> On 7 Jun 2018, at 18.15, Marcin Dziegielewski <marcin.dziegielewski@xxxxxxxxx> wrote:
>
> 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 openchannel write data requirements, such as WS_MIN and MW_CUNITS - it must be greater than or equal to the larger one multipled by number of luns. However, for the performance reason, we are using 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.
Please keep 72 characters on the commit description.
scripts/checkpatch.pl should report this.
Maybe Matias can format it when picking it up.
>
> Signed-off-by: Marcin Dziegielewski <marcin.dziegielewski@xxxxxxxxx>
> Signed-off-by: Igor Konopko <igor.j.konopko@xxxxxxxxx>
> ---
> drivers/lightnvm/pblk-init.c | 9 +++++----
> drivers/lightnvm/pblk.h | 3 ---
> 2 files changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c
> index a27b28d..2f94832 100644
> --- a/drivers/lightnvm/pblk-init.c
> +++ b/drivers/lightnvm/pblk-init.c
> @@ -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);
> diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
> index 7fbdfdc..b62fc3e 100644
> --- a/drivers/lightnvm/pblk.h
> +++ b/drivers/lightnvm/pblk.h
> @@ -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 */
>
> --
> 1.8.3.1
Otherwise the patch looks good.
Reviewed-by: Javier González <javier@xxxxxxxxxxxx>
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