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    <p>It seems like this could be most directly solved by calculating the throttle sleep time in the send thread. I'm not sure I see the benefit of another thread to do this work.</p> <p>Here is one way to do this:</p> <p>Select a time window in which you will measure your send rate. Based on your target bandwidth this will give you a byte maximum for that amount of time. You can then check to see if you have sent that many bytes after each sendto(). If you do exceed the byte threshold then sleep until the end of the window in order to perform the throttling.</p> <p>Here is some untested code showing the idea. Sorry that clock_gettime and struct timespec add some complexity. Google has some nice code snippets for doing more complete comparisons, addition, and subtraction with struct timespec.</p> <pre><code>#define MAX_BYTES_PER_SECOND (128L * 1024L) #define TIME_WINDOW_MS 50L #define MAX_BYTES_PER_WINDOW ((MAX_BYTES_PER_SECOND * TIME_WINDOW_MS) / 1000L) #include &lt;time.h&gt; #include &lt;stdlib.h&gt; int foo(void) { struct timespec window_start_time; size_t bytes_sent_in_window = 0; clock_gettime(CLOCK_REALTIME, &amp;window_start_time); while (1) { size_t bytes_sent = sendto(sock, buff, strlen(buff), 0, (struct sockaddr *) &amp;sin, sizeof(sin)); if (bytes_sent &lt; 0) { // error handling } else { bytes_sent_in_window += bytes_sent; if (bytes_sent_in_window &gt;= MAX_BYTES_PER_WINDOW) { struct timespec now; struct timespec thresh; // Calculate the end of the window thresh.tv_sec = window_start_time.tv_sec; thresh.tv_nsec = window_start_time.tv_nsec; thresh.tv_nsec += TIME_WINDOW_MS * 1000000; if (thresh.tv_nsec &gt; 1000000000L) { thresh.tv_sec += 1; thresh.tv_nsec -= 1000000000L; } // get the current time clock_gettime(CLOCK_REALTIME, &amp;now); // if we have not gotten to the end of the window yet if (now.tv_sec &lt; thresh.tv_sec || (now.tv_sec == thresh.tv_sec &amp;&amp; now.tv_nsec &lt; thresh.tv_nsec)) { struct timespec remaining; // calculate the time remaining in the window // - See google for more complete timespec subtract algorithm remaining.tv_sec = thresh.tv_sec - now.tv_sec; if (thresh.tv_nsec &gt;= now.tv_nsec) { remaining.tv_nsec = thresh.tv_nsec - now.tv_nsec; } else { remaining.tv_nsec = 1000000000L + thresh.tv_nsec - now.tv_nsec; remaining.tv_sec -= 1; } // Sleep to end of window nanosleep(&amp;remaining, NULL); } // Reset counters and timestamp for next window bytes_sent_in_window = 0; clock_gettime(CLOCK_REALTIME, &amp;window_start_time); } } } } </code></pre>
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    1. POC Linux Bandwidth Throttling of Application
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    1. USBen Kelly
    1. USBen Kelly
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    1. COsilly question on my behalf but what would i need to change to make it throttle based on how much % of the total bandwidth i want to use? id assume the TIME_WINDOW_MS is the variable but i dont quite get how i can modify it to do what i need. also is the -lrt linker library standard to most linux machines? if not would i be able to use `struct timeval` instead?
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      1. USrandy newfield
    2. COthanks allot. this method is actually throttling the bandwidth back. i just do not know how to convert TIME_WINDOW_MS into a time which resembles a percentage of the total allowed bandwidth.
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      1. USrandy newfield
    3. COi cant edit my last two comments but ive tried editing MAX_BYTES_PER_SECOND to equate to a throttled back bandwidth speed `mbps = ((60 * 10) / 100) * 1024` which should equate to 6kb/s or 6144 bytes, but it doesnt seem to throttle the connection back at all. what does seem to throttle the connection though is modifying the TIME_WINDOW_MS value and increasing it up somewhere to 1 second (1000000). do i have to create some sort if gain for the TIME_WINDOW_MS variable to increase it until bytes being sent equals my estimated throttled bandwidth or should modifying max bytes per window be enough?
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