[patch] mm: cleanup bootmem

* [patch] mm: cleanup bootmem
@ 2006-01-14 12:42 Nick Piggin
  2006-01-14 12:47 ` Nick Piggin
  2006-01-14 17:50 ` Linus Torvalds
  0 siblings, 2 replies; 9+ messages in thread
From: Nick Piggin @ 2006-01-14 12:42 UTC (permalink / raw)
  To: Andrew Morton, David Howells; +Cc: Linus Torvalds, Linux Kernel Mailing List

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Objections?

-- 
SUSE Labs, Novell Inc.


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The bootmem code added to page_alloc.c duplicated some page freeing code
that it really doesn't need to because it is not so performance critical.

While we're here, make prefetching work properly by actually prefetching
the page we're about to use before prefetching ahead to the next one (ie.
get the most important transaction started first). Also prefetch just a
single page ahead rather than leaving a gap of 16.

Signed-off-by: Nick Piggin <npiggin@suse.de>

Index: linux-2.6/mm/page_alloc.c
===================================================================

--- linux-2.6.orig/mm/page_alloc.c
+++ linux-2.6/mm/page_alloc.c
@@ -55,8 +55,6 @@ unsigned long totalhigh_pages __read_mos
 long nr_swap_pages;
 int percpu_pagelist_fraction;
 
-static void fastcall free_hot_cold_page(struct page *page, int cold);
-
 /*
  * results with 256, 32 in the lowmem_reserve sysctl:
  *	1G machine -> (16M dma, 800M-16M normal, 1G-800M high)
@@ -444,28 +442,23 @@ void fastcall __init __free_pages_bootme
 	if (order == 0) {
 		__ClearPageReserved(page);
 		set_page_count(page, 0);
-
-		free_hot_cold_page(page, 0);
+		set_page_refs(page, 0);
+		__free_page(page);
 	} else {
-		LIST_HEAD(list);
 		int loop;
 
+		prefetchw(page);
 		for (loop = 0; loop < BITS_PER_LONG; loop++) {
 			struct page *p = &page[loop];
 
-			if (loop + 16 < BITS_PER_LONG)
-				prefetchw(p + 16);
+			if (loop + 1 < BITS_PER_LONG)
+				prefetchw(p + 1);
 			__ClearPageReserved(p);
 			set_page_count(p, 0);
 		}
 
-		arch_free_page(page, order);
-
-		mod_page_state(pgfree, 1 << order);
-
-		list_add(&page->lru, &list);
-		kernel_map_pages(page, 1 << order, 0);
-		free_pages_bulk(page_zone(page), 1, &list, order);
+		set_page_refs(page, order);
+		__free_pages(page, order);
 	}
 }
 

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