[asterisk-dev] RTP Bridging optimization

[Vadim Lebedev]

Kevin P. Fleming wrote:

>Vadim Lebedev wrote:
>
>  
>
>>The trick is that the pipe is ALWAYS empty.... And when we push
>>something to the pipe, we pull the data from it immideately afterwards.
>>    
>>
>
>So you've replaced a pair of read()/write() calls with two calls to
>splice()? It's the same number of userspace/kernelspace boundary
>crossings, I can't see how this would be any significant improvement at all.
>
>  
>
Kewin,

Now, when we agree that it IS possible  to use single pipe for multiple 
bridges
let's look on benefits:

As for now Asterisk when packet arrives on a briged socket
    1. Thread switch to the reader thread
    2. read from socket + transfer of data from kernel to user
    3. thread swicth to writer thread
    4. write to socket +  transfer of data from user to kernel

Now if my proposal is implemented in the worst case we will economise 2 
thread switches, 2 user/kernel data transfers
plus we'll have much less threads in the system.

I think we can expect pretty dramatic improvements

Thanks
Vadim


>The whole point of splice() and tee() are to allow *streams* of data to
>be copied without having to bring the data from kernelspace to
>userspace; doing it one packet at a time will probably defeat the
>purpose of using them entirely.
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