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