Re: Large slab cache in 2.6.1

[Nick Piggin]

Mike Fedyk wrote:

> Nick Piggin wrote:
>
> > Nick Piggin wrote:
> >
> > > Actually I think the previous shrink_slab formula factors
> > > out to the right thing anyway, so nevermind this patch :P
> >
> > Although, nr_used_zone_pages probably shouldn't be counting
> > highmem zones, which might be our problem.
>
>
> What is the kernel parameter to disable highmem?  I saw nohighio, but 
> that's not it...

Not sure. That defeats the purpose of trying to get your setup
working nicely though ;)

Can you upgrade to 2.6.3-mm2? It would be ideal if you could
test this patch against that kernel due to the other VM changes.

Chris, could you test this too please? Thanks.

 linux-2.6-npiggin/include/linux/mm.h |    2 +-
 linux-2.6-npiggin/mm/page_alloc.c    |   13 +++++++++----
 linux-2.6-npiggin/mm/vmscan.c        |   22 ++++++++++++----------
 3 files changed, 22 insertions(+), 15 deletions(-)

diff -puN mm/vmscan.c~vm-shrink-slab-lowmem mm/vmscan.c
--- linux-2.6/mm/vmscan.c~vm-shrink-slab-lowmem	2004-02-22 16:35:06.000000000 +1100
+++ linux-2.6-npiggin/mm/vmscan.c	2004-02-22 16:35:06.000000000 +1100
@@ -145,7 +145,7 @@ static int shrink_slab(unsigned long sca
 	if (down_trylock(&shrinker_sem))
 		return 0;
 
-	pages = nr_used_zone_pages();
+	pages = nr_lowmem_lru_pages();
 	list_for_each_entry(shrinker, &shrinker_list, list) {
 		unsigned long long delta;
 
@@ -857,7 +857,8 @@ shrink_zone(struct zone *zone, unsigned 
  */
 static int
 shrink_caches(struct zone **zones, int priority, int *total_scanned,
-		int gfp_mask, int nr_pages, struct page_state *ps)
+		int *lowmem_scanned, int gfp_mask, int nr_pages,
+		struct page_state *ps)
 {
 	int ret = 0;
 	int i;
@@ -875,7 +876,10 @@ shrink_caches(struct zone **zones, int p
 
 		ret += shrink_zone(zone, gfp_mask,
 				to_reclaim, &nr_scanned, ps, priority);
+
 		*total_scanned += nr_scanned;
+		if (i < ZONE_HIGHMEM)
+			*lowmem_scanned += nr_scanned;
 		if (ret >= nr_pages)
 			break;
 	}
@@ -915,19 +919,17 @@ int try_to_free_pages(struct zone **zone
 		zones[i]->temp_priority = DEF_PRIORITY;
 
 	for (priority = DEF_PRIORITY; priority >= 0; priority--) {
-		int total_scanned = 0;
+		int total_scanned = 0, lowmem_scanned = 0;
 		struct page_state ps;
 
 		get_page_state(&ps);
 		nr_reclaimed += shrink_caches(zones, priority, &total_scanned,
-						gfp_mask, nr_pages, &ps);
+				&lowmem_scanned, gfp_mask, nr_pages, &ps);
 
-		if (zones[0] - zones[0]->zone_pgdat->node_zones < ZONE_HIGHMEM) {
-			shrink_slab(total_scanned, gfp_mask);
-			if (reclaim_state) {
-				nr_reclaimed += reclaim_state->reclaimed_slab;
-				reclaim_state->reclaimed_slab = 0;
-			}
+		shrink_slab(lowmem_scanned, gfp_mask);
+		if (reclaim_state) {
+			nr_reclaimed += reclaim_state->reclaimed_slab;
+			reclaim_state->reclaimed_slab = 0;
 		}
 
 		if (nr_reclaimed >= nr_pages) {
diff -puN mm/page_alloc.c~vm-shrink-slab-lowmem mm/page_alloc.c
--- linux-2.6/mm/page_alloc.c~vm-shrink-slab-lowmem	2004-02-22 16:35:06.000000000 +1100
+++ linux-2.6-npiggin/mm/page_alloc.c	2004-02-22 16:35:06.000000000 +1100
@@ -772,13 +772,18 @@ unsigned int nr_free_pages(void)
 
 EXPORT_SYMBOL(nr_free_pages);
 
-unsigned int nr_used_zone_pages(void)
+unsigned int nr_lowmem_lru_pages(void)
 {
+	pg_data_t *pgdat;
 	unsigned int pages = 0;
-	struct zone *zone;
 
-	for_each_zone(zone)
-		pages += zone->nr_active + zone->nr_inactive;
+	for_each_pgdat(pgdat) {
+		int i;
+		for (i = 0; i < ZONE_HIGHMEM; i++) {
+			struct zone *zone = pgdat->node_zones + i;
+			pages += zone->nr_active + zone->nr_inactive;
+		}
+	}
 
 	return pages;
 }
diff -puN include/linux/mm.h~vm-shrink-slab-lowmem include/linux/mm.h
--- linux-2.6/include/linux/mm.h~vm-shrink-slab-lowmem	2004-02-22 16:35:06.000000000 +1100
+++ linux-2.6-npiggin/include/linux/mm.h	2004-02-22 16:35:06.000000000 +1100
@@ -625,7 +625,7 @@ static inline struct vm_area_struct * fi
 
 extern struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr);
 
-extern unsigned int nr_used_zone_pages(void);
+extern unsigned int nr_lowmem_lru_pages(void);
 
 extern struct page * vmalloc_to_page(void *addr);
 extern struct page * follow_page(struct mm_struct *mm, unsigned long address,

_