Re: [RFC][PATCH] Sparse Memory Handling (hot-add foundation)

Dave Hansen
2005-02-18T15:42:34Z

On Fri, 2005-02-18 at 11:04 +0100, Andi Kleen wrote:
> Dave Hansen <haveblue@us.ibm.com> writes:
>
> > The attached patch, largely written by Andy Whitcroft, implements a
> > feature which is similar to DISCONTIGMEM, but has some added features.
> > Instead of splitting up the mem_map for each NUMA node, this splits it
> > up into areas that represent fixed blocks of memory. This allows
> > individual pieces of that memory to be easily added and removed.
>
> I'm curious - how does this affect .text size for a i386 or x86-64 NUMA
> kernel? One area I wanted to improve on x86-64 for a long time was
> to shrink the big virt_to_page() etc. inline macros. Your new code
> actually looks a bit smaller.

On x86, it looks like a 3k increase in text size. I know Matt Tolentino
has been testing it on x86_64, he might have a comparison there for you.

$ size i386-T41-laptop*/vmlinux
text data bss dec hex filename
2897131 580592 204252 3681975 382eb7 i386-T41-laptop.sparse/vmlinux
2894166 581832 203228 3679226 3823fa i386-T41-laptop/vmlinux

BTW, this PAE is on and uses 36-bits of physaddr space.