svn commit: r290199 - in head/sys/dev: nvd nvme

[Steven Hartland]

Hi Jim could you let me know the use case for exposing the controller 
stripe size as the disk stripe size done by this commit?

I ask as it actually causes problems for ZFS which has checks to ensure 
zpools perform optimally by correctly configuring ashift to match the 
stripesize if reported.

This is usually fine as stripe size typically reports the physical block 
size of device, where sectorsize is the logical block size, 
unfortunately this is currently limited to ashift of 13 (8KB) so when 
nvme reports 128KB it limits it 8KB and hence every subsequent zpool 
status reports a warning about optimal performance.

Before I look to fix one or the other, I wanted to fully understand the 
reasoning behind how nvme behaves here.

On 30/10/2015 16:35, Jim Harris wrote:
> Author: jimharris
> Date: Fri Oct 30 16:35:18 2015
> New Revision: 290199
> URL: https://svnweb.freebsd.org/changeset/base/290199
>
> Log:
>    nvd, nvme: report stripesize through GEOM disk layer
>    
>    MFC after:	3 days
>    Sponsored by:	Intel
>
> Modified:
>    head/sys/dev/nvd/nvd.c
>    head/sys/dev/nvme/nvme.h
>    head/sys/dev/nvme/nvme_ns.c
>
> Modified: head/sys/dev/nvd/nvd.c
> ==============================================================================
> --- head/sys/dev/nvd/nvd.c	Fri Oct 30 16:06:34 2015	(r290198)
> +++ head/sys/dev/nvd/nvd.c	Fri Oct 30 16:35:18 2015	(r290199)
> @@ -279,6 +279,7 @@ nvd_new_disk(struct nvme_namespace *ns,
>   	disk->d_sectorsize = nvme_ns_get_sector_size(ns);
>   	disk->d_mediasize = (off_t)nvme_ns_get_size(ns);
>   	disk->d_delmaxsize = (off_t)nvme_ns_get_size(ns);
> +	disk->d_stripesize = nvme_ns_get_stripesize(ns);
>   
>   	if (TAILQ_EMPTY(&disk_head))
>   		disk->d_unit = 0;
>
> Modified: head/sys/dev/nvme/nvme.h
> ==============================================================================
> --- head/sys/dev/nvme/nvme.h	Fri Oct 30 16:06:34 2015	(r290198)
> +++ head/sys/dev/nvme/nvme.h	Fri Oct 30 16:35:18 2015	(r290199)
> @@ -870,6 +870,7 @@ const char *	nvme_ns_get_serial_number(s
>   const char *	nvme_ns_get_model_number(struct nvme_namespace *ns);
>   const struct nvme_namespace_data *
>   		nvme_ns_get_data(struct nvme_namespace *ns);
> +uint32_t	nvme_ns_get_stripesize(struct nvme_namespace *ns);
>   
>   int	nvme_ns_bio_process(struct nvme_namespace *ns, struct bio *bp,
>   			    nvme_cb_fn_t cb_fn);
>
> Modified: head/sys/dev/nvme/nvme_ns.c
> ==============================================================================
> --- head/sys/dev/nvme/nvme_ns.c	Fri Oct 30 16:06:34 2015	(r290198)
> +++ head/sys/dev/nvme/nvme_ns.c	Fri Oct 30 16:35:18 2015	(r290199)
> @@ -210,6 +210,13 @@ nvme_ns_get_data(struct nvme_namespace *
>   	return (&ns->data);
>   }
>   
> +uint32_t
> +nvme_ns_get_stripesize(struct nvme_namespace *ns)
> +{
> +
> +	return (ns->stripesize);
> +}
> +
>   static void
>   nvme_ns_bio_done(void *arg, const struct nvme_completion *status)
>   {
>