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From: Nick Piggin <npiggin@suse.de>
To: Linus Torvalds <torvalds@osdl.org>, Andrew Morton <akpm@osdl.org>
Cc: Nick Piggin <npiggin@suse.de>,
	Linux Memory Management <linux-mm@kvack.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: [patch 2/6] mm: PageLRU no testset
Date: Thu, 19 Jan 2006 20:23:01 +0100 (CET)	[thread overview]
Message-ID: <20060119192150.11913.81639.sendpatchset@linux.site> (raw)
In-Reply-To: <20060119192131.11913.27564.sendpatchset@linux.site>

PG_lru is protected by zone->lru_lock. It does not need TestSet/TestClear
operations.

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

Index: linux-2.6/mm/vmscan.c
===================================================================
--- linux-2.6.orig/mm/vmscan.c
+++ linux-2.6/mm/vmscan.c
@@ -780,9 +780,10 @@ int isolate_lru_page(struct page *page)
 	if (PageLRU(page)) {
 		struct zone *zone = page_zone(page);
 		spin_lock_irq(&zone->lru_lock);
-		if (TestClearPageLRU(page)) {
+		if (PageLRU(page)) {
 			ret = 1;
 			get_page(page);
+			ClearPageLRU(page);
 			if (PageActive(page))
 				del_page_from_active_list(zone, page);
 			else
@@ -823,6 +824,8 @@ static int isolate_lru_pages(int nr_to_s
 		page = lru_to_page(src);
 		prefetchw_prev_lru_page(page, src, flags);
 
+		BUG_ON(!PageLRU(page));
+
 		list_del(&page->lru);
 		if (unlikely(get_page_testone(page))) {
 			/*
@@ -838,8 +841,7 @@ static int isolate_lru_pages(int nr_to_s
 		 * the page is not being freed elsewhere -- the page release
 		 * code relies on it.
 		 */
-		if (!TestClearPageLRU(page))
-			BUG();
+		ClearPageLRU(page);
 		list_add(&page->lru, dst);
 		nr_taken++;
 	}
@@ -894,8 +896,8 @@ static void shrink_cache(struct zone *zo
 		 */
 		while (!list_empty(&page_list)) {
 			page = lru_to_page(&page_list);
-			if (TestSetPageLRU(page))
-				BUG();
+			BUG_ON(PageLRU(page));
+			SetPageLRU(page);
 			list_del(&page->lru);
 			if (PageActive(page))
 				add_page_to_active_list(zone, page);
@@ -1007,8 +1009,8 @@ refill_inactive_zone(struct zone *zone, 
 	while (!list_empty(&l_inactive)) {
 		page = lru_to_page(&l_inactive);
 		prefetchw_prev_lru_page(page, &l_inactive, flags);
-		if (TestSetPageLRU(page))
-			BUG();
+		BUG_ON(PageLRU(page));
+		SetPageLRU(page);
 		if (!TestClearPageActive(page))
 			BUG();
 		list_move(&page->lru, &zone->inactive_list);
@@ -1036,8 +1038,8 @@ refill_inactive_zone(struct zone *zone, 
 	while (!list_empty(&l_active)) {
 		page = lru_to_page(&l_active);
 		prefetchw_prev_lru_page(page, &l_active, flags);
-		if (TestSetPageLRU(page))
-			BUG();
+		BUG_ON(PageLRU(page));
+		SetPageLRU(page);
 		BUG_ON(!PageActive(page));
 		list_move(&page->lru, &zone->active_list);
 		pgmoved++;
Index: linux-2.6/mm/swap.c
===================================================================
--- linux-2.6.orig/mm/swap.c
+++ linux-2.6/mm/swap.c
@@ -211,8 +211,8 @@ void fastcall __page_cache_release(struc
 
 		struct zone *zone = page_zone(page);
 		spin_lock_irqsave(&zone->lru_lock, flags);
-		if (!TestClearPageLRU(page))
-			BUG();
+		BUG_ON(!PageLRU(page));
+		ClearPageLRU(page);
 		del_page_from_lru(zone, page);
 		spin_unlock_irqrestore(&zone->lru_lock, flags);
 	}
@@ -255,8 +255,8 @@ void release_pages(struct page **pages, 
 				zone = pagezone;
 				spin_lock_irq(&zone->lru_lock);
 			}
-			if (!TestClearPageLRU(page))
-				BUG();
+			BUG_ON(!PageLRU(page));
+			ClearPageLRU(page);
 			del_page_from_lru(zone, page);
 		}
 
@@ -335,8 +335,8 @@ void __pagevec_lru_add(struct pagevec *p
 			zone = pagezone;
 			spin_lock_irq(&zone->lru_lock);
 		}
-		if (TestSetPageLRU(page))
-			BUG();
+		BUG_ON(PageLRU(page));
+		SetPageLRU(page);
 		add_page_to_inactive_list(zone, page);
 	}
 	if (zone)
@@ -362,8 +362,8 @@ void __pagevec_lru_add_active(struct pag
 			zone = pagezone;
 			spin_lock_irq(&zone->lru_lock);
 		}
-		if (TestSetPageLRU(page))
-			BUG();
+		BUG_ON(PageLRU(page));
+		SetPageLRU(page);
 		if (TestSetPageActive(page))
 			BUG();
 		add_page_to_active_list(zone, page);
Index: linux-2.6/include/linux/page-flags.h
===================================================================
--- linux-2.6.orig/include/linux/page-flags.h
+++ linux-2.6/include/linux/page-flags.h
@@ -244,10 +244,9 @@ extern void __mod_page_state_offset(unsi
 #define __ClearPageDirty(page)	__clear_bit(PG_dirty, &(page)->flags)
 #define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)
 
-#define SetPageLRU(page)	set_bit(PG_lru, &(page)->flags)
 #define PageLRU(page)		test_bit(PG_lru, &(page)->flags)
-#define TestSetPageLRU(page)	test_and_set_bit(PG_lru, &(page)->flags)
-#define TestClearPageLRU(page)	test_and_clear_bit(PG_lru, &(page)->flags)
+#define SetPageLRU(page)	set_bit(PG_lru, &(page)->flags)
+#define ClearPageLRU(page)	clear_bit(PG_lru, &(page)->flags)
 
 #define PageActive(page)	test_bit(PG_active, &(page)->flags)
 #define SetPageActive(page)	set_bit(PG_active, &(page)->flags)

  parent reply	other threads:[~2006-01-19 19:23 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-01-19 19:22 [patch 0/6] mm: optimisations and page ref simplifications Nick Piggin
2006-01-19 19:22 ` [patch 1/6] mm: never ClearPageLRU released pages Nick Piggin
2006-01-19 19:23 ` Nick Piggin [this message]
2006-01-19 19:23 ` [patch 3/6] mm: PageActive no testset Nick Piggin
2006-01-19 19:23 ` [patch 4/6] mm: less atomic ops Nick Piggin
2006-01-19 19:23 ` [patch 5/6] mm: simplify vmscan vs release refcounting Nick Piggin
2006-01-19 19:35   ` Linus Torvalds
2006-01-19 19:53     ` Nick Piggin
2006-01-19 19:23 ` [patch 6/6] mm: de-skew page refcounting Nick Piggin

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