diff -Nurp --exclude-from=/home/mcd/.dontdiff linux-2.6.0-test9-bk23/include/linux/mm.h linux-2.6.0-test9-nodezone_shift/include/linux/mm.h
--- linux-2.6.0-test9-bk23/include/linux/mm.h Sat Oct 25 11:42:50 2003
+++ linux-2.6.0-test9-nodezone_shift/include/linux/mm.h Tue Nov 18 13:46:47 2003
@@ -323,20 +323,31 @@ static inline void put_page(struct page
* The zone field is never updated after free_area_init_core()
* sets it, so none of the operations on it need to be atomic.
*/
-#define ZONE_SHIFT (BITS_PER_LONG - 8)
+#define NODEZONE_SHIFT (BITS_PER_LONG - MAX_NODES_SHIFT - MAX_ZONES_SHIFT)
+#define NODEZONE(node, zone) ((node << ZONES_SHIFT) | zone)
+
+static inline unsigned long page_zonenum(struct page *page)
+{
+ return (page->flags >> NODEZONE_SHIFT) & (~(~0UL << ZONES_SHIFT));
+}
+
+static inline unsigned long page_nodenum(struct page *page)
+{
+ return (page->flags >> NODEZONE_SHIFT + ZONES_SHIFT);
+}
struct zone;
extern struct zone *zone_table[];
static inline struct zone *page_zone(struct page *page)
{
- return zone_table[page->flags >> ZONE_SHIFT];
+ return zone_table[page->flags >> NODEZONE_SHIFT];
}
-static inline void set_page_zone(struct page *page, unsigned long zone_num)
+static inline void set_page_zone(struct page *page, unsigned long nodezone_num)
{
- page->flags &= ~(~0UL << ZONE_SHIFT);
- page->flags |= zone_num << ZONE_SHIFT;
+ page->flags &= ~(~0UL << NODEZONE_SHIFT);
+ page->flags |= nodezone_num << NODEZONE_SHIFT;
}
#ifndef CONFIG_DISCONTIGMEM
diff -Nurp --exclude-from=/home/mcd/.dontdiff linux-2.6.0-test9-bk23/include/linux/mmzone.h linux-2.6.0-test9-nodezone_shift/include/linux/mmzone.h
--- linux-2.6.0-test9-bk23/include/linux/mmzone.h Sat Oct 25 11:43:49 2003
+++ linux-2.6.0-test9-nodezone_shift/include/linux/mmzone.h Tue Nov 18 14:34:34 2003
@@ -159,8 +159,10 @@ struct zone {
#define ZONE_DMA 0
#define ZONE_NORMAL 1
#define ZONE_HIGHMEM 2
-#define MAX_NR_ZONES 3
-#define GFP_ZONEMASK 0x03
+
+#define MAX_NR_ZONES 3 /* Sync this with ZONES_SHIFT */
+#define ZONES_SHIFT 2 /* = ceil(log2(MAX_NR_ZONES)) */
+#define GFP_ZONEMASK 0x03
/*
* One allocation request operates on a zonelist. A zonelist
@@ -310,7 +312,7 @@ extern struct pglist_data contig_page_da
#if BITS_PER_LONG == 32
/*
- * with 32 bit flags field, page->zone is currently 8 bits.
+ * with 32 bit page->flags field, we reserve 8 bits for node/zone info.
* there are 3 zones (2 bits) and this leaves 8-2=6 bits for nodes.
*/
#define MAX_NODES_SHIFT 6
@@ -327,6 +329,13 @@ extern struct pglist_data contig_page_da
#error NODES_SHIFT > MAX_NODES_SHIFT
#endif
+/* There are currently 3 zones: DMA, Normal & Highmem, thus we need 2 bits */
+#define MAX_ZONES_SHIFT 2
+
+#if ZONES_SHIFT > MAX_ZONES_SHIFT
+#error ZONES_SHIFT > MAX_ZONES_SHIFT
+#endif
+
extern DECLARE_BITMAP(node_online_map, MAX_NUMNODES);
extern DECLARE_BITMAP(memblk_online_map, MAX_NR_MEMBLKS);
diff -Nurp --exclude-from=/home/mcd/.dontdiff linux-2.6.0-test9-bk23/mm/page_alloc.c linux-2.6.0-test9-nodezone_shift/mm/page_alloc.c
--- linux-2.6.0-test9-bk23/mm/page_alloc.c Sat Oct 25 11:42:53 2003
+++ linux-2.6.0-test9-nodezone_shift/mm/page_alloc.c Tue Nov 18 13:48:05 2003
@@ -50,7 +50,7 @@ EXPORT_SYMBOL(nr_swap_pages);
* Used by page_zone() to look up the address of the struct zone whose
* id is encoded in the upper bits of page->flags
*/
-struct zone *zone_table[MAX_NR_ZONES*MAX_NUMNODES];
+struct zone *zone_table[1 << (ZONES_SHIFT + NODES_SHIFT)];
EXPORT_SYMBOL(zone_table);
static char *zone_names[MAX_NR_ZONES] = { "DMA", "Normal", "HighMem" };
@@ -1210,7 +1210,7 @@ void __init memmap_init_zone(struct page
struct page *page;
for (page = start; page < (start + size); page++) {
- set_page_zone(page, nid * MAX_NR_ZONES + zone);
+ set_page_zone(page, NODEZONE(nid, zone));
set_page_count(page, 0);
SetPageReserved(page);
INIT_LIST_HEAD(&page->list);
@@ -1251,7 +1251,7 @@ static void __init free_area_init_core(s
unsigned long size, realsize;
unsigned long batch;
- zone_table[nid * MAX_NR_ZONES + j] = zone;
+ zone_table[NODEZONE(nid, j)] = zone;
realsize = size = zones_size[j];
if (zholes_size)
realsize -= zholes_size[j];
Matthew Dobson <[email protected]> wrote:
>
> Currently we keep track of a pages node & zone in the top 8 bits (on
> 32-bit arches, 10 bits on 64-bit arches) of page->flags. We typically
> do: node_num * MAX_NR_ZONES + zone_num = 'nodezone'. It's non-trivial
> to break this 'nodezone' back into node and zone numbers. This patch
> modifies the way we compute the index to be: (node_num << ZONE_SHIFT) |
> zone_num. This makes it trivial to recover either the node or zone
> number with a simple bitshift. There are many places in the kernel
> where we do things like: page_zone(page)->zone_pgdat->node_id to
> determine the node a page belongs to. With this patch we save several
> pointer dereferences, and it boils down to shifting some bits.
This rather conflicts with the patch from Jesse which I have. Can you guys
work that out and let me know when you're done?
On Sun, Nov 23, 2003 at 02:40:52PM -0800, Andrew Morton wrote:
> > zone_num. This makes it trivial to recover either the node or zone
> > number with a simple bitshift. There are many places in the kernel
> > where we do things like: page_zone(page)->zone_pgdat->node_id to
> > determine the node a page belongs to. With this patch we save several
> > pointer dereferences, and it boils down to shifting some bits.
>
> This rather conflicts with the patch from Jesse which I have. Can you guys
> work that out and let me know when you're done?
I like Matt's patch, but haven't tested it yet. I'll try it out on
Monday.
Jesse
On Sun, Nov 23, 2003 at 02:49:03PM -0800, Jesse Barnes wrote:
> On Sun, Nov 23, 2003 at 02:40:52PM -0800, Andrew Morton wrote:
> > > zone_num. This makes it trivial to recover either the node or zone
> > > number with a simple bitshift. There are many places in the kernel
> > > where we do things like: page_zone(page)->zone_pgdat->node_id to
> > > determine the node a page belongs to. With this patch we save several
> > > pointer dereferences, and it boils down to shifting some bits.
> >
> > This rather conflicts with the patch from Jesse which I have. Can you guys
> > work that out and let me know when you're done?
>
> I like Matt's patch, but haven't tested it yet. I'll try it out on
> Monday.
Matt, this looks ok (at least it boots on my test system). I wasn't
able test it on a very large system though, but it looks functionally
identical to the patch in Andrew's tree. Btw, you probably want to put
() around NODEZONE_SHIFT + ZONES_SHIFT in page_nodenum() otherwise gcc
will complain loudly.
Jesse