This patch modifies get_dirty_limits() to calculate the limit of dirty
pages based on vm.dirty_limit_ratio. It also changes the interface of the
function to return it.
If mapped memory become large and limit_ratio (calculated based on
vm.dirty_limit_ratio) is decreased, dirty_ratio is also decreased to
keep writeback independently among disks.
Signed-off-by: Tomoki Sekiyama <[email protected]>
Signed-off-by: Yuji Kakutani <[email protected]>
---
mm/page-writeback.c | 37 +++++++++++++++++++++++++++++--------
1 file changed, 29 insertions(+), 8 deletions(-)
Index: linux-2.6.20-mm2-bdp/mm/page-writeback.c
===================================================================
--- linux-2.6.20-mm2-bdp.orig/mm/page-writeback.c
+++ linux-2.6.20-mm2-bdp/mm/page-writeback.c
@@ -117,6 +117,9 @@ static void background_writeout(unsigned
* performing lots of scanning.
*
* We only allow 1/2 of the currently-unmapped memory to be dirtied.
+ * `dirty_limit_ratio' is ignored if it is larger than that.
+ * In this case, `dirty_ratio' is decreased to keep writeback independently
+ * among disks.
*
* We don't permit the clamping level to fall below 5% - that is getting rather
* excessive.
@@ -163,14 +166,16 @@ static unsigned long determine_dirtyable
}
static void
-get_dirty_limits(long *pbackground, long *pdirty,
+get_dirty_limits(long *pbackground, long *pdirty, long *plimit,
struct address_space *mapping)
{
int background_ratio; /* Percentages */
int dirty_ratio;
+ int limit_ratio;
int unmapped_ratio;
long background;
long dirty;
+ long limit;
unsigned long available_memory = determine_dirtyable_memory();
struct task_struct *tsk;
@@ -178,10 +183,17 @@ get_dirty_limits(long *pbackground, long
global_page_state(NR_ANON_PAGES)) * 100) /
available_memory;
+ limit_ratio = dirty_limit_ratio;
+ if (limit_ratio > unmapped_ratio / 2)
+ limit_ratio = unmapped_ratio / 2;
+
dirty_ratio = vm_dirty_ratio;
- if (dirty_ratio > unmapped_ratio / 2)
- dirty_ratio = unmapped_ratio / 2;
+ if (dirty_ratio > dirty_limit_ratio)
+ dirty_ratio = dirty_limit_ratio;
+ dirty_ratio -= dirty_limit_ratio - limit_ratio;
+ if (dirty_limit_ratio < 5)
+ dirty_limit_ratio = 5;
if (dirty_ratio < 5)
dirty_ratio = 5;
@@ -191,13 +203,16 @@ get_dirty_limits(long *pbackground, long
background = (background_ratio * available_memory) / 100;
dirty = (dirty_ratio * available_memory) / 100;
+ limit = (limit_ratio * available_memory) / 100;
tsk = current;
if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) {
background += background / 4;
dirty += dirty / 4;
+ limit += limit / 4;
}
*pbackground = background;
*pdirty = dirty;
+ *plimit = limit;
}
/*
@@ -212,6 +227,7 @@ static void balance_dirty_pages(struct a
long nr_reclaimable;
long background_thresh;
long dirty_thresh;
+ long dirty_limit;
unsigned long pages_written = 0;
unsigned long write_chunk = sync_writeback_pages();
@@ -226,7 +242,8 @@ static void balance_dirty_pages(struct a
.range_cyclic = 1,
};
- get_dirty_limits(&background_thresh, &dirty_thresh, mapping);
+ get_dirty_limits(&background_thresh, &dirty_thresh,
+ &dirty_limit, mapping);
nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS);
if (nr_reclaimable + global_page_state(NR_WRITEBACK) <=
@@ -244,8 +261,8 @@ static void balance_dirty_pages(struct a
*/
if (nr_reclaimable) {
writeback_inodes(&wbc);
- get_dirty_limits(&background_thresh,
- &dirty_thresh, mapping);
+ get_dirty_limits(&background_thresh, &dirty_thresh,
+ &dirty_limit, mapping);
nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS);
if (nr_reclaimable +
@@ -335,9 +352,11 @@ void throttle_vm_writeout(void)
{
long background_thresh;
long dirty_thresh;
+ long dirty_limit;
for ( ; ; ) {
- get_dirty_limits(&background_thresh, &dirty_thresh, NULL);
+ get_dirty_limits(&background_thresh, &dirty_thresh,
+ &dirty_limit, NULL);
/*
* Boost the allowable dirty threshold a bit for page
@@ -372,8 +391,10 @@ static void background_writeout(unsigned
for ( ; ; ) {
long background_thresh;
long dirty_thresh;
+ long dirty_limit;
- get_dirty_limits(&background_thresh, &dirty_thresh, NULL);
+ get_dirty_limits(&background_thresh, &dirty_thresh,
+ &dirty_limit, NULL);
if (global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS) < background_thresh
&& min_pages <= 0)
-
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