RE: [RFC PATCH v3 0/5] scsi: ufs: Add Host Performance Booster Support

[Avri Altman <Avri.Altman@wdc.com>]

If no-one else objects, maybe you can submit your patches as non-RFC for review?

Thanks,
Avri

> -----Original Message-----
> From: Daejun Park <daejun7.park@samsung.com>
> Sent: Tuesday, June 23, 2020 4:02 AM
> To: Avri Altman <Avri.Altman@wdc.com>; jejb@linux.ibm.com;
> martin.petersen@oracle.com; asutoshd@codeaurora.org;
> stanley.chu@mediatek.com; cang@codeaurora.org; huobean@gmail.com;
> bvanassche@acm.org; tomas.winkler@intel.com; ALIM AKHTAR
> <alim.akhtar@samsung.com>; Daejun Park <daejun7.park@samsung.com>
> Cc: linux-scsi@vger.kernel.org; linux-kernel@vger.kernel.org; Sang-yoon Oh
> <sangyoon.oh@samsung.com>; Sung-Jun Park
> <sungjun07.park@samsung.com>; yongmyung lee
> <ymhungry.lee@samsung.com>; Jinyoung CHOI <j-
> young.choi@samsung.com>; Adel Choi <adel.choi@samsung.com>; BoRam
> Shin <boram.shin@samsung.com>
> Subject: [RFC PATCH v3 0/5] scsi: ufs: Add Host Performance Booster Support
> 
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> 
> 
> Changelog:
> 
> v2 -> v3
> 1. Add checking input module parameter value.
> 2. Change base commit from 5.8/scsi-queue to 5.9/scsi-queue.
> 3. Cleanup for unused variables and label.
> 
> v1 -> v2
> 1. Change the full boilerplate text to SPDX style.
> 2. Adopt dynamic allocation for sub-region data structure.
> 3. Cleanup.
> 
> NAND flash memory-based storage devices use Flash Translation Layer (FTL)
> to translate logical addresses of I/O requests to corresponding flash
> memory addresses. Mobile storage devices typically have RAM with
> constrained size, thus lack in memory to keep the whole mapping table.
> Therefore, mapping tables are partially retrieved from NAND flash on
> demand, causing random-read performance degradation.
> 
> To improve random read performance, JESD220-3 (HPB v1.0) proposes HPB
> (Host Performance Booster) which uses host system memory as a cache for
> the
> FTL mapping table. By using HPB, FTL data can be read from host memory
> faster than from NAND flash memory.
> 
> The current version only supports the DCM (device control mode).
> This patch consists of 4 parts to support HPB feature.
> 
> 1) UFS-feature layer
> 2) HPB probe and initialization process
> 3) READ -> HPB READ using cached map information
> 4) L2P (logical to physical) map management
> 
> The UFS-feature is an additional layer to avoid the structure in which the
> UFS-core driver and the UFS-feature are entangled with each other in a
> single module.
> By adding the layer, UFS-features composed of various combinations can be
> supported. Also, even if a new feature is added, modification of the
> UFS-core driver can be minimized.
> 
> In the HPB probe and init process, the device information of the UFS is
> queried. After checking supported features, the data structure for the HPB
> is initialized according to the device information.
> 
> A read I/O in the active sub-region where the map is cached is changed to
> HPB READ by the HPB module.
> 
> The HPB module manages the L2P map using information received from the
> device. For active sub-region, the HPB module caches through ufshpb_map
> request. For the in-active region, the HPB module discards the L2P map.
> When a write I/O occurs in an active sub-region area, associated dirty
> bitmap checked as dirty for preventing stale read.
> 
> HPB is shown to have a performance improvement of 58 - 67% for random
> read
> workload. [1]
> 
> This series patches are based on the 5.9/scsi-queue branch.
> 
> [1]:
> https://www.usenix.org/conference/hotstorage17/program/presentation/jeo
> ng
> 
> Daejun park (5):
>  scsi: ufs: Add UFS feature related parameter
>  scsi: ufs: Add UFS feature layer
>  scsi: ufs: Introduce HPB module
>  scsi: ufs: L2P map management for HPB read
>  scsi: ufs: Prepare HPB read for cached sub-region
> 
>  drivers/scsi/ufs/Kconfig      |    9 +
>  drivers/scsi/ufs/Makefile     |    3 +-
>  drivers/scsi/ufs/ufs.h        |   12 +
>  drivers/scsi/ufs/ufsfeature.c |  148 +++
>  drivers/scsi/ufs/ufsfeature.h |   69 ++
>  drivers/scsi/ufs/ufshcd.c     |   23 +-
>  drivers/scsi/ufs/ufshcd.h     |    3 +
>  drivers/scsi/ufs/ufshpb.c     | 1996 ++++++++++++++++++++++++++++++++++++
>  drivers/scsi/ufs/ufshpb.h     |  234 +++++
>  9 files changed, 2494 insertions(+), 3 deletions(-)
>  created mode 100644 drivers/scsi/ufs/ufsfeature.c
>  created mode 100644 drivers/scsi/ufs/ufsfeature.h
>  created mode 100644 drivers/scsi/ufs/ufshpb.c
>  created mode 100644 drivers/scsi/ufs/ufshpb.h