diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 71df353e367c9e8c3f2833fe7114c875a6d49d3b..32e94635484f968c40291264d6e5b7df14d813ae 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -1385,6 +1385,15 @@ swapcache reclaim. Decreasing vfs_cache_pressure causes the kernel to prefer
to retain dentry and inode caches. Increasing vfs_cache_pressure beyond 100
causes the kernel to prefer to reclaim dentries and inodes.
+dirty_background_bytes
+----------------------
+
+Contains the amount of dirty memory at which the pdflush background writeback
+daemon will start writeback.
+
+If dirty_background_bytes is written, dirty_background_ratio becomes a function
+of its value (dirty_background_bytes / the amount of dirtyable system memory).
+
dirty_background_ratio
----------------------
@@ -1393,14 +1402,29 @@ pages + file cache, not including locked pages and HugePages), the number of
pages at which the pdflush background writeback daemon will start writing out
dirty data.
+If dirty_background_ratio is written, dirty_background_bytes becomes a function
+of its value (dirty_background_ratio * the amount of dirtyable system memory).
+
+dirty_bytes
+-----------
+
+Contains the amount of dirty memory at which a process generating disk writes
+will itself start writeback.
+
+If dirty_bytes is written, dirty_ratio becomes a function of its value
+(dirty_bytes / the amount of dirtyable system memory).
+
dirty_ratio
------------------
+-----------
Contains, as a percentage of the dirtyable system memory (free pages + mapped
pages + file cache, not including locked pages and HugePages), the number of
pages at which a process which is generating disk writes will itself start
writing out dirty data.
+If dirty_ratio is written, dirty_bytes becomes a function of its value
+(dirty_ratio * the amount of dirtyable system memory).
+
dirty_writeback_centisecs
-------------------------
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index d79eeda7a699cbeb72ad0a03332388f8d8a68eeb..cd05994a49e69795db29f75675180371e1fe3ae4 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -41,7 +41,8 @@ Currently, these files are in /proc/sys/vm:
==============================================================
-dirty_ratio, dirty_background_ratio, dirty_expire_centisecs,
+dirty_bytes, dirty_ratio, dirty_background_bytes,
+dirty_background_ratio, dirty_expire_centisecs,
dirty_writeback_centisecs, highmem_is_dirtyable,
vfs_cache_pressure, laptop_mode, block_dump, swap_token_timeout,
drop-caches, hugepages_treat_as_movable:
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 259e9ea58cab87045da46ac0557f4b1b5d83abc1..bb28c975c1d761fa5b3d594fab720f395dd7fab6 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -107,7 +107,9 @@ void throttle_vm_writeout(gfp_t gfp_mask);
/* These are exported to sysctl. */
extern int dirty_background_ratio;
+extern unsigned long dirty_background_bytes;
extern int vm_dirty_ratio;
+extern unsigned long vm_dirty_bytes;
extern int dirty_writeback_interval;
extern int dirty_expire_interval;
extern int vm_highmem_is_dirtyable;
@@ -116,9 +118,18 @@ extern int laptop_mode;
extern unsigned long determine_dirtyable_memory(void);
+extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
+ struct file *filp, void __user *buffer, size_t *lenp,
+ loff_t *ppos);
+extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
+ struct file *filp, void __user *buffer, size_t *lenp,
+ loff_t *ppos);
extern int dirty_ratio_handler(struct ctl_table *table, int write,
struct file *filp, void __user *buffer, size_t *lenp,
loff_t *ppos);
+extern int dirty_bytes_handler(struct ctl_table *table, int write,
+ struct file *filp, void __user *buffer, size_t *lenp,
+ loff_t *ppos);
struct ctl_table;
struct file;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index ff6d45c7626f09e183913072f0649d075f028c6a..92f6e5bc3c24f2700b88e31a689f642a83a29a4b 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -87,10 +87,6 @@ extern int rcutorture_runnable;
#endif /* #ifdef CONFIG_RCU_TORTURE_TEST */
/* Constants used for minimum and maximum */
-#if defined(CONFIG_HIGHMEM) || defined(CONFIG_DETECT_SOFTLOCKUP)
-static int one = 1;
-#endif
-
#ifdef CONFIG_DETECT_SOFTLOCKUP
static int sixty = 60;
static int neg_one = -1;
@@ -101,6 +97,7 @@ static int two = 2;
#endif
static int zero;
+static int one = 1;
static int one_hundred = 100;
/* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
@@ -952,11 +949,21 @@ static struct ctl_table vm_table[] = {
.data = &dirty_background_ratio,
.maxlen = sizeof(dirty_background_ratio),
.mode = 0644,
- .proc_handler = &proc_dointvec_minmax,
+ .proc_handler = &dirty_background_ratio_handler,
.strategy = &sysctl_intvec,
.extra1 = &zero,
.extra2 = &one_hundred,
},
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "dirty_background_bytes",
+ .data = &dirty_background_bytes,
+ .maxlen = sizeof(dirty_background_bytes),
+ .mode = 0644,
+ .proc_handler = &dirty_background_bytes_handler,
+ .strategy = &sysctl_intvec,
+ .extra1 = &one,
+ },
{
.ctl_name = VM_DIRTY_RATIO,
.procname = "dirty_ratio",
@@ -968,6 +975,16 @@ static struct ctl_table vm_table[] = {
.extra1 = &zero,
.extra2 = &one_hundred,
},
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "dirty_bytes",
+ .data = &vm_dirty_bytes,
+ .maxlen = sizeof(vm_dirty_bytes),
+ .mode = 0644,
+ .proc_handler = &dirty_bytes_handler,
+ .strategy = &sysctl_intvec,
+ .extra1 = &one,
+ },
{
.procname = "dirty_writeback_centisecs",
.data = &dirty_writeback_interval,
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 4d4074cff300555aa1cb3608a63a85c82ebb0b71..b493db7841dc6c2db77d10eab751f6e1f62e7355 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -68,6 +68,12 @@ static inline long sync_writeback_pages(void)
*/
int dirty_background_ratio = 5;
+/*
+ * dirty_background_bytes starts at 0 (disabled) so that it is a function of
+ * dirty_background_ratio * the amount of dirtyable memory
+ */
+unsigned long dirty_background_bytes;
+
/*
* free highmem will not be subtracted from the total free memory
* for calculating free ratios if vm_highmem_is_dirtyable is true
@@ -79,6 +85,12 @@ int vm_highmem_is_dirtyable;
*/
int vm_dirty_ratio = 10;
+/*
+ * vm_dirty_bytes starts at 0 (disabled) so that it is a function of
+ * vm_dirty_ratio * the amount of dirtyable memory
+ */
+unsigned long vm_dirty_bytes;
+
/*
* The interval between `kupdate'-style writebacks, in jiffies
*/
@@ -135,23 +147,75 @@ static int calc_period_shift(void)
{
unsigned long dirty_total;
- dirty_total = (vm_dirty_ratio * determine_dirtyable_memory()) / 100;
+ if (vm_dirty_bytes)
+ dirty_total = vm_dirty_bytes / PAGE_SIZE;
+ else
+ dirty_total = (vm_dirty_ratio * determine_dirtyable_memory()) /
+ 100;
return 2 + ilog2(dirty_total - 1);
}
/*
- * update the period when the dirty ratio changes.
+ * update the period when the dirty threshold changes.
*/
+static void update_completion_period(void)
+{
+ int shift = calc_period_shift();
+ prop_change_shift(&vm_completions, shift);
+ prop_change_shift(&vm_dirties, shift);
+}
+
+int dirty_background_ratio_handler(struct ctl_table *table, int write,
+ struct file *filp, void __user *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ int ret;
+
+ ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
+ if (ret == 0 && write)
+ dirty_background_bytes = 0;
+ return ret;
+}
+
+int dirty_background_bytes_handler(struct ctl_table *table, int write,
+ struct file *filp, void __user *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ int ret;
+
+ ret = proc_doulongvec_minmax(table, write, filp, buffer, lenp, ppos);
+ if (ret == 0 && write)
+ dirty_background_ratio = 0;
+ return ret;
+}
+
int dirty_ratio_handler(struct ctl_table *table, int write,
struct file *filp, void __user *buffer, size_t *lenp,
loff_t *ppos)
{
int old_ratio = vm_dirty_ratio;
- int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
+ int ret;
+
+ ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
if (ret == 0 && write && vm_dirty_ratio != old_ratio) {
- int shift = calc_period_shift();
- prop_change_shift(&vm_completions, shift);
- prop_change_shift(&vm_dirties, shift);
+ update_completion_period();
+ vm_dirty_bytes = 0;
+ }
+ return ret;
+}
+
+
+int dirty_bytes_handler(struct ctl_table *table, int write,
+ struct file *filp, void __user *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ int old_bytes = vm_dirty_bytes;
+ int ret;
+
+ ret = proc_doulongvec_minmax(table, write, filp, buffer, lenp, ppos);
+ if (ret == 0 && write && vm_dirty_bytes != old_bytes) {
+ update_completion_period();
+ vm_dirty_ratio = 0;
}
return ret;
}
@@ -365,23 +429,29 @@ void
get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
unsigned long *pbdi_dirty, struct backing_dev_info *bdi)
{
- int background_ratio; /* Percentages */
- int dirty_ratio;
unsigned long background;
unsigned long dirty;
unsigned long available_memory = determine_dirtyable_memory();
struct task_struct *tsk;
- dirty_ratio = vm_dirty_ratio;
- if (dirty_ratio < 5)
- dirty_ratio = 5;
+ if (vm_dirty_bytes)
+ dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE);
+ else {
+ int dirty_ratio;
- background_ratio = dirty_background_ratio;
- if (background_ratio >= dirty_ratio)
- background_ratio = dirty_ratio / 2;
+ dirty_ratio = vm_dirty_ratio;
+ if (dirty_ratio < 5)
+ dirty_ratio = 5;
+ dirty = (dirty_ratio * available_memory) / 100;
+ }
+
+ if (dirty_background_bytes)
+ background = DIV_ROUND_UP(dirty_background_bytes, PAGE_SIZE);
+ else
+ background = (dirty_background_ratio * available_memory) / 100;
- background = (background_ratio * available_memory) / 100;
- dirty = (dirty_ratio * available_memory) / 100;
+ if (background >= dirty)
+ background = dirty / 2;
tsk = current;
if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) {
background += background / 4;