From 8da10cce7c7f7f9f5edc77271cf6e0c45b762004 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Javier=20Gonz=C3=A1lez?= Date: Fri, 13 Oct 2017 14:46:45 +0200 Subject: [PATCH] lightnvm: pblk: avoid being reported as hung on rated GC MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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: Javier González Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe --- drivers/lightnvm/pblk-gc.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/lightnvm/pblk-gc.c b/drivers/lightnvm/pblk-gc.c index b8323e34d1bc..00d5698d64a9 100644 --- a/drivers/lightnvm/pblk-gc.c +++ b/drivers/lightnvm/pblk-gc.c @@ -218,7 +218,13 @@ next_rq: gc_rq_ws->line = line; 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); INIT_WORK(&gc_rq_ws->ws, pblk_gc_line_ws); -- 2.30.2