If the current process is in a non-root memcg, then
balance_dirty_pages() will consider the memcg dirty limits
as well as the system-wide limits. This allows different
cgroups to have distinct dirty limits which trigger direct
and background writeback at different levels.
Signed-off-by: Andrea Righi <arighi@xxxxxxxxxxx>
Signed-off-by: Greg Thelen <gthelen@xxxxxxxxxx>
---
Changelog since v3:
- Leave determine_dirtyable_memory() static. v3 made is non-static.
- balance_dirty_pages() now considers both system and memcg dirty limits and
usage data. This data is retrieved with global_dirty_info() and
memcg_dirty_info().
mm/page-writeback.c | 109 ++++++++++++++++++++++++++++++++++++--------------
1 files changed, 78 insertions(+), 31 deletions(-)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index b3bb2fb..57caee5 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -131,6 +131,18 @@ EXPORT_SYMBOL(laptop_mode);
static struct prop_descriptor vm_completions;
static struct prop_descriptor vm_dirties;
+static unsigned long dirty_writeback_pages(void)
+{
+ s64 ret;
+
+ ret = mem_cgroup_page_stat(MEMCG_NR_DIRTY_WRITEBACK_PAGES);
+ if (ret < 0)
+ ret = global_page_state(NR_UNSTABLE_NFS) +
+ global_page_state(NR_WRITEBACK);
+
+ return ret;
+}
+
/*
* couple the period to the dirty_ratio:
*
@@ -398,45 +410,67 @@ unsigned long determine_dirtyable_memory(void)
}
/*
+ * The dirty limits will be lifted by 1/4 for PF_LESS_THROTTLE (ie. nfsd) and
+ * runtime tasks.
+ */
+static inline void adjust_dirty_info(struct dirty_info *info)
+{
+ struct task_struct *tsk;
+
+ if (info->background_thresh >= info->dirty_thresh)
+ info->background_thresh = info->dirty_thresh / 2;
+ tsk = current;
+ if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) {
+ info->background_thresh += info->background_thresh / 4;
+ info->dirty_thresh += info->dirty_thresh / 4;
+ }
+}
+
+/*
* global_dirty_info - return background-writeback and dirty-throttling
* thresholds as well as dirty usage metrics.
*
* Calculate the dirty thresholds based on sysctl parameters
* - vm.dirty_background_ratio or vm.dirty_background_bytes
* - vm.dirty_ratio or vm.dirty_bytes
- * The dirty limits will be lifted by 1/4 for PF_LESS_THROTTLE (ie. nfsd) and
- * runtime tasks.
*/
void global_dirty_info(struct dirty_info *info)
{
- unsigned long background;
- unsigned long dirty;
unsigned long available_memory = determine_dirtyable_memory();
- struct task_struct *tsk;
if (vm_dirty_bytes)
- dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE);
+ info->dirty_thresh = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE);
else
- dirty = (vm_dirty_ratio * available_memory) / 100;
+ info->dirty_thresh = (vm_dirty_ratio * available_memory) / 100;
if (dirty_background_bytes)
- background = DIV_ROUND_UP(dirty_background_bytes, PAGE_SIZE);
+ info->background_thresh =
+ DIV_ROUND_UP(dirty_background_bytes, PAGE_SIZE);
else
- background = (dirty_background_ratio * available_memory) / 100;
+ info->background_thresh =
+ (dirty_background_ratio * available_memory) / 100;
info->nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS);
info->nr_writeback = global_page_state(NR_WRITEBACK);
- if (background >= dirty)
- background = dirty / 2;
- tsk = current;
- if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) {
- background += background / 4;
- dirty += dirty / 4;
- }
- info->background_thresh = background;
- info->dirty_thresh = dirty;
+ adjust_dirty_info(info);
+}
+
+/*
+ * Calculate the background-writeback and dirty-throttling thresholds and dirty
+ * usage metrics from the current task's memcg dirty limit parameters. Returns
+ * false if no memcg limits exist.
+ */
+static bool memcg_dirty_info(struct dirty_info *info)
+{
+ unsigned long available_memory = determine_dirtyable_memory();
+
+ if (!mem_cgroup_dirty_info(available_memory, info))
+ return false;
+
+ adjust_dirty_info(info);
+ return true;
}
/*
@@ -480,7 +514,8 @@ unsigned long bdi_dirty_limit(struct backing_dev_info *bdi, unsigned long dirty)
static void balance_dirty_pages(struct address_space *mapping,
unsigned long write_chunk)
{
- struct dirty_info dirty_info;
+ struct dirty_info sys_info;
+ struct dirty_info memcg_info;
long bdi_nr_reclaimable;
long bdi_nr_writeback;
unsigned long bdi_thresh;
@@ -497,19 +532,27 @@ static void balance_dirty_pages(struct address_space *mapping,
.range_cyclic = 1,
};
- global_dirty_info(&dirty_info);
+ global_dirty_info(&sys_info);
+
+ if (!memcg_dirty_info(&memcg_info))
+ memcg_info = sys_info;
/*
* Throttle it only when the background writeback cannot
* catch-up. This avoids (excessively) small writeouts
* when the bdi limits are ramping up.
*/
- if (dirty_info.nr_reclaimable + dirty_info.nr_writeback <=
- (dirty_info.background_thresh +
- dirty_info.dirty_thresh) / 2)
+ if ((sys_info.nr_reclaimable + sys_info.nr_writeback <=
+ (sys_info.background_thresh +
+ sys_info.dirty_thresh) / 2) &&
+ (memcg_info.nr_reclaimable + memcg_info.nr_writeback <=
+ (memcg_info.background_thresh +
+ memcg_info.dirty_thresh) / 2))
break;
- bdi_thresh = bdi_dirty_limit(bdi, dirty_info.dirty_thresh);
+ bdi_thresh = bdi_dirty_limit(bdi,
+ min(sys_info.dirty_thresh,
+ memcg_info.dirty_thresh));
bdi_thresh = task_dirty_limit(current, bdi_thresh);
/*
@@ -538,9 +581,12 @@ static void balance_dirty_pages(struct address_space *mapping,
*/
dirty_exceeded =
(bdi_nr_reclaimable + bdi_nr_writeback > bdi_thresh)
- || (dirty_info.nr_reclaimable +
- dirty_info.nr_writeback >
- dirty_info.dirty_thresh);
+ || (sys_info.nr_reclaimable +
+ sys_info.nr_writeback >
+ sys_info.dirty_thresh)
+ || (memcg_info.nr_reclaimable +
+ memcg_info.nr_writeback >
+ memcg_info.dirty_thresh);
if (!dirty_exceeded)
break;
@@ -593,8 +639,10 @@ static void balance_dirty_pages(struct address_space *mapping,
* background_thresh, to keep the amount of dirty memory low.
*/
if ((laptop_mode && pages_written) ||
- (!laptop_mode && (dirty_info.nr_reclaimable >
- dirty_info.background_thresh)))
+ (!laptop_mode && ((sys_info.nr_reclaimable >
+ sys_info.background_thresh) ||
+ (memcg_info.nr_reclaimable >
+ memcg_info.background_thresh))))
bdi_start_background_writeback(bdi);
}
@@ -666,8 +714,7 @@ void throttle_vm_writeout(gfp_t gfp_mask)
dirty_info.dirty_thresh +=
dirty_info.dirty_thresh / 10; /* wheeee... */
- if (global_page_state(NR_UNSTABLE_NFS) +
- global_page_state(NR_WRITEBACK) <= dirty_info.dirty_thresh)
+ if (dirty_writeback_pages() <= dirty_info.dirty_thresh)
break;
congestion_wait(BLK_RW_ASYNC, HZ/10);
--
1.7.3.1
--
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