When the system is under background dirty memory threshold but a cgroup
is over its background dirty memory threshold, then only writeback
inodes associated with the over-limit cgroup(s).
In addition to checking if the system dirty memory usage is over the
system background threshold, over_bground_thresh() also checks if any
cgroups are over their respective background dirty memory thresholds.
The writeback_control.for_cgroup field is set to distinguish between a
system and memcg overage.
If performing cgroup writeback, move_expired_inodes() skips inodes that
do not contribute dirty pages to the cgroup being written back.
After writing some pages, wb_writeback() will call
mem_cgroup_writeback_done() to update the set of over-bg-limits memcg.
Signed-off-by: Greg Thelen <gthelen@xxxxxxxxxx>
---
fs/fs-writeback.c | 31 +++++++++++++++++++++++--------
1 files changed, 23 insertions(+), 8 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 0174fcf..b01bb2a 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -256,14 +256,17 @@ static void move_expired_inodes(struct list_head *delaying_queue,
LIST_HEAD(tmp);
struct list_head *pos, *node;
struct super_block *sb = NULL;
- struct inode *inode;
+ struct inode *inode, *tmp_inode;
int do_sb_sort = 0;
- while (!list_empty(delaying_queue)) {
- inode = wb_inode(delaying_queue->prev);
+ list_for_each_entry_safe_reverse(inode, tmp_inode, delaying_queue,
+ i_wb_list) {
if (wbc->older_than_this &&
inode_dirtied_after(inode, *wbc->older_than_this))
break;
+ if (wbc->for_cgroup &&
+ !should_writeback_mem_cgroup_inode(inode, wbc))
+ continue;
if (sb && sb != inode->i_sb)
do_sb_sort = 1;
sb = inode->i_sb;
@@ -614,14 +617,21 @@ void writeback_inodes_wb(struct bdi_writeback *wb,
*/
#define MAX_WRITEBACK_PAGES 1024
-static inline bool over_bground_thresh(void)
+static inline bool over_bground_thresh(struct bdi_writeback *wb,
+ struct writeback_control *wbc)
{
unsigned long background_thresh, dirty_thresh;
global_dirty_limits(&background_thresh, &dirty_thresh);
- return (global_page_state(NR_FILE_DIRTY) +
- global_page_state(NR_UNSTABLE_NFS) > background_thresh);
+ if (global_page_state(NR_FILE_DIRTY) +
+ global_page_state(NR_UNSTABLE_NFS) > background_thresh) {
+ wbc->for_cgroup = 0;
+ return true;
+ }
+
+ wbc->for_cgroup = 1;
+ return mem_cgroups_over_bground_dirty_thresh();
}
/*
@@ -700,7 +710,7 @@ static long wb_writeback(struct bdi_writeback *wb,
* For background writeout, stop when we are below the
* background dirty threshold
*/
- if (work->for_background && !over_bground_thresh())
+ if (work->for_background && !over_bground_thresh(wb, &wbc))
break;
if (work->for_kupdate || work->for_background) {
@@ -729,6 +739,9 @@ retry:
work->nr_pages -= write_chunk - wbc.nr_to_write;
wrote += write_chunk - wbc.nr_to_write;
+ if (write_chunk - wbc.nr_to_write > 0)
+ mem_cgroup_writeback_done();
+
/*
* Did we write something? Try for more
*
@@ -809,7 +822,9 @@ static unsigned long get_nr_dirty_pages(void)
static long wb_check_background_flush(struct bdi_writeback *wb)
{
- if (over_bground_thresh()) {
+ struct writeback_control wbc;
+
+ if (over_bground_thresh(wb, &wbc)) {
struct wb_writeback_work work = {
.nr_pages = LONG_MAX,
--
1.7.3.1
--
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