[PATCH v9 00/17] Improve performance for zoned UFS devices

Bart Van Assche
2023-08-16T19:55:53Z

Hi Jens,

This patch series improves small write IOPS by a factor of four (+300%) for
zoned UFS devices on my test setup with an UFSHCI 3.0 controller. Please
consider this patch series for the next merge window.

Thank you,

Bart.

Changes compared to v8:
- Fixed handling of 'driver_preserves_write_order' and 'use_zone_write_lock'
in blk_stack_limits().
- Added a comment in disk_set_zoned().
- Modified blk_req_needs_zone_write_lock() such that it returns false if
q->limits.use_zone_write_lock is false.
- Modified disk_clear_zone_settings() such that it clears
q->limits.use_zone_write_lock.
- Left out one change from the mq-deadline patch that became superfluous due to
the blk_req_needs_zone_write_lock() change.
- Modified scsi_call_prepare_resubmit() such that it only calls list_sort() if
zoned writes have to be resubmitted for which zone write locking is disabled.
- Added an additional unit test for scsi_call_prepare_resubmit().
- Modified the sorting code in the sd driver such that only those SCSI commands
are sorted for which write locking is disabled.
- Modified sd_zbc.c such that ELEVATOR_F_ZBD_SEQ_WRITE is only set if the
write order is not preserved.
- Included three patches for UFS host drivers that rework code that wrote
directly to the auto-hibernation controller register.
- Modified the UFS driver such that enabling auto-hibernation is not allowed
if a zoned logical unit is present and if the controller operates in legacy
mode.
- Also in the UFS driver, simplified ufshcd_auto_hibern8_update().

Changes compared to v7:
- Split the queue_limits member variable `use_zone_write_lock' into two member
variables: `use_zone_write_lock' (set by disk_set_zoned()) and
`driver_preserves_write_order' (set by the block driver or SCSI LLD). This
should clear up the confusion about the purpose of this variable.
- Moved the code for sorting SCSI commands by LBA from the SCSI error handler
into the SCSI disk (sd) driver as requested by Christoph.

Changes compared to v6:
- Removed QUEUE_FLAG_NO_ZONE_WRITE_LOCK and instead introduced a flag in
the request queue limits data structure.

Changes compared to v5:
- Renamed scsi_cmp_lba() into scsi_cmp_sector().
- Improved several source code comments.

Changes compared to v4:
- Dropped the patch that introduces the REQ_NO_ZONE_WRITE_LOCK flag.
- Dropped the null_blk patch and added two scsi_debug patches instead.
- Dropped the f2fs patch.
- Split the patch for the UFS driver into two patches.
- Modified several patch descriptions and source code comments.
- Renamed dd_use_write_locking() into dd_use_zone_write_locking().
- Moved the list_sort() call from scsi_unjam_host() into scsi_eh_flush_done_q()
such that sorting happens just before reinserting.
- Removed the scsi_cmd_retry_allowed() call from scsi_check_sense() to make
sure that the retry counter is adjusted once per retry instead of twice.

Changes compared to v3:
- Restored the patch that introduces QUEUE_FLAG_NO_ZONE_WRITE_LOCK. That patch
had accidentally been left out from v2.
- In patch "block: Introduce the flag REQ_NO_ZONE_WRITE_LOCK", improved the
patch description and added the function blk_no_zone_write_lock().
- In patch "block/mq-deadline: Only use zone locking if necessary", moved the
blk_queue_is_zoned() call into dd_use_write_locking().
- In patch "fs/f2fs: Disable zone write locking", set REQ_NO_ZONE_WRITE_LOCK
from inside __bio_alloc() instead of in f2fs_submit_write_bio().

Changes compared to v2:
- Renamed the request queue flag for disabling zone write locking.
- Introduced a new request flag for disabling zone write locking.
- Modified the mq-deadline scheduler such that zone write locking is only
disabled if both flags are set.
- Added an F2FS patch that sets the request flag for disabling zone write
locking.
- Only disable zone write locking in the UFS driver if auto-hibernation is
disabled.

Changes compared to v1:
- Left out the patches that are already upstream.
- Switched the approach in patch "scsi: Retry unaligned zoned writes" from
retrying immediately to sending unaligned write commands to the SCSI error
handler.

Bart Van Assche (17):
block: Introduce more member variables related to zone write locking
block: Only use write locking if necessary
block/mq-deadline: Only use zone locking if necessary
scsi: core: Call .eh_prepare_resubmit() before resubmitting
scsi: core: Add unit tests for scsi_call_prepare_resubmit()
scsi: sd: Sort commands by LBA before resubmitting
scsi: core: Retry unaligned zoned writes
scsi: sd_zbc: Only require an I/O scheduler if needed
scsi: scsi_debug: Support disabling zone write locking
scsi: scsi_debug: Support injecting unaligned write errors
scsi: ufs: hisi: Rework the code that disables auto-hibernation
scsi: ufs: mediatek: Rework the code for disabling auto-hibernation
scsi: ufs: sprd: Rework the code for disabling auto-hibernation
scsi: ufs: Rename ufshcd_auto_hibern8_enable() and make it static
scsi: ufs: Simplify ufshcd_auto_hibern8_update()
scsi: ufs: Forbid auto-hibernation without I/O scheduler
scsi: ufs: Inform the block layer about write ordering

block/blk-settings.c | 15 +++
block/blk-zoned.c | 10 +-
block/mq-deadline.c | 11 +-
drivers/scsi/Kconfig | 2 +
drivers/scsi/Kconfig.kunit | 4 +
drivers/scsi/Makefile | 2 +
drivers/scsi/Makefile.kunit | 1 +
drivers/scsi/scsi_debug.c | 20 +++-
drivers/scsi/scsi_error.c | 81 +++++++++++++
drivers/scsi/scsi_error_test.c | 196 ++++++++++++++++++++++++++++++++
drivers/scsi/scsi_lib.c | 1 +
drivers/scsi/scsi_priv.h | 1 +
drivers/scsi/sd.c | 41 +++++++
drivers/scsi/sd_zbc.c | 4 +-
drivers/ufs/core/ufs-sysfs.c | 2 +-
drivers/ufs/core/ufshcd-priv.h | 1 -
drivers/ufs/core/ufshcd.c | 110 ++++++++++++++----
drivers/ufs/host/ufs-hisi.c | 5 +-
drivers/ufs/host/ufs-mediatek.c | 2 +-
drivers/ufs/host/ufs-sprd.c | 11 +-
include/linux/blkdev.h | 10 ++
include/scsi/scsi.h | 1 +
include/scsi/scsi_driver.h | 1 +
include/ufs/ufshcd.h | 3 +-
24 files changed, 485 insertions(+), 50 deletions(-)
create mode 100644 drivers/scsi/Kconfig.kunit
create mode 100644 drivers/scsi/Makefile.kunit
create mode 100644 drivers/scsi/scsi_error_test.c