| Message ID | 20221102053058.21021-1-lijiaming3@xiaomi.corp-partner.google.com |
|---|---|
| Headers | show |
| Series | Implement File-Based optimization functionality | expand |
On Thu, Nov 03, 2022 at 03:11:16PM +0900, Juhyung Park wrote: > Is the idea really an utter madness? Yes. > Majority of regular files that may be > of interest from the perspective of UFS aren't reflinked or snapshotted (let > alone the lack of support from ext4 or f2fs). Linux does not require you in any way to use obsolete file systems desings only on any given block device. > Device-side fragmentation is a real issue [1] and it makes more than enough > sense to defrag LBAs of interests to improve performance. This was long > overdue, unless the block interface itself changes somehow. Or maybe random writes to flash aren't a good idea if you FTL sucks? Full blown FTLs tend to not do any extent based mappings, so fragmentation does not matter. The price paid for that is much larger FTL tables. If you stop pretending flash is random writable through saner interfaces like ZNS you automatically solve this fragmentation problem as well. > The question is how to implement it correctly without creating a mess with > mismatched/outdated LBAs as you've mentioned, preferably through > file-system's integration: If the LBAs in questions are indeed reflinked, > how do we handle it?, If the LBAs are moved/invalidated from defrag or GC, > how do we make sure that UFS is up-to-date?, etc. The fix is to plug the leaking abtractions in UFS. If it wants to look like a random writable block device it better perform when doing that. And if it doesn't want to pay the prize for that it'd better expose an abstraction that actually fits the underlying media. It's not like some of us haven't worked on that for the last decade.
From: lijiaming3 <lijiaming3@xiaomi.com> Stoage devices have a long lifespan. Device performance over its lifespan is not constant and may deteriorate over time. To remedy this, JEDEC came up with the UFS File-Based-Optimization (FBO) extension (JC-64.1-22-67). The FBO feature improves this performance regression via physical defragmentation of the LBA ranges that are associated with specific files. This feature expects the following host-device dialog: 1) The host let the device know of lba range(s) of interest. Those ranges are typically associated with a specific file. One can obtain it from the iNode of the file and some offset calculations. 2) The host ask the device for the current physical fragmentation level of this file. 3) Should it requires, the host instruct the device to perform defragmentation. 4) Upon successful termination of the defragmentation phase, the host may ask for the new fragmentation level of the file. lijiaming3 (4): scsi:ufs:remove sanity check scsi:ufs:add File-Based Optimization descriptor scsi:ufs:add FBO module scsi:ufs:add fbo functionality Documentation/ABI/testing/sysfs-driver-ufs | 129 +++++ drivers/ufs/core/Kconfig | 12 + drivers/ufs/core/Makefile | 1 + drivers/ufs/core/ufs-sysfs.c | 26 ++ drivers/ufs/core/ufsfbo.c | 519 +++++++++++++++++++++ drivers/ufs/core/ufsfbo.h | 23 + drivers/ufs/core/ufshcd.c | 15 +- include/ufs/ufs.h | 16 + include/ufs/ufshcd.h | 1 + 9 files changed, 734 insertions(+), 8 deletions(-) create mode 100644 drivers/ufs/core/ufsfbo.c create mode 100644 drivers/ufs/core/ufsfbo.h