CPU, PCI, PCIe, USB, Gigabit Ethernet, DMA/XOR engines, etc. | 2621400 | 2621400 | 33.0 | somewhat the theory value | The length of the auxilliary data buffer may be dependent on the key + The length of. The following table summarizes the results: | send buf size | recv buf size | throughput | comment | Then I tried several combinations of send/recv buffer sizes for a single pair of server and client. Why do I need more than one process to use up the bandwidth? FWIW, below is part of /proc/net/bonding/bond0: Bonding Mode: IEEE 802.3ad Dynamic link aggregation Then I tried two servers and two clients, this time the throughput moved up to about 225 MB/s, much nearer to the ideal maximum throughput. Checking with ifconfig, I saw that most packets went through a single interface between eth0 and eth1. A single pair of server and client made use of only one eithernet controller in this case. The actual throughput in this setting was about 117 MB/s. The purpose of this case is to establish a baseline of other experiments. I did not set the size of either the send buffer or the receive buffer, letting the kernel autotune them. In the first run, I ran one instance of server and one instance of client. The maximum throughput is 256 MB/s, and a proper setting of send/recv buffer sizes should be about 256 MB/s * 0.09 s ~ 2415919 bytes. Both nodes are installed two Gigabit ethernet controllers. The programs run on two nodes from two different datacenters, the ping response time between them is about 9 msecs. While sending data, the client uses send with the full size of the mmapped buffer as the initial argument. The received data is copied into an application buffer using recv and then dropped. The server simply listens on a port, waiting for the client to send data from an mmaped file. The test programs include a server and a client. I am experimenting with TCP buffer size tuning on Linux, but various results make me confused. (This question was originally posted on stack overflow Andy told me that I could get faster help here, so it is re-posted here now.)
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