Re: Proposal: merged system calls

Alan Cox (alan@lxorguk.ukuu.org.uk)
Mon, 20 May 1996 18:23:06 +0100 (BST)


> But Alan Cox's comments pointed out that the major advantage - avoiding
> copying between user space and kernel space - doesnt really exist, the
> viability of such an interface is questionable :) :(

It has some advantages for very fast message passing. I think however stuff
like U-Net addresses this better by doing userspace ultrafast networking linked
to the application with no demux overheads and the like.

What I'd like to see however is optimising the return path from a syscall. Im
convinced that we could have a "fast return path", and make need_resched, and
signal delivery overwrite the return address on the stack to a slow return
and that it would be a measurable win - Linus, we need to get syscalls down
to 2uS not 3 ;)

Alan