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POC++ socket programming: maximize throughput/bandwidth on localhost (I only get 3 Gbit/s instead of 23GBit/s)
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  1. POC++ socket programming: maximize throughput/bandwidth on localhost (I only get 3 Gbit/s instead of 23GBit/s)
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    copied!<p>I want to create a C++ server/client that maximizes the throughput over TCP socket communication on my localhost. As a preparation, I used <a href="http://sourceforge.net/projects/iperf/" rel="nofollow">iperf</a> to find out what the maximum bandwidth is on my i7 MacBookPro.</p> <pre><code>------------------------------------------------------------ Server listening on TCP port 5001 TCP window size: 256 KByte (default) ------------------------------------------------------------ [ 4] local 127.0.0.1 port 5001 connected with 127.0.0.1 port 51583 [ 4] 0.0-120.0 sec 329 GBytes 23.6 Gbits/sec </code></pre> <p>Without any tweaking, ipref showed me that I can reach at least 23.2 GBit/s. Then I did my own C++ server/client implementation, you can find the full code here: <a href="https://gist.github.com/1116635" rel="nofollow">https://gist.github.com/1116635</a></p> <p>I that code I basically transfer a 1024bytes int array with each read/write operation. So my send loop on the server looks like this:</p> <pre><code> int n; int x[256]; //fill int array for (int i=0;i&lt;256;i++) { x[i]=i; } for (int i=0;i&lt;(4*1024*1024);i++) { n = write(sock,x,sizeof(x)); if (n &lt; 0) error("ERROR writing to socket"); } </code></pre> <p>My receive loop on the client looks like this:</p> <pre><code>int x[256]; for (int i=0;i&lt;(4*1024*1024);i++) { n = read(sockfd,x,((sizeof(int)*256))); if (n &lt; 0) error("ERROR reading from socket"); } </code></pre> <p>As mention in the headline, running this (compiled with -O3) results in the following execution time which is about 3 GBit/s:</p> <pre><code>./client 127.0.0.1 1234 Elapsed time for Reading 4GigaBytes of data over socket on localhost: 9578ms </code></pre> <p>Where do I loose the bandwidth, what am I doing wrong? Again, the full code can be seen here: <a href="https://gist.github.com/1116635" rel="nofollow">https://gist.github.com/1116635</a></p> <p>Any help is appreciated!</p>
 

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