lightnvm: pblk: handle case when mw_cunits equals to 0 (ffc03fb7) · Commits · 戴 / test

Some devices can expose mw_cunits equal to 0, it can cause the creation of too small write buffer and cause performance to drop on write workloads. Additionally, write buffer size must cover write data requirements, such as WS_MIN and MW_CUNITS - it must be greater than or equal to the larger one multiplied by the number of PUs. However, for performance reasons, use the WS_OPT value to calculation instead of WS_MIN. Because the place where buffer size is calculated was changed, this patch also removes pgs_in_buffer filed in pblk structure. Signed-off-by:

Marcin Dziegielewski <marcin.dziegielewski@intel.com> Signed-off-by:

Igor Konopko <igor.j.konopko@intel.com> Reviewed-by:

Javier González <javier@cnexlabs.com> Signed-off-by:

Matias Bjørling <mb@lightnvm.io> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

drivers/lightnvm/pblk-init.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -179,11 +179,14 @@ static int pblk_rwb_init(struct pblk *pblk)
		struct pblk_rb_entry *entries;
		unsigned long nr_entries, buffer_size;
		unsigned int power_size, power_seg_sz;
		int pgs_in_buffer;

		if (write_buffer_size && (write_buffer_size > pblk->pgs_in_buffer))
		pgs_in_buffer = max(geo->mw_cunits, geo->ws_opt) * geo->all_luns;

		if (write_buffer_size && (write_buffer_size > pgs_in_buffer))
		buffer_size = write_buffer_size;
		else
		buffer_size = pblk->pgs_in_buffer;
		buffer_size = pgs_in_buffer;

		nr_entries = pblk_rb_calculate_size(buffer_size);

		@@ -366,8 +369,6 @@ static int pblk_core_init(struct pblk *pblk)
		atomic64_set(&pblk->nr_flush, 0);
		pblk->nr_flush_rst = 0;

		pblk->pgs_in_buffer = geo->mw_cunits * geo->all_luns;

		pblk->min_write_pgs = geo->ws_opt * (geo->csecs / PAGE_SIZE);
		max_write_ppas = pblk->min_write_pgs * geo->all_luns;
		pblk->max_write_pgs = min_t(int, max_write_ppas, NVM_MAX_VLBA);

drivers/lightnvm/pblk.h

+0 −3

Original line number	Diff line number	Diff line
		@@ -608,9 +608,6 @@ struct pblk {

		int min_write_pgs; /* Minimum amount of pages required by controller */
		int max_write_pgs; /* Maximum amount of pages supported by controller */
		int pgs_in_buffer; /* Number of pages that need to be held in buffer to
		* guarantee successful reads.
		*/

		sector_t capacity; /* Device capacity when bad blocks are subtracted */

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