On Tue, Oct 26, 2010 at 6:08 PM, KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> > > Add an function to allocate contiguous memory larger than MAX_ORDER. > The main difference between usual page allocator is that this uses > memory offline technique (Isolate pages and migrate remaining pages.). > > I think this is not 100% solution because we can't avoid fragmentation, > but we have kernelcore= boot option and can create MOVABLE zone. That > helps us to allow allocate a contiguous range on demand. > > The new function is > > Âalloc_contig_pages(base, end, nr_pages, alignment) > > This function will allocate contiguous pages of nr_pages from the range > [base, end). If [base, end) is bigger than nr_pages, some pfn which > meats alignment will be allocated. If alignment is smaller than MAX_ORDER, > it will be raised to be MAX_ORDER. > > __alloc_contig_pages() has much more arguments. > > Some drivers allocates contig pages by bootmem or hiding some memory > from the kernel at boot. But if contig pages are necessary only in some > situation, kernelcore= boot option and using page migration is a choice