Commit 3bcebc5b authored by Hans Holmberg's avatar Hans Holmberg Committed by Jens Axboe
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lightnvm: pblk: set conservative threshold for user writes 



In a worst-case scenario (random writes), OP% of sectors
in each line will be invalid, and we will then need
to move data out of 100/OP% lines to free a single line.

So, to prevent the possibility of running out of lines,
temporarily block user writes when there is less than
100/OP% free lines.

Also ensure that pblk creation does not produce instances
with insufficient over provisioning.

Insufficient over-provising is not a problem on real hardware,
but often an issue when running QEMU simulations (with few lines).
100 lines is enough to create a sane instance with the standard
(11%) over provisioning.

Signed-off-by: default avatarHans Holmberg <hans.holmberg@cnexlabs.com>
Reviewed-by: default avatarJavier González <javier@javigon.com>
Signed-off-by: default avatarMatias Bjørling <mb@lightnvm.io>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 525f7bb2

drivers/lightnvm/pblk-init.c

+31 −9
Original line number Original line Diff line number Diff line
@@ -635,7 +635,7 @@ static unsigned int calc_emeta_len(struct pblk *pblk) 
	return (lm->emeta_len[1] + lm->emeta_len[2] + lm->emeta_len[3]);

	return (lm->emeta_len[1] + lm->emeta_len[2] + lm->emeta_len[3]);

}

}





static void pblk_set_provision(struct pblk *pblk, long nr_free_blks)

static int pblk_set_provision(struct pblk *pblk, int nr_free_chks)

{

{

	struct nvm_tgt_dev *dev = pblk->dev;

	struct nvm_tgt_dev *dev = pblk->dev;

	struct pblk_line_mgmt *l_mg = &pblk->l_mg;

	struct pblk_line_mgmt *l_mg = &pblk->l_mg;
@@ -643,23 +643,41 @@ static void pblk_set_provision(struct pblk *pblk, long nr_free_blks) 
	struct nvm_geo *geo = &dev->geo;

	struct nvm_geo *geo = &dev->geo;

	sector_t provisioned;

	sector_t provisioned;

	int sec_meta, blk_meta;

	int sec_meta, blk_meta;

	int minimum;





	if (geo->op == NVM_TARGET_DEFAULT_OP)

	if (geo->op == NVM_TARGET_DEFAULT_OP)

		pblk->op = PBLK_DEFAULT_OP;

		pblk->op = PBLK_DEFAULT_OP;

	else

	else

		pblk->op = geo->op;

		pblk->op = geo->op;





	provisioned = nr_free_blks;

	minimum = pblk_get_min_chks(pblk);

	provisioned = nr_free_chks;

	provisioned *= (100 - pblk->op);

	provisioned *= (100 - pblk->op);

	sector_div(provisioned, 100);

	sector_div(provisioned, 100);





	pblk->op_blks = nr_free_blks - provisioned;

	if ((nr_free_chks - provisioned) < minimum) {

		if (geo->op != NVM_TARGET_DEFAULT_OP) {

			pblk_err(pblk, "OP too small to create a sane instance\n");

			return -EINTR;

		}



		/* If the user did not specify an OP value, and PBLK_DEFAULT_OP

		 * is not enough, calculate and set sane value

		 */



		provisioned = nr_free_chks - minimum;

		pblk->op =  (100 * minimum) / nr_free_chks;

		pblk_info(pblk, "Default OP insufficient, adjusting OP to %d\n",

				pblk->op);

	}



	pblk->op_blks = nr_free_chks - provisioned;





	/* Internally pblk manages all free blocks, but all calculations based

	/* Internally pblk manages all free blocks, but all calculations based

	 * on user capacity consider only provisioned blocks

	 * on user capacity consider only provisioned blocks

	 */

	 */

	pblk->rl.total_blocks = nr_free_blks;

	pblk->rl.total_blocks = nr_free_chks;

	pblk->rl.nr_secs = nr_free_blks * geo->clba;

	pblk->rl.nr_secs = nr_free_chks * geo->clba;





	/* Consider sectors used for metadata */

	/* Consider sectors used for metadata */

	sec_meta = (lm->smeta_sec + lm->emeta_sec[0]) * l_mg->nr_free_lines;

	sec_meta = (lm->smeta_sec + lm->emeta_sec[0]) * l_mg->nr_free_lines;
@@ -667,8 +685,10 @@ static void pblk_set_provision(struct pblk *pblk, long nr_free_blks) 




	pblk->capacity = (provisioned - blk_meta) * geo->clba;

	pblk->capacity = (provisioned - blk_meta) * geo->clba;





	atomic_set(&pblk->rl.free_blocks, nr_free_blks);

	atomic_set(&pblk->rl.free_blocks, nr_free_chks);

	atomic_set(&pblk->rl.free_user_blocks, nr_free_blks);

	atomic_set(&pblk->rl.free_user_blocks, nr_free_chks);



	return 0;

}

}





static int pblk_setup_line_meta_chk(struct pblk *pblk, struct pblk_line *line,

static int pblk_setup_line_meta_chk(struct pblk *pblk, struct pblk_line *line,
@@ -984,7 +1004,7 @@ static int pblk_lines_init(struct pblk *pblk) 
	struct pblk_line_mgmt *l_mg = &pblk->l_mg;

	struct pblk_line_mgmt *l_mg = &pblk->l_mg;

	struct pblk_line *line;

	struct pblk_line *line;

	void *chunk_meta;

	void *chunk_meta;

	long nr_free_chks = 0;

	int nr_free_chks = 0;

	int i, ret;

	int i, ret;





	ret = pblk_line_meta_init(pblk);

	ret = pblk_line_meta_init(pblk);
@@ -1031,7 +1051,9 @@ static int pblk_lines_init(struct pblk *pblk) 
		goto fail_free_lines;

		goto fail_free_lines;

	}

	}





	pblk_set_provision(pblk, nr_free_chks);

	ret = pblk_set_provision(pblk, nr_free_chks);

	if (ret)

		goto fail_free_lines;





	vfree(chunk_meta);

	vfree(chunk_meta);

	return 0;

	return 0;

drivers/lightnvm/pblk-rl.c

+2 −3
Original line number Original line Diff line number Diff line
@@ -214,11 +214,10 @@ void pblk_rl_init(struct pblk_rl *rl, int budget) 
	struct nvm_geo *geo = &dev->geo;

	struct nvm_geo *geo = &dev->geo;

	struct pblk_line_mgmt *l_mg = &pblk->l_mg;

	struct pblk_line_mgmt *l_mg = &pblk->l_mg;

	struct pblk_line_meta *lm = &pblk->lm;

	struct pblk_line_meta *lm = &pblk->lm;

	int min_blocks = lm->blk_per_line * PBLK_GC_RSV_LINE;

	int sec_meta, blk_meta;

	int sec_meta, blk_meta;



	unsigned int rb_windows;

	unsigned int rb_windows;







	/* Consider sectors used for metadata */

	/* Consider sectors used for metadata */

	sec_meta = (lm->smeta_sec + lm->emeta_sec[0]) * l_mg->nr_free_lines;

	sec_meta = (lm->smeta_sec + lm->emeta_sec[0]) * l_mg->nr_free_lines;

	blk_meta = DIV_ROUND_UP(sec_meta, geo->clba);

	blk_meta = DIV_ROUND_UP(sec_meta, geo->clba);
@@ -226,7 +225,7 @@ void pblk_rl_init(struct pblk_rl *rl, int budget) 
	rl->high = pblk->op_blks - blk_meta - lm->blk_per_line;

	rl->high = pblk->op_blks - blk_meta - lm->blk_per_line;

	rl->high_pw = get_count_order(rl->high);

	rl->high_pw = get_count_order(rl->high);





	rl->rsv_blocks = min_blocks;

	rl->rsv_blocks = pblk_get_min_chks(pblk);





	/* This will always be a power-of-2 */

	/* This will always be a power-of-2 */

	rb_windows = budget / NVM_MAX_VLBA;

	rb_windows = budget / NVM_MAX_VLBA;

drivers/lightnvm/pblk.h

+11 −1
Original line number Original line Diff line number Diff line
@@ -905,7 +905,6 @@ int pblk_recov_check_emeta(struct pblk *pblk, struct line_emeta *emeta); 
#define PBLK_GC_MAX_READERS 8	/* Max number of outstanding GC reader jobs */

#define PBLK_GC_MAX_READERS 8	/* Max number of outstanding GC reader jobs */

#define PBLK_GC_RQ_QD 128	/* Queue depth for inflight GC requests */

#define PBLK_GC_RQ_QD 128	/* Queue depth for inflight GC requests */

#define PBLK_GC_L_QD 4		/* Queue depth for inflight GC lines */

#define PBLK_GC_L_QD 4		/* Queue depth for inflight GC lines */

#define PBLK_GC_RSV_LINE 1	/* Reserved lines for GC */





int pblk_gc_init(struct pblk *pblk);

int pblk_gc_init(struct pblk *pblk);

void pblk_gc_exit(struct pblk *pblk, bool graceful);

void pblk_gc_exit(struct pblk *pblk, bool graceful);
@@ -1370,4 +1369,15 @@ static inline char *pblk_disk_name(struct pblk *pblk) 




	return disk->disk_name;

	return disk->disk_name;

}

}



static inline unsigned int pblk_get_min_chks(struct pblk *pblk)

{

	struct pblk_line_meta *lm = &pblk->lm;

	/* In a worst-case scenario every line will have OP invalid sectors.

	 * We will then need a minimum of 1/OP lines to free up a single line

	 */



	return DIV_ROUND_UP(100, pblk->op) * lm->blk_per_line;



}

#endif /* PBLK_H_ */
 
#endif /* PBLK_H_ */

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