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Groups > linux.kernel > #1674598

[PATCH 14/20] lightnvm: pblk: choose optimal victim GC line

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At the moment, we separate the closed lines on three different list
based on their number of valid sectors. GC recycles lines from each list
based on capacity. Lines from each list are taken in a FIFO fashion.

Since the number of lines is limited (it corresponds to the number of
blocks in a LUN, which is somewhere between 1000-2000), we can afford
scanning the lists to choose the optimal line to be recycled. This helps
specially in lines with a high number of valid sectors.

If the number of blocks per LUN increases, we will consider a more
efficient policy.

Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <matias@cnexlabs.com>
---
 drivers/lightnvm/pblk-gc.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/lightnvm/pblk-gc.c b/drivers/lightnvm/pblk-gc.c
index 2e7fb7a51854..f811e4ca63f4 100644
--- a/drivers/lightnvm/pblk-gc.c
+++ b/drivers/lightnvm/pblk-gc.c
@@ -287,6 +287,20 @@ static void pblk_gc_lines(struct pblk *pblk, struct list_head *gc_list)
 	}
 }
 
+static struct pblk_line *pblk_gc_get_victim_line(struct pblk *pblk,
+						 struct list_head *group_list)
+{
+	struct pblk_line *line, *victim;
+
+	victim = list_first_entry(group_list, struct pblk_line, list);
+	list_for_each_entry(line, group_list, list) {
+		if (*line->vsc < *victim->vsc)
+			victim = line;
+	}
+
+	return victim;
+}
+
 /*
  * Lines with no valid sectors will be returned to the free list immediately. If
  * GC is activated - either because the free block count is under the determined
@@ -332,7 +346,7 @@ static void pblk_gc_run(struct pblk *pblk)
 			return;
 		}
 
-		line = list_first_entry(group_list, struct pblk_line, list);
+		line = pblk_gc_get_victim_line(pblk, group_list);
 		nr_blocks_free += atomic_read(&line->blk_in_line);
 
 		spin_lock(&line->lock);
-- 
2.7.4

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[PATCH 00/20] LightNVM: pblk patches for 4.13 "Javier González" <jg@lightnvm.io> - 2017-06-26 12:00 +0200
  [PATCH 04/20] lightnvm: pblk: add debug stat for read cache hits "Javier González" <jg@lightnvm.io> - 2017-06-26 12:00 +0200
  [PATCH 02/20] lightnvm: propagate right error code to target "Javier González" <jg@lightnvm.io> - 2017-06-26 12:00 +0200
  [PATCH 14/20] lightnvm: pblk: choose optimal victim GC line "Javier González" <jg@lightnvm.io> - 2017-06-26 12:10 +0200
  [PATCH 17/20] lightnvm: pblk: add lock assertions on helpers "Javier González" <jg@lightnvm.io> - 2017-06-26 12:10 +0200
  [PATCH 15/20] lightnvm: pblk: set metadata list for all I/Os "Javier González" <jg@lightnvm.io> - 2017-06-26 12:10 +0200
  [PATCH 01/20] lightnvm: re-convert ppa format on I/O failure "Javier González" <jg@lightnvm.io> - 2017-06-26 12:10 +0200
  [PATCH 13/20] lightnvm: pblk: decouple bad block from line alloc "Javier González" <jg@lightnvm.io> - 2017-06-26 12:10 +0200
  [PATCH 11/20] lightnvm: pblk: issue multiplane reads if possible "Javier González" <jg@lightnvm.io> - 2017-06-26 12:10 +0200
  [PATCH 06/20] lightnvm: pblk: generalize erase path "Javier González" <jg@lightnvm.io> - 2017-06-26 12:10 +0200
  [PATCH 19/20] lightnvm: pblk: set mempool and workqueue params. "Javier González" <jg@lightnvm.io> - 2017-06-26 12:10 +0200
  [PATCH 16/20] lightnvm: pblk: cleanup unnecessary code "Javier González" <jg@lightnvm.io> - 2017-06-26 12:10 +0200
  [PATCH 18/20] lightnvm: pblk: redesign GC algorithm "Javier González" <jg@lightnvm.io> - 2017-06-26 12:10 +0200
  [PATCH 12/20] lightnvm: pblk: simplify meta. memory allocation "Javier González" <jg@lightnvm.io> - 2017-06-26 12:10 +0200
  [PATCH 20/20] lightnvm: pblk: fail gracefully on irrec. error "Javier González" <jg@lightnvm.io> - 2017-06-26 12:10 +0200
  Re: [PATCH 00/20] LightNVM: pblk patches for 4.13 Jens Axboe <axboe@kernel.dk> - 2017-06-27 00:30 +0200
    Re: [PATCH 00/20] LightNVM: pblk patches for 4.13 Javier González <jg@lightnvm.io> - 2017-06-27 10:10 +0200

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