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aa-200-active_page_swapout

PATCH Andrew Morton 2 participants 3 messages Mar 20, 2002

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Memory management MGLRU MM reclaim
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Andrew Morton

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#0 lore raw

Last one.

Don't bother checking for active pages in the swapout path.

Not sure about this one. Clearly the page isn't *likely* to be on the active list, because the caller found it on the inactive list. But I don't see any locking which would prevent the page from getting bumped up to the active list in the meanwhile.

Needs more explanation.

=====================================

mm/vmscan.c renamed from mm/vmscan.c~aa-200-active_page_swapout +0 -4
@@ -83,10 +83,6 @@ static inline int try_to_swap_out(struct
 		return 0;
 	}
 
-	/* Don't bother unmapping pages that are active */
-	if (PageActive(page))
-		return 0;
-
 	/* Don't bother replenishing zones not under pressure.. */
 	if (!memclass(page_zone(page), classzone))
 		return 0;

-

#1 lore raw
Quoted 4 lines · Andrew Morton

Don't bother checking for active pages in the swapout path.

Not sure about this one. Clearly the page isn't *likely* to be on the active list, because the caller found it on the inactive list.

Mmmm nope.

The caller of swap_out (shrink_caches) may have been scanning the inactive list, but swap_out itself scans the page tables.

This means it can encounter all kinds of pages, active, inactive and even reserved pages.

Quoted 16 lines
mm/vmscan.c renamed from mm/vmscan.c~aa-200-active_page_swapout +0 -6
@@ -83,10 +83,6 @@ static inline int try_to_swap_out(struct
 		return 0;
 	}
 
-	/* Don't bother unmapping pages that are active */
-	if (PageActive(page))
-		return 0;
-
 	/* Don't bother replenishing zones not under pressure.. */
 	if (!memclass(page_zone(page), classzone))
 		return 0;
 
-
-
Quoted 5 lines

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Rik

Signature · 3 lines
Bravely reimplemented by the knights who say "NIH".

http://www.surriel.com/		http://distro.conectiva.com/
author
#2 lore raw
In reply to Andrew Morton
Quoted 8 lines · Rik van Riel
Quoted 4 lines · Andrew Morton

Don't bother checking for active pages in the swapout path.

Not sure about this one. Clearly the page isn't *likely* to be on the active list, because the caller found it on the inactive list.

Quoted 8 lines

Mmmm nope.

The caller of swap_out (shrink_caches) may have been scanning the inactive list, but swap_out itself scans the page tables.

This means it can encounter all kinds of pages, active, inactive and even reserved pages.

good point :)

So what does the patch do?

-