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Date:   Wed, 9 Jun 2021 11:53:48 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Daejun Park <daejun7.park@samsung.com>
Cc:     "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>,
        "stanley.chu@mediatek.com" <stanley.chu@mediatek.com>,
        "cang@codeaurora.org" <cang@codeaurora.org>,
        "bvanassche@acm.org" <bvanassche@acm.org>,
        "huobean@gmail.com" <huobean@gmail.com>,
        ALIM AKHTAR <alim.akhtar@samsung.com>,
        "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        JinHwan Park <jh.i.park@samsung.com>,
        Javier Gonzalez <javier.gonz@samsung.com>,
        Sung-Jun Park <sungjun07.park@samsung.com>,
        Jinyoung CHOI <j-young.choi@samsung.com>,
        Dukhyun Kwon <d_hyun.kwon@samsung.com>,
        Keoseong Park <keosung.park@samsung.com>,
        Jaemyung Lee <jaemyung.lee@samsung.com>,
        Jieon Seol <jieon.seol@samsung.com>
Subject: Re: [PATCH v36 0/4] scsi: ufs: Add Host Performance Booster Support
Message-ID: <YMCPrE+Fq+ee+vBS@kroah.com>
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On Mon, Jun 07, 2021 at 01:16:50PM +0900, Daejun Park wrote:
> Changelog:
> 
> v35 -> v36
> 1. Changed ppn variable type from u64 to __be64.
> 2. Added WARN_ON_ONCE() to check for HPB read IO size exceeded.
> 
> v34 -> v35
> 1. Addressed Bart's comments (type casting)
> 2. Rebase 5.14 scsi-queue
> 
> v33 -> v34
> Fix warning about NULL check before some freeing functions is not needed.
> 
> v32 -> v33
> 1. Fix wrong usage of scsi_command_normalize_sense.
> 2. Addressed Bart's comments (func. name, type casting, parentheses)
> 
> v31 -> v32
> Delete unused parameter of unmap API.
> 
> v30 -> v31
> Delete unnecessary debug message.
> 
> v29 -> v30
> 1. Add support to reuse bio of pre-request.
> 2. Delete unreached code in the ufshpb_issue_map_req.
> 
> v28 -> v29
> 1. Remove unused variable that reported by kernel test robot.
> 
> v27 -> v28
> 1. Fix wrong return value of ufshpb_prep.
> 
> v26 -> v27
> 1. Fix wrong refernce of sense buffer in pre_req complete function.
> 2. Fix read_id error.
> 3. Fix chunk size checking for HPB 1.0.
> 4. Mute unnecessary messages before HPB initialization.
> 
> v25 -> v26
> 1. Fix wrong chunk size checking for HPB 1.0.
> 2. Fix wrong max data size for HPB single command.
> 3. Fix typo error.
> 
> v24 -> v25
> 1. Change write buffer API for unmap region.
> 2. Add checking hpb_enable for avoiding unnecessary memory allocation.
> 3. Change pr_info to dev_info.
> 4. Change default requeue timeout value for HPB read.
> 5. Fix wrong offset manipulation on ufshpb_prep_entry.
> 
> v23 -> v24
> 1. Fix build error reported by kernel test robot.
> 
> v22 -> v23
> 1. Add support compatibility of HPB 1.0.
> 2. Fix read id for single HPB read command.
> 3. Fix number of pre-allocated requests for write buffer.
> 4. Add fast path for response UPIU that has same LUN in sense data.
> 5. Remove WARN_ON for preventing kernel crash.
> 7. Fix wrong argument for read buffer command.
> 
> v21 -> v22
> 1. Add support processing response UPIU in suspend state.
> 2. Add support HPB hint from other LU.
> 3. Add sending write buffer with 0x03 after HPB init.
> 
> v20 -> v21
> 1. Add bMAX_DATA_SIZE_FOR_HPB_SINGLE_CMD attr. and fHPBen flag support.
> 
> v19 -> v20
> 1. Add documentation for sysfs entries of hpb->stat.
> 2. Fix read buffer command for under-sized sub-region.
> 3. Fix wrong condition checking for kick map work.
> 4. Delete redundant response UPIU checking.
> 5. Add LUN checking in response UPIU.
> 6. Fix possible deadlock problem due to runtime PM.
> 7. Add instant changing of sub-region state from response UPIU.
> 8. Fix endian problem in prefetched PPN.
> 9. Add JESD220-3A (HPB v2.0) support.
> 
> v18 -> 19
> 1. Fix null pointer error when printing sysfs from non-HPB LU.
> 2. Apply HPB read opcode in lrbp->cmd->cmnd (from Can Guo's review).
> 3. Rebase the patch on 5.12/scsi-queue.
> 
> v17 -> v18
> Fix build error which reported by kernel test robot.
> 
> v16 -> v17
> 1. Rename hpb_state_lock to rgn_state_lock and move it to corresponding
> patch.
> 2. Remove redundant information messages.
> 
> v15 -> v16
> 1. Add missed sysfs ABI documentation.
> 
> v14 -> v15
> 1. Remove duplicated sysfs ABI entries in documentation.
> 2. Add experiment result of HPB performance testing with iozone.
> 
> v13 -> v14
> 1. Cleanup codes by commentted in Greg's review.
> 2. Add documentation for sysfs entries (from Greg's review).
> 3. Add experiment result of HPB performance testing.
> 
> v12 -> v13
> 1. Cleanup codes by comments from Can Guo.
> 2. Add HPB related descriptor/flag/attributes in sysfs.
> 3. Change base commit from 5.10/scsi-queue to 5.11/scsi-queue.
> 
> v11 -> v12
> 1. Fixed to return error value when HPB fails to initialize pinned active 
> region.
> 2. Fixed to disable HPB feature if HPB fails to allocate essential memory
> and workqueue.
> 3. Fixed to change proper sub-region state when region is already evicted.
> 
> v10 -> v11
> Add a newline at end the last line on Kconfig file.
> 
> v9 -> v10
> 1. Fixed 64-bit division error
> 2. Fixed problems commentted in Bart's review.
> 
> v8 -> v9
> 1. Change sysfs initialization.
> 2. Change reading descriptor during HPB initialization
> 3. Fixed 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]
> 
> [1]:
> https://www.usenix.org/conference/hotstorage17/program/presentation/jeong
> 
> Daejun Park (4):
>   scsi: ufs: Introduce HPB feature
>   scsi: ufs: L2P map management for HPB read
>   scsi: ufs: Prepare HPB read for cached sub-region
>   scsi: ufs: Add HPB 2.0 support

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>