Commit 8da10cce authored by Javier González's avatar Javier González Committed by Jens Axboe

lightnvm: pblk: avoid being reported as hung on rated GC

The amount of GC I/O on the write buffer is managed by the rate-limiter,
which is calculated as a function of the number of available free
blocks. When reaching the stable point, we risk having scheduled more
I/Os for GC than are allowed on the write buffer. This would result on
the GC semaphore balancing the outstanding read GC I/Os to be reported
as "hung", though the behavior is normal.

Solve this by allowing to schedule when we detect that the read GC path
is not moving forward.
Signed-off-by: default avatarJavier González <javier@cnexlabs.com>
Signed-off-by: default avatarMatias Bjørling <m@bjorling.me>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 8bd40020
...@@ -218,7 +218,13 @@ static void pblk_gc_line_prepare_ws(struct work_struct *work) ...@@ -218,7 +218,13 @@ static void pblk_gc_line_prepare_ws(struct work_struct *work)
gc_rq_ws->line = line; gc_rq_ws->line = line;
gc_rq_ws->priv = gc_rq; gc_rq_ws->priv = gc_rq;
down(&gc->gc_sem); /* The write GC path can be much slower than the read GC one due to
* the budget imposed by the rate-limiter. Balance in case that we get
* back pressure from the write GC path.
*/
while (down_timeout(&gc->gc_sem, msecs_to_jiffies(30000)))
io_schedule();
kref_get(&line->ref); kref_get(&line->ref);
INIT_WORK(&gc_rq_ws->ws, pblk_gc_line_ws); INIT_WORK(&gc_rq_ws->ws, pblk_gc_line_ws);
......
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