*/
static struct prop_descriptor vm_completions;
+/*
+ * 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) - z->dirty_balance_reserve;
+ }
+ /*
+ * 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() -
+ dirty_balance_reserve;
+
+ 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:
*
return ret;
}
-
int dirty_bytes_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
loff_t *ppos)
}
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 */
-}
-
static unsigned long dirty_freerun_ceiling(unsigned long thresh,
unsigned long bg_thresh)
{
*/
setpoint = (freerun + limit) / 2;
x = div64_s64(((s64)setpoint - (s64)dirty) << RATELIMIT_CALC_SHIFT,
- limit - setpoint + 1);
+ (limit - setpoint) | 1);
pos_ratio = x;
pos_ratio = pos_ratio * x >> RATELIMIT_CALC_SHIFT;
pos_ratio = pos_ratio * x >> RATELIMIT_CALC_SHIFT;
* scale global setpoint to bdi's:
* bdi_setpoint = setpoint * bdi_thresh / thresh
*/
- x = div_u64((u64)bdi_thresh << 16, thresh + 1);
+ x = div_u64((u64)bdi_thresh << 16, thresh | 1);
bdi_setpoint = setpoint * (u64)x >> 16;
/*
* Use span=(8*write_bw) in single bdi case as indicated by
if (bdi_dirty < x_intercept - span / 4) {
pos_ratio = div64_u64(pos_ratio * (x_intercept - bdi_dirty),
- x_intercept - bdi_setpoint + 1);
+ (x_intercept - bdi_setpoint) | 1);
} else
pos_ratio /= 4;
* bw * elapsed + write_bandwidth * (period - elapsed)
* write_bandwidth = ---------------------------------------------------
* period
+ *
+ * @written may have decreased due to account_page_redirty().
+ * Avoid underflowing @bw calculation.
*/
- bw = written - bdi->written_stamp;
+ bw = written - min(written, bdi->written_stamp);
bw *= HZ;
if (unlikely(elapsed > period)) {
do_div(bw, elapsed);
git.openpandora.org / pandora-kernel.git / blobdiff