Hi Daejun Nice to see your patch, I just run it on my testing workspace, work. and in the next days, I can help you review your patch. Thanks, Bean On Fri, 2020-06-05 at 10:16 +0900, Daejun Park wrote: > 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, we propose 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 "5.8/scsi-queue" branch. > > [1]: > https://www.usenix.org/conference/hotstorage17/program/presentation/jeong > > 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 | 8 + > drivers/scsi/ufs/Makefile | 3 +- > drivers/scsi/ufs/ufs.h | 11 + > drivers/scsi/ufs/ufsfeature.c | 178 ++++ > drivers/scsi/ufs/ufsfeature.h | 95 ++ > drivers/scsi/ufs/ufshcd.c | 19 + > drivers/scsi/ufs/ufshcd.h | 3 + > drivers/scsi/ufs/ufshpb.c | 2029 > +++++++++++++++++++++++++++++++++++++++++ > drivers/scsi/ufs/ufshpb.h | 257 ++++++ > 9 files changed, 2602 insertions(+), 1 deletion(-) > 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
