On 12-Mar-06, at 2:22 PM, Samuel Montgomery-Blinn wrote:

Doesn't this waste time not reading the input port while writing to the output port if the input port could be read while the output port is being written, and similarly waste time not writing to the output port while reading from the input port?

-Sam

If you have a single CPU, it will either be filling the buffer (reading) or draining the buffer (writing). So it can't really do both at the same time. However, your disk, network card, and CPU can all be working in parallel because the network card and disk have internal buffers (i.e. when the write-subu8vector returns, the network card (and TCP stack) will still be actively sending packets out, which leaves enough time for the next disk access to occur). Of course YMMV depending on the speed of the CPU, network card and disk. Just measure how close you can get to the bandwidth of your network. I'm confident you will be pretty close.

Marc