535c55df13
This adds a function to take care of the following cases occurring in the
computation of the Loss Rate p:
* 1/(2^32-1) is mapped into 0% as per RFC 4342, 8.5;
* 1/0 is mapped into the maximum of 100%;
* we want to avoid that p = 1/x is rounded down to 0 when x is very large,
since this means accidentally re-entering slow-start (indicated by p==0).
In the last case, the minimum-resolution value of p is returned.
Furthermore, a bug in ccid3_hc_rx_getsockopt is fixed (1/0 was mapped into ~0U),
which now allows to consistently print the scaled p-values as
printf("Loss Event Rate = %u.%04u %%\n", rx_info.tfrcrx_p / 10000,
rx_info.tfrcrx_p % 10000);
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
70 lines
2.1 KiB
C
70 lines
2.1 KiB
C
#ifndef _TFRC_H_
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#define _TFRC_H_
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/*
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* net/dccp/ccids/lib/tfrc.h
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*
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* Copyright (c) 2007 The University of Aberdeen, Scotland, UK
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* Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
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* Copyright (c) 2005-6 Ian McDonald <ian.mcdonald@jandi.co.nz>
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* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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* Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/types.h>
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#include <linux/math64.h>
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#include "../../dccp.h"
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/* internal includes that this module exports: */
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#include "loss_interval.h"
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#include "packet_history.h"
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#ifdef CONFIG_IP_DCCP_TFRC_DEBUG
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extern int tfrc_debug;
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#define tfrc_pr_debug(format, a...) DCCP_PR_DEBUG(tfrc_debug, format, ##a)
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#else
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#define tfrc_pr_debug(format, a...)
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#endif
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/* integer-arithmetic divisions of type (a * 1000000)/b */
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static inline u64 scaled_div(u64 a, u64 b)
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{
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BUG_ON(b==0);
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return div64_u64(a * 1000000, b);
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}
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static inline u32 scaled_div32(u64 a, u64 b)
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{
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u64 result = scaled_div(a, b);
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if (result > UINT_MAX) {
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DCCP_CRIT("Overflow: %llu/%llu > UINT_MAX",
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(unsigned long long)a, (unsigned long long)b);
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return UINT_MAX;
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}
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return result;
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}
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/**
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* tfrc_ewma - Exponentially weighted moving average
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* @weight: Weight to be used as damping factor, in units of 1/10
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*/
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static inline u32 tfrc_ewma(const u32 avg, const u32 newval, const u8 weight)
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{
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return avg ? (weight * avg + (10 - weight) * newval) / 10 : newval;
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}
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extern u32 tfrc_calc_x(u16 s, u32 R, u32 p);
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extern u32 tfrc_calc_x_reverse_lookup(u32 fvalue);
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extern u32 tfrc_invert_loss_event_rate(u32 loss_event_rate);
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extern int tfrc_tx_packet_history_init(void);
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extern void tfrc_tx_packet_history_exit(void);
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extern int tfrc_rx_packet_history_init(void);
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extern void tfrc_rx_packet_history_exit(void);
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extern int tfrc_li_init(void);
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extern void tfrc_li_exit(void);
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#endif /* _TFRC_H_ */
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