linux-kernel - [RFC][PATCH 2/5] PM/Suspend: Do not shrink memory before suspend

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Message-Id: <200905072351.11639.rjw@sisk.pl>
Date:	Thu, 7 May 2009 23:51:10 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	pm list <linux-pm@...ts.linux-foundation.org>
Cc:	Wu Fengguang <fengguang.wu@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>, Pavel Machek <pavel@....cz>,
	Nigel Cunningham <nigel@...onice.net>,
	David Rientjes <rientjes@...gle.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: [RFC][PATCH 2/5] PM/Suspend: Do not shrink memory before suspend

From: Rafael J. Wysocki <rjw@...k.pl>

Remove the shrinking of memory from the suspend-to-RAM code, where
it is not really necessary.

Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
Acked-by: Nigel Cunningham <nigel@...onice.net>
---
 kernel/power/main.c |   20 +-------------------
 mm/vmscan.c         |    4 ++--
 2 files changed, 3 insertions(+), 21 deletions(-)

Index: linux-2.6/kernel/power/main.c
===================================================================
--- linux-2.6.orig/kernel/power/main.c
+++ linux-2.6/kernel/power/main.c
@@ -188,9 +188,6 @@ static void suspend_test_finish(const ch
 
 #endif
 
-/* This is just an arbitrary number */
-#define FREE_PAGE_NUMBER (100)
-
 static struct platform_suspend_ops *suspend_ops;
 
 /**
@@ -226,7 +223,6 @@ int suspend_valid_only_mem(suspend_state
 static int suspend_prepare(void)
 {
 	int error;
-	unsigned int free_pages;
 
 	if (!suspend_ops || !suspend_ops->enter)
 		return -EPERM;
@@ -241,24 +237,10 @@ static int suspend_prepare(void)
 	if (error)
 		goto Finish;
 
-	if (suspend_freeze_processes()) {
-		error = -EAGAIN;
-		goto Thaw;
-	}
-
-	free_pages = global_page_state(NR_FREE_PAGES);
-	if (free_pages < FREE_PAGE_NUMBER) {
-		pr_debug("PM: free some memory\n");
-		shrink_all_memory(FREE_PAGE_NUMBER - free_pages);
-		if (nr_free_pages() < FREE_PAGE_NUMBER) {
-			error = -ENOMEM;
-			printk(KERN_ERR "PM: No enough memory\n");
-		}
-	}
+	error = suspend_freeze_processes();
 	if (!error)
 		return 0;
 
- Thaw:
 	suspend_thaw_processes();
 	usermodehelper_enable();
  Finish:
Index: linux-2.6/mm/vmscan.c
===================================================================
--- linux-2.6.orig/mm/vmscan.c
+++ linux-2.6/mm/vmscan.c
@@ -2054,7 +2054,7 @@ unsigned long global_lru_pages(void)
 		+ global_page_state(NR_INACTIVE_FILE);
 }
 
-#ifdef CONFIG_PM
+#ifdef CONFIG_HIBERNATION
 /*
  * Helper function for shrink_all_memory().  Tries to reclaim 'nr_pages' pages
  * from LRU lists system-wide, for given pass and priority.
@@ -2194,7 +2194,7 @@ out:
 
 	return sc.nr_reclaimed;
 }
-#endif
+#endif /* CONFIG_HIBERNATION */
 
 /* It's optimal to keep kswapds on the same CPUs as their memory, but
    not required for correctness.  So if the last cpu in a node goes

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