Commit d45ebd47 authored Jun 26, 2017 by Javier González Committed by Jens Axboe Jun 26, 2017

lightnvm: pblk: choose optimal victim GC line



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>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent dffdd960

drivers/lightnvm/pblk-gc.c

+15 −1

Original line number	Diff line number	Diff line
		@@ -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 @@ next_gc_group:
		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);

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