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Subject: RE: [PATCH v11 0/4] scsi: ufs: Add Host Performance Booster Support
Reply-To: daejun7.park@samsung.com
From:   Daejun Park <daejun7.park@samsung.com>
To:     Daejun Park <daejun7.park@samsung.com>,
        "avri.altman@wdc.com" <avri.altman@wdc.com>,
        "jejb@linux.ibm.com" <jejb@linux.ibm.com>,
        "martin.petersen@oracle.com" <martin.petersen@oracle.com>,
        "asutoshd@codeaurora.org" <asutoshd@codeaurora.org>,
        "beanhuo@micron.com" <beanhuo@micron.com>,
        "stanley.chu@mediatek.com" <stanley.chu@mediatek.com>,
        "cang@codeaurora.org" <cang@codeaurora.org>,
        "bvanassche@acm.org" <bvanassche@acm.org>,
        "tomas.winkler@intel.com" <tomas.winkler@intel.com>,
        ALIM AKHTAR <alim.akhtar@samsung.com>
CC:     "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
        "linux-kernel@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>,
        SEUNGUK SHIN <seunguk.shin@samsung.com>
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Date:   Wed, 16 Sep 2020 08:05:17 +0900
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Hi All,

I want to know how to improve this patch.
Could you review this patch?

Martin,

Can we move forward with this one?

Thanks,
Daejun

> Changelog:
> 
> v10 -> v11
> Add a newline at end the last line on Kconfig file.
> 
> v9 -> v10
> 1. Fix 64-bit division error
> 2. Fix problems commentted in Bart's review.
> 
> v8 -> v9
> 1. Change sysfs initialization.
> 2. Change reading descriptor during HPB initialization
> 3. Fix problems commentted in Bart's review.
> 4. Change base commit from 5.9/scsi-queue to 5.10/scsi-queue.
> 
> v7 -> v8
> Remove wrongly added tags.
> 
> 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 HPB feature related parameters
>  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  |   10 +
>  drivers/scsi/ufs/Makefile |    1 +
>  drivers/scsi/ufs/ufs.h    |   47 +
>  drivers/scsi/ufs/ufshcd.c |   60 ++
>  drivers/scsi/ufs/ufshcd.h |   23 +-
>  drivers/scsi/ufs/ufshpb.c | 1845 ++++++++++++++++++++++++++++++++++++++++
>  drivers/scsi/ufs/ufshpb.h |  229 +++++
>  7 files changed, 2214 insertions(+), 1 deletion(-)
>  created mode 100644 drivers/scsi/ufs/ufshpb.c
>  created mode 100644 drivers/scsi/ufs/ufshpb.h