[PATCH v3 10/11] writeback: make determine_dirtyable_memory() static.

Greg Thelen
2010-10-19T00:43:52Z

The determine_dirtyable_memory() function is not used outside of
page writeback. Make the routine static. No functional change.
Just a cleanup in preparation for a change that adds memcg dirty
limits consideration into global_dirty_limits().

Signed-off-by: Andrea Righi <arighi@develer.com>
Signed-off-by: Greg Thelen <gthelen@google.com>
---
include/linux/writeback.h | 2 -
mm/page-writeback.c | 122 ++++++++++++++++++++++----------------------
2 files changed, 61 insertions(+), 63 deletions(-)

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index c7299d2..c18e374 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -105,8 +105,6 @@ extern int vm_highmem_is_dirtyable;
extern int block_dump;
extern int laptop_mode;

-extern unsigned long determine_dirtyable_memory(void);
-
extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
loff_t *ppos);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 820eb66..a0bb3e2 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -132,6 +132,67 @@ static struct prop_descriptor vm_completions;
static struct prop_descriptor vm_dirties;

/*
+ * Work out the current dirty-memory clamping and background writeout
+ * thresholds.
+ *
+ * The main aim here is to lower them aggressively if there is a lot of mapped
+ * memory around. To avoid stressing page reclaim with lots of unreclaimable
+ * pages. It is better to clamp down on writers than to start swapping, and
+ * performing lots of scanning.
+ *
+ * We only allow 1/2 of the currently-unmapped memory to be dirtied.
+ *
+ * We don't permit the clamping level to fall below 5% - that is getting rather
+ * excessive.
+ *
+ * We make sure that the background writeout level is below the adjusted
+ * clamping level.
+ */
+
+static unsigned long highmem_dirtyable_memory(unsigned long total)
+{
+#ifdef CONFIG_HIGHMEM
+ int node;
+ unsigned long x = 0;
+
+ for_each_node_state(node, N_HIGH_MEMORY) {
+ struct zone *z =
+ &NODE_DATA(node)->node_zones[ZONE_HIGHMEM];
+
+ x += zone_page_state(z, NR_FREE_PAGES) +
+ zone_reclaimable_pages(z);
+ }
+ /*
+ * Make sure that the number of highmem pages is never larger
+ * than the number of the total dirtyable memory. This can only
+ * occur in very strange VM situations but we want to make sure
+ * that this does not occur.
+ */
+ return min(x, total);
+#else
+ return 0;
+#endif
+}
+
+/**
+ * determine_dirtyable_memory - amount of memory that may be used
+ *
+ * Returns the numebr of pages that can currently be freed and used
+ * by the kernel for direct mappings.
+ */
+static unsigned long determine_dirtyable_memory(void)
+{
+ unsigned long x;
+
+ x = global_page_state(NR_FREE_PAGES) + global_reclaimable_pages();
+
+ if (!vm_highmem_is_dirtyable)
+ x -= highmem_dirtyable_memory(x);
+
+ return x + 1; /* Ensure that we never return 0 */
+}
+
+/*
* couple the period to the dirty_ratio:
*
* period/2 ~ roundup_pow_of_two(dirty limit)
@@ -337,67 +398,6 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio)
EXPORT_SYMBOL(bdi_set_max_ratio);

/*
- * Work out the current dirty-memory clamping and background writeout
- * thresholds.
- *
- * The main aim here is to lower them aggressively if there is a lot of mapped
- * memory around. To avoid stressing page reclaim with lots of unreclaimable
- * pages. It is better to clamp down on writers than to start swapping, and
- * performing lots of scanning.
- *
- * We only allow 1/2 of the currently-unmapped memory to be dirtied.
- *
- * We don't permit the clamping level to fall below 5% - that is getting rather
- * excessive.
- *
- * We make sure that the background writeout level is below the adjusted
- * clamping level.
- */
-
-static unsigned long highmem_dirtyable_memory(unsigned long total)
-{
-#ifdef CONFIG_HIGHMEM
- int node;
- unsigned long x = 0;
-
- for_each_node_state(node, N_HIGH_MEMORY) {
- struct zone *z =
- &NODE_DATA(node)->node_zones[ZONE_HIGHMEM];
-
- x += zone_page_state(z, NR_FREE_PAGES) +
- zone_reclaimable_pages(z);
- }
- /*
- * Make sure that the number of highmem pages is never larger
- * than the number of the total dirtyable memory. This can only
- * occur in very strange VM situations but we want to make sure
- * that this does not occur.
- */
- return min(x, total);
-#else
- return 0;
-#endif
-}
-
-/**
- * determine_dirtyable_memory - amount of memory that may be used
- *
- * Returns the numebr of pages that can currently be freed and used
- * by the kernel for direct mappings.
- */
-unsigned long determine_dirtyable_memory(void)
-{
- unsigned long x;
-
- x = global_page_state(NR_FREE_PAGES) + global_reclaimable_pages();
-
- if (!vm_highmem_is_dirtyable)
- x -= highmem_dirtyable_memory(x);
-
- return x + 1; /* Ensure that we never return 0 */
-}
-
-/*
* global_dirty_limits - background-writeback and dirty-throttling thresholds
*
* Calculate the dirty thresholds based on sysctl parameters
--
1.7.1