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Subject[RFT][PATCH 3/3] swsusp: improve freeing of memory
Date
This patch makes swsusp free only as much memory as needed and not as much
as possible.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

include/linux/suspend.h | 2 -
kernel/power/disk.c | 30 ++--------------------
kernel/power/power.h | 20 ++++++++++++--
kernel/power/snapshot.c | 65 ++++++++++++++++++++++++++++++++++++++++++++----
kernel/power/swsusp.c | 45 ++++++++++++++++++++++++++++++++-
5 files changed, 125 insertions(+), 37 deletions(-)
Index: linux-2.6.14-mm2/kernel/power/disk.c
===================================================================
--- linux-2.6.14-mm2.orig/kernel/power/disk.c 2005-11-12 12:07:47.000000000 +0100
+++ linux-2.6.14-mm2/kernel/power/disk.c 2005-11-12 12:10:54.000000000 +0100
@@ -24,6 +24,7 @@

extern suspend_disk_method_t pm_disk_mode;

+extern int swsusp_shrink_memory(void);
extern int swsusp_suspend(void);
extern int swsusp_write(struct pbe *pblist, unsigned int nr_pages);
extern int swsusp_check(void);
@@ -73,31 +74,6 @@
static int in_suspend __nosavedata = 0;


-/**
- * free_some_memory - Try to free as much memory as possible
- *
- * ... but do not OOM-kill anyone
- *
- * Notice: all userland should be stopped at this point, or
- * livelock is possible.
- */
-
-static void free_some_memory(void)
-{
- unsigned int i = 0;
- unsigned int tmp;
- unsigned long pages = 0;
- char *p = "-\\|/";
-
- printk("Freeing memory... ");
- while ((tmp = shrink_all_memory(10000))) {
- pages += tmp;
- printk("\b%c", p[i++ % 4]);
- }
- printk("\bdone (%li pages freed)\n", pages);
-}
-
-
static inline void platform_finish(void)
{
if (pm_disk_mode == PM_DISK_PLATFORM) {
@@ -127,8 +103,8 @@
}

/* Free memory before shutting down devices. */
- free_some_memory();
- return 0;
+ if (!(error = swsusp_shrink_memory()))
+ return 0;
thaw:
thaw_processes();
enable_nonboot_cpus();
Index: linux-2.6.14-mm2/kernel/power/power.h
===================================================================
--- linux-2.6.14-mm2.orig/kernel/power/power.h 2005-11-12 12:07:47.000000000 +0100
+++ linux-2.6.14-mm2/kernel/power/power.h 2005-11-12 12:10:54.000000000 +0100
@@ -49,18 +49,32 @@
extern int pm_prepare_console(void);
extern void pm_restore_console(void);

-
/* References to section boundaries */
extern const void __nosave_begin, __nosave_end;

extern unsigned int nr_copy_pages;
-extern suspend_pagedir_t *pagedir_nosave;
-extern suspend_pagedir_t *pagedir_save;
+extern struct pbe *pagedir_nosave;
+
+/*
+ * This compilation switch determines the way in which memory will be freed
+ * during suspend. If defined, only as much memory will be freed as needed
+ * to complete the suspend. Otherwise, the largest possible amount of memory
+ * will be freed.
+ */
+#define OPPORTUNISTIC_SHRINKING 1
+
+/*
+ * During suspend, on each attempt to free some more memory SHRINK_BITE
+ * is used as the number of pages to free
+ */
+#define SHRINK_BITE 10000

extern asmlinkage int swsusp_arch_suspend(void);
extern asmlinkage int swsusp_arch_resume(void);

+extern unsigned int count_data_pages(void);
extern void free_pagedir(struct pbe *pblist);
+extern void release_eaten_pages(void);
extern struct pbe *alloc_pagedir(unsigned nr_pages, gfp_t gfp_mask, int safe_needed);
extern void swsusp_free(void);
extern int alloc_data_pages(struct pbe *pblist, gfp_t gfp_mask, int safe_needed);
Index: linux-2.6.14-mm2/kernel/power/snapshot.c
===================================================================
--- linux-2.6.14-mm2.orig/kernel/power/snapshot.c 2005-11-12 12:07:47.000000000 +0100
+++ linux-2.6.14-mm2/kernel/power/snapshot.c 2005-11-12 12:10:54.000000000 +0100
@@ -37,6 +37,31 @@
unsigned int nr_copy_pages = 0;

#ifdef CONFIG_HIGHMEM
+unsigned int count_highmem_pages(void)
+{
+ struct zone *zone;
+ unsigned long zone_pfn;
+ unsigned int n = 0;
+
+ for_each_zone (zone)
+ if (is_highmem(zone)) {
+ mark_free_pages(zone);
+ for (zone_pfn = 0; zone_pfn < zone->spanned_pages; zone_pfn++) {
+ struct page *page;
+ unsigned long pfn = zone_pfn + zone->zone_start_pfn;
+ if (!pfn_valid(pfn))
+ continue;
+ page = pfn_to_page(pfn);
+ if (PageReserved(page))
+ continue;
+ if (PageNosaveFree(page))
+ continue;
+ n++;
+ }
+ }
+ return n;
+}
+
struct highmem_page {
char *data;
struct page *page;
@@ -152,17 +177,15 @@
BUG_ON(PageReserved(page) && PageNosave(page));
if (PageNosave(page))
return 0;
- if (PageReserved(page) && pfn_is_nosave(pfn)) {
- pr_debug("[nosave pfn 0x%lx]", pfn);
+ if (PageReserved(page) && pfn_is_nosave(pfn))
return 0;
- }
if (PageNosaveFree(page))
return 0;

return 1;
}

-static unsigned count_data_pages(void)
+unsigned int count_data_pages(void)
{
struct zone *zone;
unsigned long zone_pfn;
@@ -267,6 +290,35 @@
}

/**
+ * On resume it is necessary to trace and eventually free the unsafe
+ * pages that have been allocated, because they are needed for I/O
+ * (on x86-64 we likely will "eat" these pages once again while
+ * creating the temporary page translation tables)
+ */
+
+struct eaten_page {
+ struct eaten_page *next;
+ char padding[PAGE_SIZE - sizeof(void *)];
+};
+
+static struct eaten_page *eaten_pages = NULL;
+
+void release_eaten_pages(void)
+{
+ struct eaten_page *p, *q;
+
+ p = eaten_pages;
+ while (p) {
+ q = p->next;
+ /* We don't want swsusp_free() to free this page again */
+ ClearPageNosave(virt_to_page(p));
+ free_page((unsigned long)p);
+ p = q;
+ }
+ eaten_pages = NULL;
+}
+
+/**
* @safe_needed - on resume, for storing the PBE list and the image,
* we can only use memory pages that do not conflict with the pages
* which had been used before suspend.
@@ -284,9 +336,12 @@
if (safe_needed)
do {
res = (void *)get_zeroed_page(gfp_mask);
- if (res && PageNosaveFree(virt_to_page(res)))
+ if (res && PageNosaveFree(virt_to_page(res))) {
/* This is for swsusp_free() */
SetPageNosave(virt_to_page(res));
+ ((struct eaten_page *)res)->next = eaten_pages;
+ eaten_pages = res;
+ }
} while (res && PageNosaveFree(virt_to_page(res)));
else
res = (void *)get_zeroed_page(gfp_mask);
Index: linux-2.6.14-mm2/kernel/power/swsusp.c
===================================================================
--- linux-2.6.14-mm2.orig/kernel/power/swsusp.c 2005-11-12 12:07:47.000000000 +0100
+++ linux-2.6.14-mm2/kernel/power/swsusp.c 2005-11-12 12:10:54.000000000 +0100
@@ -74,11 +74,13 @@
#include "power.h"

#ifdef CONFIG_HIGHMEM
+unsigned int count_highmem_pages(void);
int save_highmem(void);
int restore_highmem(void);
#else
static int save_highmem(void) { return 0; }
static int restore_highmem(void) { return 0; }
+static unsigned int count_highmem_pages(void) { return 0; }
#endif

extern char resume_file[];
@@ -616,6 +618,45 @@
return error;
}

+/**
+ * swsusp_shrink_memory - Try to free as much memory as needed
+ *
+ * ... but do not OOM-kill anyone
+ *
+ * Notice: all userland should be stopped before it is called, or
+ * livelock is possible.
+ */
+
+int swsusp_shrink_memory(void)
+{
+ unsigned long cnt = SHRINK_BITE;
+ long tmp;
+ unsigned long pages = 0;
+ unsigned int i = 0;
+ char *p = "-\\|/";
+
+ printk("Shrinking memory... ");
+ do {
+#ifdef OPPORTUNISTIC_SHRINKING
+ cnt = count_data_pages() + count_highmem_pages();
+ cnt += (cnt + PBES_PER_PAGE - 1) / PBES_PER_PAGE +
+ PAGES_FOR_IO;
+ tmp = cnt - nr_free_pages();
+ if (tmp > 0) {
+ cnt = shrink_all_memory(SHRINK_BITE);
+ pages += cnt;
+ }
+#else
+ tmp = shrink_all_memory(SHRINK_BITE);
+ pages += tmp;
+#endif
+ printk("\b%c", p[i++%4]);
+ } while (tmp > 0 && cnt > 0);
+ printk("\bdone (%lu pages freed)\n", pages);
+
+ return tmp > 0 ? -ENOMEM : 0;
+}
+
int swsusp_suspend(void)
{
int error;
@@ -1035,8 +1076,10 @@
/* Allocate memory for the image and read the data from swap */
if (!error)
error = alloc_data_pages(pblist, GFP_ATOMIC, 1);
- if (!error)
+ if (!error) {
+ release_eaten_pages();
error = load_image_data(pblist, &handle, nr_pages);
+ }
if (!error)
*pblist_ptr = pblist;
}
Index: linux-2.6.14-mm2/include/linux/suspend.h
===================================================================
--- linux-2.6.14-mm2.orig/include/linux/suspend.h 2005-11-12 12:07:47.000000000 +0100
+++ linux-2.6.14-mm2/include/linux/suspend.h 2005-11-12 12:10:54.000000000 +0100
@@ -73,6 +73,6 @@
* XXX: We try to keep some more pages free so that I/O operations succeed
* without paging. Might this be more?
*/
-#define PAGES_FOR_IO 512
+#define PAGES_FOR_IO 1024

#endif /* _LINUX_SWSUSP_H */
-
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