Re: [Ksummit-2009-discuss] Representing Embedded Architectures at the Kernel Summit

[Mike Frysinger <vapier.adi@gmail.com>]

On Wed, Jun 3, 2009 at 23:11, David VomLehn (dvomlehn) wrote:
> David Delaney has a proof-of-concept of an idea of his which was
> presented at the last CELF, which is basically to put the kernel and
> loadable kernel modules closely enough together that you can avoid the
> use of long jumps. He sees a better than 1% improvement in performance,
> which we've duplicated using a slightly different approach. This is nice
> payback for little work and, though it doesn't help on all processors,
> it helps on several.

it would help on the Blackfin architecture.  we compile all kernel
modules with -mlong-call because of this issue.

> The problem is: how do you allocate memory with the magical "close to
> the kernel" attribute? We have something that adds a new ZONE_KERNEL
> (this name has some problems, actually). It seems like a pretty good
> solution if you look at zones as conceptually concentric usages, but
> with the current zone implementation, each zone must be contiguous. So,
> if we're talking about changing what zones are done, I'd like to throw
> this into the pot.

what do you do if the alloc fails ?  return back to userspace with
something like ENOMEM and have it retry with a module that was
compiled with -mlong-call ?
-mike