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SubjectRe: percpu-2.5.63-bk5-1 (properly generated)
At some point in the past, I wrote:
>> make -j44 bzImage > /dev/null 304.02s user 122.14s system 1299% cpu 32.792 total
[...]

On Sun, Mar 02, 2003 at 12:46:00PM -0800, Martin J. Bligh wrote:
> How does that compare with and without your patch though?

There's a relatively large (12s/44s == 27%) difference between absolute
timings on our machines, which suggests a large disturbance in the force.
2.5.63-bk5 virgin appears to get timings in the low 40's.


On Sun, Mar 02, 2003 at 12:46:00PM -0800, Martin J. Bligh wrote:
> Would be useful if you can grab a before and after profile, and see exactly
> what it is that's getting thrashed that you're fixing (may just be everything).

From the profile posted it's the division in page_zone().


-- wli


diff -urpN pernode-2.5.63-bk5-1/include/linux/mm.h pernode-2.5.63-bk5-2/include/linux/mm.h
--- pernode-2.5.63-bk5-1/include/linux/mm.h 2003-03-02 02:55:14.000000000 -0800
+++ pernode-2.5.63-bk5-2/include/linux/mm.h 2003-03-02 12:55:20.000000000 -0800
@@ -316,6 +316,7 @@ static inline void put_page(struct page
* sets it, so none of the operations on it need to be atomic.
*/
#define NODE_SHIFT 4
+#define ZONE_MASK ((1UL << NODE_SHIFT) - 1)
#define ZONE_SHIFT (BITS_PER_LONG - 8)

struct zone;
@@ -324,7 +325,7 @@ DECLARE_PER_NODE(struct zone *[MAX_NR_ZO
static inline struct zone *page_zone(struct page *page)
{
unsigned long zone = page->flags >> ZONE_SHIFT;
- return per_node(zone_table, zone/MAX_NR_ZONES)[zone % MAX_NR_ZONES];
+ return per_node(zone_table, zone >> NODE_SHIFT)[zone & ZONE_MASK];
}

static inline void set_page_zone(struct page *page, unsigned long zone_num)
diff -urpN pernode-2.5.63-bk5-1/mm/page_alloc.c pernode-2.5.63-bk5-2/mm/page_alloc.c
--- pernode-2.5.63-bk5-1/mm/page_alloc.c 2003-03-02 02:55:14.000000000 -0800
+++ pernode-2.5.63-bk5-2/mm/page_alloc.c 2003-03-02 12:15:00.000000000 -0800
@@ -1262,7 +1262,7 @@ static void __init free_area_init_core(s
*/
for (i = 0; i < size; i++) {
struct page *page = lmem_map + local_offset + i;
- set_page_zone(page, nid * MAX_NR_ZONES + j);
+ set_page_zone(page, (nid << NODE_SHIFT) + j);
set_page_count(page, 0);
SetPageReserved(page);
INIT_LIST_HEAD(&page->list);
-
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