RE: Re: [PATCH v7 0/4] scsi: ufs: Add Host Performance Booster Support

[Daejun Park <daejun7.park@samsung.com>]

Hi Can Guo,
> 
> On 2020-08-05 11:37, Daejun Park wrote:
> > Changelog:
> > 
> > v6 -> v7
> > 1. Remove UFS feature layer.
> > 2. Cleanup for sparse error.
> > 
> > v5 -> v6
> > Change base commit to b53293fa662e28ae0cdd40828dc641c09f133405
> > 
> > v4 -> v5
> > Delete unused macro define.
> > 
> > v3 -> v4
> > 1. Cleanup.
> > 
> > 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 3 parts to support HPB feature.
> > 
> > 1) HPB probe and initialization process
> > 2) READ -> HPB READ using cached map information
> > 3) L2P (logical to physical) map management
> > 
> > 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.
> > 
> > The HPB manages the L2P map using information received from the
> > device. For active sub-region, the HPB caches through ufshpb_map
> > request. For the in-active region, the HPB 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/jeong
> > 
> > Daejun park (4):
> >  scsi: ufs: Add UFS feature related parameter
> >  scsi: ufs: Introduce HPB feature
> >  scsi: ufs: L2P map management for HPB read
> >  scsi: ufs: Prepare HPB read for cached sub-region
> > 
> >  drivers/scsi/ufs/Kconfig  |   18 +
> >  drivers/scsi/ufs/Makefile |    1 +
> >  drivers/scsi/ufs/ufs.h    |   12 +
> >  drivers/scsi/ufs/ufshcd.c |   42 +
> >  drivers/scsi/ufs/ufshcd.h |    9 +
> >  drivers/scsi/ufs/ufshpb.c | 1926 
> > ++++++++++++++++++++++++++++++++++++++++
> >  drivers/scsi/ufs/ufshpb.h |  241 +++++
> >  7 files changed, 2249 insertions(+)
> >  created mode 100644 drivers/scsi/ufs/ufshpb.c
> >  created mode 100644 drivers/scsi/ufs/ufshpb.h
> 
> I only gave my reviewed-by tag to the very first patch (changes to 
> ufshcd.h),
> but not the whole series. Please remove those tags accordingly.
> 
OK, I am sorry about that.
I will remove tags and re-submit my patches.

Thanks,

Daejun