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authorJoe Thornber <ejt@redhat.com>2017-11-08 06:41:43 -0500
committerMike Snitzer <snitzer@redhat.com>2017-11-10 15:45:03 -0500
commit64748b1645b81399d01ad86657c5bbe097c1701c (patch)
treeaa903c1a0cc40df6b51f61b8a595c897c52f7697
parentdeb71918ae29e23ff7f4537f5ff654f8b6580af2 (diff)
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dm cache background tracker: limit amount of background work that may be issued at once
On large systems the cache policy can be over enthusiastic and queue far too much dirty data to be written back. This consumes memory. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
-rw-r--r--drivers/md/dm-cache-background-tracker.c18
1 files changed, 12 insertions, 6 deletions
diff --git a/drivers/md/dm-cache-background-tracker.c b/drivers/md/dm-cache-background-tracker.c
index 707233891291..1d0af0a21fc7 100644
--- a/drivers/md/dm-cache-background-tracker.c
+++ b/drivers/md/dm-cache-background-tracker.c
@@ -161,8 +161,17 @@ EXPORT_SYMBOL_GPL(btracker_nr_demotions_queued);
static bool max_work_reached(struct background_tracker *b)
{
- // FIXME: finish
- return false;
+ return atomic_read(&b->pending_promotes) +
+ atomic_read(&b->pending_writebacks) +
+ atomic_read(&b->pending_demotes) >= b->max_work;
+}
+
+struct bt_work *alloc_work(struct background_tracker *b)
+{
+ if (max_work_reached(b))
+ return NULL;
+
+ return kmem_cache_alloc(b->work_cache, GFP_NOWAIT);
}
int btracker_queue(struct background_tracker *b,
@@ -174,10 +183,7 @@ int btracker_queue(struct background_tracker *b,
if (pwork)
*pwork = NULL;
- if (max_work_reached(b))
- return -ENOMEM;
-
- w = kmem_cache_alloc(b->work_cache, GFP_NOWAIT);
+ w = alloc_work(b);
if (!w)
return -ENOMEM;