Re: PATCH: Further aacraid work

From: William Lee Irwin III
Date: Thu Jun 17 2004 - 15:51:23 EST


On Thu, Jun 17, 2004 at 01:54:38PM -0400, Salyzyn, Mark wrote:
>> And I might add, undoing the entropy to result in the descending page
>> list (but that is the forth time I've said this).
>> I ran heavy sequential load overnight and continued to have this
>> characteristic when taking snapshots of command SG lists. The average SG
>> element size statistically was 4168 bytes.

On Thu, Jun 17, 2004 at 04:38:42PM -0400, Alan Cox wrote:
> What do the stats look like with the patch Andrew Morton (I think) posted
> to reverse the page order from the allocator ?

Say, could you guys try this? jejb seemed to get decent results with it.


===== mm/page_alloc.c 1.211 vs edited =====
--- 1.211/mm/page_alloc.c Sat Jun 12 20:52:26 2004
+++ edited/mm/page_alloc.c Thu Jun 17 13:46:36 2004
@@ -297,14 +297,12 @@
unsigned long size = 1 << high;

while (high > low) {
- BUG_ON(bad_range(zone, page));
area--;
high--;
size >>= 1;
- list_add(&page->lru, &area->free_list);
- MARK_USED(index, high, area);
- index += size;
- page += size;
+ BUG_ON(bad_range(zone, &page[size]));
+ list_add(&page[size].lru, &area->free_list);
+ MARK_USED(index + size, high, area);
}
return page;
}
-
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