Re: Results: 2.2.0-pre5 vs arcavm10 vs arcavm9 vs arcavm7

[Andrea Arcangeli <andrea@e-mind.com>]

On 7 Jan 1999, Zlatko Calusic wrote:

> 2) In pre-5, under heavy load, free memory is hovering around
> freepages.min instead of being somewhere between freepages.low &
> freepages.max. This could make trouble for bursts of atomic
> allocations (networking!).

Agreed and I just fixed that with my updates to the memory trashing
heuristic (see also the second patch in one of my last emails). 

A new minimal patch against 2.2.0-pre5 is this:

Index: page_alloc.c
===================================================================
RCS file: /var/cvs/linux/mm/page_alloc.c,v
retrieving revision 1.1.1.6
diff -u -2 -r1.1.1.6 page_alloc.c
--- page_alloc.c	1999/01/07 11:21:35	1.1.1.6
+++ linux/mm/page_alloc.c	1999/01/07 19:34:58
@@ -4,4 +4,5 @@
  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  *  Swap reorganised 29.12.95, Stephen Tweedie
+ *  trashing_memory heuristic. Copyright (C) 1999  Andrea Arcangeli
  */
 
@@ -259,7 +260,4 @@
 		 * to free things up until things are better.
 		 *
-		 * Normally we shouldn't ever have to do this, with
-		 * kswapd doing this in the background.
-		 *
 		 * Most notably, this puts most of the onus of
 		 * freeing up memory on the processes that _use_
@@ -269,8 +267,9 @@
 			if (!current->trashing_memory)
 				goto ok_to_allocate;
-			if (nr_free_pages > freepages.low) {
+			if (nr_free_pages > freepages.high) {
 				current->trashing_memory = 0;
 				goto ok_to_allocate;
-			}
+			} else if (nr_free_pages > freepages.low)
+				goto ok_to_allocate;
 		}
 		/*



The problem is that I don't know if it's going to hurt performances... If
somebody would try it out would be helpful... I don't think it can 
hurt but...

Andrea Arcangeli

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