3 /* amok_bandwidth - Bandwidth test facilities */
5 /* Copyright (c) 2003-2005 Martin Quinson. All rights reserved. */
7 /* This program is free software; you can redistribute it and/or modify it
8 * under the terms of the license (GNU LGPL) which comes with this package. */
10 #ifndef AMOK_BANDWIDTH_H
11 #define AMOK_BANDWIDTH_H
13 #include "amok/base.h"
18 /** \addtogroup AMOK_bw
19 * \brief Test the bandwidth between two nodes
21 * This module allows you to retrieve the bandwidth between to arbitrary hosts
22 * and saturating the links leading to them, provided that they run some GRAS
23 * process which initialized this module.
25 * \htmlonly <h3>Bandwidth measurement</h3>\endhtmlonly
27 * Retrieving the bandwidth is usually done by active measurment: one send
28 * a packet of known size, time how long it needs to go back and forth,
29 * and you get the bandwidth in Kb/s available on the wire.
31 * This is not as easy as it first seems to do so in GRAS. The first issue
32 * is that GRAS messages can get buffered, or the receiver cannot be
33 * waiting for the message when it arrives. This results in extra delays
34 * impacting the measurement quality. You thus have to setup a rendez-vous
35 * protocol. The second issue is that GRAS message do have an header, so
36 * figuring out their size is not trivial. Moreover, they get converted
37 * when the sender and receiver processor architecture are different,
38 * inducing extra delays. For this, GRAS provide the so-called measurement
39 * sockets. On them, you can send raw data which is not converted (see
40 * \ref GRAS_sock_meas).
42 * Solving all these problems is quite error prone and anoying, so we
43 * implemented this in the current module so that you don't have to do it
44 * yourself. The API is very simple. Use amok_bw_test() to get the BW
45 * between the local host and the specified peer, or amok_bw_request() to
46 * get the BW between two remote hosts. The elapsed time, as long as the
47 * achieved bandwidth is returned in the last arguments of the functions.
49 * All sizes are in bytes. The \a buf_size is the size of the buffer
50 * (this is a socket parameter set automatically). The \a exp_size is the
51 * amount of data to send during an experiment. \a msg_size is the size
52 * of each message sent. These values allow you to study phenomenon such
53 * as TCP slow start (which are not correctly modelized by \ref SURF_API,
54 * yet). They are mimicked from the NWS API, and default values could be
55 * buf_size=32k, msg_size=16k and exp_size=64k. That means that the
56 * socket will be prepared to accept 32k in its buffer and then four
57 * messages of 16k will be sent (so that the total amount of data equals
58 * 64k). Of course, you can use other values if you want to.
61 * <center><img align=center src="amok_bw_test.png" alt="amok bandwidth measurement protocol"><br>
62 * Fig 1: AMOK bandwidth measurement protocol.</center>
63 * <h3>Link saturation</h3>
66 * You sometimes want to try saturating some link during the network
67 * related experiments (at least, we did ;). This also can turn quite
68 * untrivial to do, unless you use this great module. You can either ask
69 * for the saturation between the current host and a distant one with
70 * amok_bw_saturate_begin() or between two distant hosts with
71 * amok_bw_saturate_start(). In any case, remember that gras actors
72 * (processes) are not interruptible. It means that an actor you
73 * instructed to participate to a link saturation experiment will not do
74 * anything else until it is to its end (either because the asked duration
75 * was done or because someone used amok_bw_saturate_stop() on the emitter
76 * end of the experiment).
78 * The following figure depicts the used protocol. Note that any
79 * handshaking messages internal messages are omitted for sake of
80 * simplicity. In this example, the experiment ends before the planned
81 * experiment duration is over because one host use the
82 * amok_bw_saturate_stop() function, but things are not really different
83 * if the experiment stops alone. Also, it is not mandatory that the host
84 * calling amok_bw_saturate_stop() is the same than the one which called
85 * amok_bw_saturate_start(), despite what is depicted here.
88 * <center><img align=center src="amok_bw_sat.png" alt="amok bandwidth saturation protocol"><br>
89 * Fig 2: AMOK link saturation protocol.</center>
95 void amok_bw_init(void);
96 void amok_bw_exit(void);
98 void amok_bw_test(gras_socket_t peer,
99 unsigned long int buf_size,unsigned long int exp_size,unsigned long int msg_size,
100 /*OUT*/ double *sec, double *bw);
102 void amok_bw_request(const char* from_name,unsigned int from_port,
103 const char* to_name,unsigned int to_port,
104 unsigned long int buf_size,unsigned long int exp_size,unsigned long int msg_size,
105 /*OUT*/ double *sec, double*bw);
107 double * amok_bw_matrix(xbt_dynar_t hosts, /* dynar of xbt_host_t */
108 int buf_size_bw, int exp_size_bw, int msg_size_bw);
110 /* ***************************************************************************
112 * ***************************************************************************/
115 void amok_bw_saturate_start(const char* from_name,unsigned int from_port,
116 const char* to_name,unsigned int to_port,
117 unsigned int msg_size, double duration);
119 void amok_bw_saturate_begin(const char* to_name,unsigned int to_port,
120 unsigned int msg_size, double duration,
121 /*out*/ double *elapsed, double *bw);
123 void amok_bw_saturate_stop(const char* from_name,unsigned int from_port,
124 /*out*/ double *time, double *bw);
128 #endif /* AMOK_BANDWIDTH_H */