linux-kernel - Re: [RFC 1/4] lightnvm: precalculate controller write boundaries

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Message-ID: <56B4B76B.6010007@lightnvm.io>
Date:	Fri, 5 Feb 2016 15:53:31 +0100
From:	Matias Bjørling <mb@...htnvm.io>
To:	Javier González <jg@...htnvm.io>
Cc:	linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
	Javier González <javier@...xlabs.com>
Subject: Re: [RFC 1/4] lightnvm: precalculate controller write boundaries

On 02/04/2016 02:08 PM, Javier González wrote:
> Flash controllers typically define flash pages as a collection of flash
> sectors of typically 4K. Moreover, flash controllers might program flash
> pages across several planes. This defines the write granurality at which
> flash can be programmed. This is different for each flash controller.
> 
> In order to simplify calculations, and avoid repeating them in a per-I/O
> basis, this patch pre-calculates write granurality values as part of the
> device characteristics in the bring up.
> 
> Signed-off-by: Javier González <javier@...xlabs.com>
> ---
>  drivers/lightnvm/rrpc.c | 4 ++++
>  drivers/lightnvm/rrpc.h | 3 +++
>  2 files changed, 7 insertions(+)
> 
> diff --git a/drivers/lightnvm/rrpc.c b/drivers/lightnvm/rrpc.c
> index 775bf6c2..8187bf3 100644
> --- a/drivers/lightnvm/rrpc.c
> +++ b/drivers/lightnvm/rrpc.c
> @@ -1149,6 +1149,10 @@ static int rrpc_luns_init(struct rrpc *rrpc, int lun_begin, int lun_end)
>  	if (!rrpc->luns)
>  		return -ENOMEM;
>  
> +	rrpc->min_write_pgs = dev->sec_per_pl * (dev->sec_size / PAGE_SIZE);
> +	/* assume max_phys_sect % dev->min_write_pgs == 0 */
> +	rrpc->max_write_pgs = dev->ops->max_phys_sect;
> +
>  	/* 1:1 mapping */
>  	for (i = 0; i < rrpc->nr_luns; i++) {
>  		struct nvm_lun *lun = dev->mt->get_lun(dev, lun_begin + i);
> diff --git a/drivers/lightnvm/rrpc.h b/drivers/lightnvm/rrpc.h
> index 3989d65..868e91a 100644
> --- a/drivers/lightnvm/rrpc.h
> +++ b/drivers/lightnvm/rrpc.h
> @@ -107,6 +107,9 @@ struct rrpc {
>  	unsigned long long nr_sects;
>  	unsigned long total_blocks;
>  
> +	int min_write_pgs; /* minimum amount of pages required by controller */
> +	int max_write_pgs; /* maximum amount of pages supported by controller */
> +
>  	/* Write strategy variables. Move these into each for structure for each
>  	 * strategy
>  	 */
> 

This belongs to the write buffer patch.