linux_dsm_epyc7002/net/dccp/ccids/lib/tfrc.h
Gerrit Renker 8a9c7e92e0 [TFRC]: Ringbuffer to track loss interval history
A ringbuffer-based implementation of loss interval history is easier to
maintain, allocate, and update.

The `swap' routine to keep the RX history sorted is due to and was written
by Arnaldo Carvalho de Melo, simplifying an earlier macro-based variant.

Details:
 * access to the Loss Interval Records via macro wrappers (with safety checks);
 * simplified, on-demand allocation of entries (no extra memory consumption on
   lossless links); cache allocation is local to the module / exported as service;
 * provision of RFC-compliant algorithm to re-compute average loss interval;
 * provision of comprehensive, new loss detection algorithm
 	- support for all cases of loss, including re-ordered/duplicate packets;
 	- waiting for NDUPACK=3 packets to fill the hole;
	- updating loss records when a late-arriving packet fills a hole.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 14:57:18 -08:00

65 lines
1.8 KiB
C

#ifndef _TFRC_H_
#define _TFRC_H_
/*
* net/dccp/ccids/lib/tfrc.h
*
* Copyright (c) 2007 The University of Aberdeen, Scotland, UK
* Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
* Copyright (c) 2005-6 Ian McDonald <ian.mcdonald@jandi.co.nz>
* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
* Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
*
* 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/types.h>
#include <asm/div64.h>
#include "../../dccp.h"
/* internal includes that this module exports: */
#include "loss_interval.h"
#include "packet_history.h"
#ifdef CONFIG_IP_DCCP_TFRC_DEBUG
extern int tfrc_debug;
#define tfrc_pr_debug(format, a...) DCCP_PR_DEBUG(tfrc_debug, format, ##a)
#else
#define tfrc_pr_debug(format, a...)
#endif
/* integer-arithmetic divisions of type (a * 1000000)/b */
static inline u64 scaled_div(u64 a, u32 b)
{
BUG_ON(b==0);
a *= 1000000;
do_div(a, b);
return a;
}
static inline u32 scaled_div32(u64 a, u32 b)
{
u64 result = scaled_div(a, b);
if (result > UINT_MAX) {
DCCP_CRIT("Overflow: a(%llu)/b(%u) > ~0U",
(unsigned long long)a, b);
return UINT_MAX;
}
return result;
}
/**
* tfrc_ewma - Exponentially weighted moving average
* @weight: Weight to be used as damping factor, in units of 1/10
*/
static inline u32 tfrc_ewma(const u32 avg, const u32 newval, const u8 weight)
{
return avg ? (weight * avg + (10 - weight) * newval) / 10 : newval;
}
extern u32 tfrc_calc_x(u16 s, u32 R, u32 p);
extern u32 tfrc_calc_x_reverse_lookup(u32 fvalue);
#endif /* _TFRC_H_ */