Date: Fri, 29 Oct 2004 13:45:15 -0700 From: Julian Elischer <julian@elischer.org> To: Ollie Cook <ollie@uk.clara.net> Cc: freebsd-net@freebsd.org Subject: Re: Efficient copying between sockets Message-ID: <4182ABDB.7040104@elischer.org> In-Reply-To: <20041029123506.GG19662@mutare.noc.clara.net> References: <20041029123506.GG19662@mutare.noc.clara.net>
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Ollie Cook wrote: >Good afternoon, > >I am currently writing a potentially high bandwidth (think fileserver) >application which will proxy data from one PF_INET socket to another (no reason >it has to be PF_INET, but that's how the application stands). > >At the moment this is implemented as follows (in pseudo-C; no error-checking >for brevity and clarity): > > written_bytes = 0; > read_bytes = read(sock_src, buffer, sz_buffer); > while (written_bytes < read_bytes) > written_bytes -= write(sock_dst, buffer, read_bytes - written_bytes) > >I am wondering if there is a more efficient approach to this which might avoid >copying data into a userspace buffer, and then writing it back to the kernel? > you can do it entirely in the kernel if you write a program to configure two netgraph ksockets to each other > >In actual fact, I know in advance exactly how many bytes need to be copied from >one socket to the other, so if there was any way of doing something like: > > socket_redirect(sock_src, sock_dst, bytes_to_copy); > >it would be ideal. However I'd be very surprised if such a trivial way to do >that did actually exist. > >If anyone has any advice at all on a more efficient way to copy data between >sockets I'd be very glad to hear about it. The software is very much prototype >at the moment, but I'd like to make it as efficient as possible from the >beginning and this seems like a prime area for optimisation. > >Yours, > >Ollie > > >
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