Re: [RFC] Avoiding fragmentation through different allocator

[William Lee Irwin III <wli@holomorphy.com>]

On Wed, Jan 12, 2005 at 09:09:24PM +0000, Mel Gorman wrote:
> So... What the patch does. Allocations are divided up into three different
> types of allocations;
> UserReclaimable - These are userspace pages that are easily reclaimable. Right
> 	now, I'm putting all allocations of GFP_USER and GFP_HIGHUSER as
> 	well as disk-buffer pages into this category. These pages are trivially
> 	reclaimed by writing the page out to swap or syncing with backing
> 	storage
> KernelReclaimable - These are pages allocated by the kernel that are easily
> 	reclaimed. This is stuff like inode caches, dcache, buffer_heads etc.
> 	These type of pages potentially could be reclaimed by dumping the
> 	caches and reaping the slabs (drastic, but you get the idea). We could
> 	also add pages into this category that are known to be only required
> 	for a short time like buffers used with DMA
> KernelNonReclaimable - These are pages that are allocated by the kernel that
> 	are not trivially reclaimed. For example, the memory allocated for a
> 	loaded module would be in this category. By default, allocations are
> 	considered to be of this type

I'd expect to do better with kernel/user discrimination only, having
address-ordering biases in opposite directions for each case.

-- wli