[gambit-list] newbie question: output from one port as input to another port

Marc Feeley feeley at iro.umontreal.ca
Sun Mar 12 15:08:08 EST 2006


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




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