ksm: singly-linked rmap_list
authorHugh Dickins <hugh.dickins@tiscali.co.uk>
Tue, 15 Dec 2009 01:59:19 +0000 (17:59 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 15 Dec 2009 16:53:19 +0000 (08:53 -0800)
commit6514d511dbe5a77b4bdc0a7e26fd679585112e1e
treea3fcf75191b7900043172d147fc7ed8ea97f3b4a
parent8dd3557a52f0bc8c960307721da307370ccad6fd
ksm: singly-linked rmap_list

Free up a pointer in struct rmap_item, by making the mm_slot's rmap_list a
singly-linked list: we always traverse that list sequentially, and we
don't even lose any prefetches (but should consider adding a few later).
Name it rmap_list throughout.

Do we need to free up that pointer?  Not immediately, and in the end, we
could continue to avoid it with a union; but having done the conversion,
let's keep it this way, since there's no downside, and maybe we'll want
more in future (struct rmap_item is a cache-friendly 32 bytes on 32-bit
and 64 bytes on 64-bit, so we shall want to avoid expanding it).

Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/ksm.c