Messages in this thread | | | Subject | Re: [RFC] Tight check of pfn_valid on sparsemem | From | Dave Hansen <> | Date | Tue, 13 Jul 2010 09:35:33 -0700 |
| |
On Wed, 2010-07-14 at 00:43 +0900, Minchan Kim wrote: > 3 is not a big deal than 2 about memory usage. > If the system use memory space fully(MAX_PHYSMEM_BITS 31), it just consumes > 1024(128 * 8) byte. So now I think best solution is 2. > > Russell. What do you think about it?
I'm not Russell, but I'll tell you what I think. :)
Make the sections 16MB. You suggestion to add the start/end pfns _doubles_ the size of the structure, and its size overhead. We have systems with a pretty tremendous amount of memory with 16MB sections.
If you _really_ can't make the section size smaller, and the vast majority of the sections are fully populated, you could hack something in. We could, for instance, have a global list that's mostly readonly which tells you which sections need to be have their sizes closely inspected. That would work OK if, for instance, you only needed to check a couple of memory sections in the system. It'll start to suck if you made the lists very long.
-- Dave
| |