Re: [PATCH] mm: Implement Swap Prefetching v23

[Con Kolivas <kernel@kolivas.org>]

On Friday 10 February 2006 16:01, Nick Piggin wrote:
> Andrew Morton wrote:
> > Nick Piggin <nickpiggin@yahoo.com.au> wrote:
> >>Andrew Morton wrote:
> >>>Con Kolivas <kernel@kolivas.org> wrote:
> >>>>Ok I see. We don't have a way to add to the tail of that list though?
> >>>
> >>>del_page_from_lru() + (new) add_page_to_inactive_list_tail().
> >>>
> >>>>Is that
> >>>>a worthwhile addition to this (ever growing) project? That would
> >>>> definitely have an impact on the other code if not all done within
> >>>> swap_prefetch.c.. which would also be quite a large open coded
> >>>> something.
> >>>
> >>>Do both of the above in a new function in swap.c.
> >>
> >>That'll require the caller to do lru locking.
> >>
> >>I'd add an lru_cache_add_tail, use it instead of the current
> >> lru_cache_add that Con's got now, and just implement it in a simple
> >> manner, without pagevecs.
> >
> > umm, that's what I said ;)
>
> You said del_page_from_lru(), which doesn't belong in a function
> called lru_cache_add_tail.

Just so it's clear I understand, is this what you (both) had in mind?
Inline so it's not built for !CONFIG_SWAP_PREFETCH

Cheers,
Con
---
Index: linux-2.6.16-rc2-ck1/include/linux/mm_inline.h
===================================================================
--- linux-2.6.16-rc2-ck1.orig/include/linux/mm_inline.h	2006-02-04 09:55:14.000000000 +1100
+++ linux-2.6.16-rc2-ck1/include/linux/mm_inline.h	2006-02-10 16:21:20.000000000 +1100
@@ -14,6 +14,13 @@ add_page_to_inactive_list(struct zone *z
 }
 
 static inline void
+add_page_to_inactive_list_tail(struct zone *zone, struct page *page)
+{
+	list_add_tail(&page->lru, &zone->inactive_list);
+	zone->nr_inactive++;
+}
+
+static inline void
 del_page_from_active_list(struct zone *zone, struct page *page)
 {
 	list_del(&page->lru);
Index: linux-2.6.16-rc2-ck1/include/linux/swap.h
===================================================================
--- linux-2.6.16-rc2-ck1.orig/include/linux/swap.h	2006-02-10 16:16:05.000000000 +1100
+++ linux-2.6.16-rc2-ck1/include/linux/swap.h	2006-02-10 16:16:16.000000000 +1100
@@ -216,6 +216,9 @@ extern int shmem_unuse(swp_entry_t entry
 extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 
 #ifdef CONFIG_SWAP_PREFETCH
+/* mm/swap.c */
+extern void lru_cache_add_tail(struct page *page);
+
 /*	mm/swap_prefetch.c */
 extern int swap_prefetch;
 struct swapped_entry {
Index: linux-2.6.16-rc2-ck1/mm/swap.c
===================================================================
--- linux-2.6.16-rc2-ck1.orig/mm/swap.c	2006-02-09 21:53:37.000000000 +1100
+++ linux-2.6.16-rc2-ck1/mm/swap.c	2006-02-10 16:22:45.000000000 +1100
@@ -156,6 +156,13 @@ void fastcall lru_cache_add_active(struc
 	put_cpu_var(lru_add_active_pvecs);
 }
 
+inline void lru_cache_add_tail(struct page *page)
+{
+	struct zone *zone = page_zone(page);
+
+	add_page_to_inactive_list_tail(zone, page);
+}
+
 static void __lru_add_drain(int cpu)
 {
 	struct pagevec *pvec = &per_cpu(lru_add_pvecs, cpu);
Index: linux-2.6.16-rc2-ck1/mm/swap_prefetch.c
===================================================================
--- linux-2.6.16-rc2-ck1.orig/mm/swap_prefetch.c	2006-02-10 12:14:25.000000000 +1100
+++ linux-2.6.16-rc2-ck1/mm/swap_prefetch.c	2006-02-10 16:11:45.000000000 +1100
@@ -196,7 +196,7 @@ static enum trickle_return trickle_swap_
 		goto out_release;
 	}
 
-	lru_cache_add(page);
+	lru_cache_add_tail(page);
 	if (unlikely(swap_readpage(NULL, page))) {
 		ret = TRICKLE_DELAY;
 		goto out_release;