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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>
This commit is contained in:
Joe Thornber 2017-11-08 06:41:43 -05:00 committed by Mike Snitzer
parent deb71918ae
commit 64748b1645
1 changed files with 12 additions and 6 deletions
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18
drivers/md/dm-cache-background-tracker.c
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@ -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;