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-rw-r--r--mm/page-writeback.c41
1 files changed, 18 insertions, 23 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 1d2fc89ca56d..be0efbde4994 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -133,11 +133,9 @@ get_dirty_limits(long *pbackground, long *pdirty,
#ifdef CONFIG_HIGHMEM
/*
- * If this mapping can only allocate from low memory,
- * we exclude high memory from our count.
+ * We always exclude high memory from our count.
*/
- if (mapping && !(mapping_gfp_mask(mapping) & __GFP_HIGHMEM))
- available_memory -= totalhigh_pages;
+ available_memory -= totalhigh_pages;
#endif
@@ -526,28 +524,25 @@ static struct notifier_block __cpuinitdata ratelimit_nb = {
};
/*
- * If the machine has a large highmem:lowmem ratio then scale back the default
- * dirty memory thresholds: allowing too much dirty highmem pins an excessive
- * number of buffer_heads.
+ * Called early on to tune the page writeback dirty limits.
+ *
+ * We used to scale dirty pages according to how total memory
+ * related to pages that could be allocated for buffers (by
+ * comparing nr_free_buffer_pages() to vm_total_pages.
+ *
+ * However, that was when we used "dirty_ratio" to scale with
+ * all memory, and we don't do that any more. "dirty_ratio"
+ * is now applied to total non-HIGHPAGE memory (by subtracting
+ * totalhigh_pages from vm_total_pages), and as such we can't
+ * get into the old insane situation any more where we had
+ * large amounts of dirty pages compared to a small amount of
+ * non-HIGHMEM memory.
+ *
+ * But we might still want to scale the dirty_ratio by how
+ * much memory the box has..
*/
void __init page_writeback_init(void)
{
- long buffer_pages = nr_free_buffer_pages();
- long correction;
-
- correction = (100 * 4 * buffer_pages) / vm_total_pages;
-
- if (correction < 100) {
- dirty_background_ratio *= correction;
- dirty_background_ratio /= 100;
- vm_dirty_ratio *= correction;
- vm_dirty_ratio /= 100;
-
- if (dirty_background_ratio <= 0)
- dirty_background_ratio = 1;
- if (vm_dirty_ratio <= 0)
- vm_dirty_ratio = 1;
- }
mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
writeback_set_ratelimit();
register_cpu_notifier(&ratelimit_nb);