Re: [PATCH v3 0/4] Initial support for multi-actuator HDDs

[Damien Le Moal <Damien.LeMoal@wdc.com>]

On 2021/07/26 10:38, Damien Le Moal wrote:
> Single LUN multi-actuator hard-disks are cappable to seek and execute
> multiple commands in parallel. This capability is exposed to the host
> using the Concurrent Positioning Ranges VPD page (SCSI) and Log (ATA).
> Each positioning range describes the contiguous set of LBAs that an
> actuator serves.
> 
> This series adds support the scsi disk driver to retreive this
> information and advertize it to user space through sysfs. libata is also
> modified to handle ATA drives.
> 
> The first patch adds the block layer plumbing to expose concurrent
> sector ranges of the device through sysfs as a sub-directory of the
> device sysfs queue directory. Patch 2 and 3 add support to sd and
> libata. Finally patch 4 documents the sysfs queue attributed changes.
> 
> This series does not attempt in any way to optimize accesses to
> multi-actuator devices (e.g. block IO scheduler or filesystems). This
> initial support only exposes the actuators information to user space
> through sysfs.

Jens, Martin,

Any comment on this series ?

> 
> Changes from v2:
> * Update patch 1 to fix a compilation warning for a potential NULL
>   pointer dereference of the cr argument of blk_queue_set_cranges().
>   Warning reported by the kernel test robot <lkp@intel.com>).
> 
> Changes from v1:
> * Moved libata-scsi hunk from patch 1 to patch 3 where it belongs
> * Fixed unintialized variable in patch 2
>   Reported-by: kernel test robot <lkp@intel.com>
>   Reported-by: Dan Carpenter <dan.carpenter@oracle.com
> * Changed patch 3 adding struct ata_cpr_log to contain both the number
>   of concurrent ranges and the array of concurrent ranges.
> * Added a note in the documentation (patch 4) about the unit used for
>   the concurrent ranges attributes.
> 
> Damien Le Moal (4):
>   block: Add concurrent positioning ranges support
>   scsi: sd: add concurrent positioning ranges support
>   libata: support concurrent positioning ranges log
>   doc: document sysfs queue/cranges attributes
> 
>  Documentation/block/queue-sysfs.rst |  30 ++-
>  block/Makefile                      |   2 +-
>  block/blk-cranges.c                 | 295 ++++++++++++++++++++++++++++
>  block/blk-sysfs.c                   |  13 ++
>  block/blk.h                         |   3 +
>  drivers/ata/libata-core.c           |  52 +++++
>  drivers/ata/libata-scsi.c           |  48 ++++-
>  drivers/scsi/sd.c                   |  81 ++++++++
>  drivers/scsi/sd.h                   |   1 +
>  include/linux/ata.h                 |   1 +
>  include/linux/blkdev.h              |  29 +++
>  include/linux/libata.h              |  15 ++
>  12 files changed, 559 insertions(+), 11 deletions(-)
>  create mode 100644 block/blk-cranges.c
> 


-- 
Damien Le Moal
Western Digital Research