_recv == 0) {
	DCCP_BUG("stored value of X_recv is zero");
	return ~0;
	}
	x_recv = previous_x_recv;
	}

	fval = scaled_div(s, rtt);
	fval = scaled_div32(fval, x_recv);
	p = tfrc_calc_x_reverse_lookup(fval);

	dccp_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
	"loss rate=%u\n", dccp_role(sk), sk, x_recv, p);

	if (p == 0)
	return ~0;
	else
	return 1000000 / p;
	}

	void dccp_li_update_li(struct sock *sk,
	struct list_head *li_hist_list,
	struct list_head *hist_list,
	struct timeval *last_feedback, u16 s, u32 bytes_recv,
	u32 previous_x_recv, u64 seq_loss, u8 win_loss)
	{
	struct dccp_li_hist_entry *head;
	u64 seq_temp;

	if (list_empty(li_hist_list)) {
	if (!dccp_li_hist_interval_new(li_hist_list, seq_loss,
	win_loss))
	return;

	head = list_entry(li_hist_list->next, struct dccp_li_hist_entry,
	dccplih_node);
	head->dccplih_interval = dccp_li_calc_first_li(sk, hist_list,
	last_feedback,
	s, bytes_recv,
	previous_x_recv);
	} else {
	struct dccp_li_hist_entry *entry;
	struct list_head *tail;

	head = list_entry(li_hist_list->next, struct dccp_li_hist_entry,
	dccplih_node);
	/* FIXME win count check removed as was wrong */
	/* should make this check with receive history */
	/* and compare there as per section 10.2 of RFC4342 */

	/* new loss event detected */
	/* calculate last interval length */
	seq_temp = dccp_delta_seqno(head->dccplih_seqno, seq_loss);
	entry = dccp_li_hist_entry_new(GFP_ATOMIC);

	if (entry == NULL) {
	DCCP_BUG("out of memory - can not allocate entry");
	return;
	}

	list_add(&entry->dccplih_node, li_hist_list);

	tail = li_hist_list->prev;
	list_del(tail);
	kmem_cache_free(dccp_li_cachep, tail);

	/* Create the newest interval */
	entry->dccplih_seqno = seq_loss;
	entry->dccplih_interval = seq_temp;
	entry->dccplih_win_count = win_loss;
	}
	}

	EXPORT_SYMBOL_GPL(dccp_li_update_li);

	static __init int dccp_li_init(void)
	{
	dccp_li_cachep = kmem_cache_create("dccp_li_hist",
	sizeof(struct dccp_li_hist_entry),
	0, SLAB_HWCACHE_ALIGN, NULL);
	return dccp_li_cachep == NULL ? -ENOBUFS : 0;
	}

	static __exit void dccp_li_exit(void)
	{
	kmem_cache_destroy(dccp_li_cachep);
	}

	module_init(dccp_li_init);
	module_exit(dccp_li_exit);