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Message-Id: <1420579582-8516-18-git-send-email-tj@kernel.org>
Date: Tue, 6 Jan 2015 16:25:54 -0500
From: Tejun Heo <tj@...nel.org>
To: axboe@...nel.dk
Cc: linux-kernel@...r.kernel.org, jack@...e.cz, hch@...radead.org,
hannes@...xchg.org, linux-fsdevel@...r.kernel.org,
vgoyal@...hat.com, lizefan@...wei.com, cgroups@...r.kernel.org,
linux-mm@...ck.org, mhocko@...e.cz, clm@...com,
fengguang.wu@...el.com, david@...morbit.com,
Tejun Heo <tj@...nel.org>
Subject: [PATCH 17/45] writeback: make bdi->min/max_ratio handling cgroup writeback aware
bdi->min/max_ratio are user-configurable per-bdi knobs which regulate
dirty limit of each bdi. For cgroup writeback, they need to be
further distributed across wb's (bdi_writeback's) belonging to the
configured bdi.
This patch introduces wb_min_max_ratio() which distributes
bdi->min/max_ratio according to a wb's proportion in the total active
bandwidth of its bdi.
Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: Jens Axboe <axboe@...nel.dk>
Cc: Jan Kara <jack@...e.cz>
---
mm/page-writeback.c | 46 ++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 42 insertions(+), 4 deletions(-)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index cc0ce70..e1b74d7 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -155,6 +155,42 @@ static unsigned long writeout_period_time = 0;
*/
#define VM_COMPLETIONS_PERIOD_LEN (3*HZ)
+#ifdef CONFIG_CGROUP_WRITEBACK
+
+static void wb_min_max_ratio(struct bdi_writeback *wb,
+ unsigned long *minp, unsigned long *maxp)
+{
+ unsigned long this_bw = wb->avg_write_bandwidth;
+ unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth);
+ unsigned long long min = wb->bdi->min_ratio;
+ unsigned long long max = wb->bdi->min_ratio;
+
+ /*
+ * @wb may already be clean by the time control reaches here and
+ * the total may not include its bw.
+ */
+ if (this_bw < tot_bw) {
+ min *= this_bw;
+ max *= this_bw;
+ do_div(min, tot_bw);
+ do_div(max, tot_bw);
+ }
+
+ *minp = min;
+ *maxp = max;
+}
+
+#else /* CONFIG_CGROUP_WRITEBACK */
+
+static void wb_min_max_ratio(struct bdi_writeback *wb,
+ unsigned long *minp, unsigned long *maxp)
+{
+ *minp = wb->bdi->min_ratio;
+ *maxp = wb->bdi->max_ratio;
+}
+
+#endif /* CONFIG_CGROUP_WRITEBACK */
+
/*
* In a memory zone, there is a certain amount of pages we consider
* available for the page cache, which is essentially the number of
@@ -539,9 +575,9 @@ static unsigned long hard_dirty_limit(unsigned long thresh)
*/
unsigned long wb_dirty_limit(struct bdi_writeback *wb, unsigned long dirty)
{
- struct backing_dev_info *bdi = wb->bdi;
u64 wb_dirty;
long numerator, denominator;
+ unsigned long wb_min_ratio, wb_max_ratio;
/*
* Calculate this BDI's share of the dirty ratio.
@@ -552,9 +588,11 @@ unsigned long wb_dirty_limit(struct bdi_writeback *wb, unsigned long dirty)
wb_dirty *= numerator;
do_div(wb_dirty, denominator);
- wb_dirty += (dirty * bdi->min_ratio) / 100;
- if (wb_dirty > (dirty * bdi->max_ratio) / 100)
- wb_dirty = dirty * bdi->max_ratio / 100;
+ wb_min_max_ratio(wb, &wb_min_ratio, &wb_max_ratio);
+
+ wb_dirty += (dirty * wb_min_ratio) / 100;
+ if (wb_dirty > (dirty * wb_max_ratio) / 100)
+ wb_dirty = dirty * wb_max_ratio / 100;
return wb_dirty;
}
--
2.1.0
--
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