[PATCH] NVMe: increase depth of admin queue

[J Freyensee]

On Fri, 2015-03-06 at 12:56 -0700, Jens Axboe wrote:
> Hi,
> 
> Usually the admin queue depth of 64 is plenty, but for some use cases we
> really need it larger. Examples are use cases like MAT, where you have
> to touch all of NAND for init/format like purposes. In those cases, we
> see a good 2x increase with an increased queue depth.
> 
> Signed-off-by: Jens Axboe <axboe at fb.com>
> 
> diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
> index ceb32dd52a6c..b67b520e489d 100644
> --- a/drivers/block/nvme-core.c
> +++ b/drivers/block/nvme-core.c
> @@ -44,7 +44,7 @@
>  
>  #define NVME_MINORS		(1U << MINORBITS)
>  #define NVME_Q_DEPTH		1024
> -#define NVME_AQ_DEPTH		64
> +#define NVME_AQ_DEPTH		256

Would this be better served to have it be a module parameter so someone
can change it to/from 64 to whatever depth they think they need for
their targeted system and workload?


>  #define SQ_SIZE(depth)		(depth * sizeof(struct nvme_command))
>  #define CQ_SIZE(depth)		(depth * sizeof(struct nvme_completion))
>  #define ADMIN_TIMEOUT		(admin_timeout * HZ)
>