Hello Jens,
One of the pieces that is missing before blk-mq can be made the default is
implementing runtime power management support for blk-mq. This patch series
not only implements runtime power management for blk-mq but also fixes a
starvation issue in the power management code for the legacy block
layer. Please consider this patch series for the upstream kernel.
Thanks,
Bart.
Changes compared to v9:
- Left out the patches that document the functions that iterate over requests
and also the patch that introduces blk_mq_queue_rq_iter().
- Simplified blk_pre_runtime_suspend(): left out the check whether no requests
are in progress.
- Fixed the race between blk_queue_enter(), queue freezing and runtime power
management that Ming had identified.
- Added a new patch that introduces percpu_ref_resurrect().
Changes compared to v8:
- Fixed the race that was reported by Jianchao.
- Fixed another spelling issue in a source code comment.
Changes compared to v7:
- Addressed Jianchao's feedback about patch "Make blk_get_request() block for
non-PM requests while suspended".
- Added two new patches - one that documents the functions that iterate over
requests and one that introduces a new function that iterates over all
requests associated with a queue.
Changes compared to v6:
- Left out the patches that split RQF_PREEMPT in three flags.
- Left out the patch that introduces the SCSI device state SDEV_SUSPENDED.
- Left out the patch that introduces blk_pm_runtime_exit().
- Restored the patch that changes the PREEMPT_ONLY flag into a counter.
Changes compared to v5:
- Introduced a new flag RQF_DV that replaces RQF_PREEMPT for SCSI domain
validation.
- Introduced a new request queue state QUEUE_FLAG_DV_ONLY for SCSI domain
validation.
- Instead of using SDEV_QUIESCE for both runtime suspend and SCSI domain
validation, use that state for domain validation only and introduce a new
state for runtime suspend, namely SDEV_QUIESCE.
- Reallow system suspend during SCSI domain validation.
- Moved the runtime resume call from the request allocation code into
blk_queue_enter().
- Instead of relying on q_usage_counter, iterate over the tag set to determine
whether or not any requests are in flight.
Changes compared to v4:
- Dropped the patches "Give RQF_PREEMPT back its original meaning" and
"Serialize queue freezing and blk_pre_runtime_suspend()".
- Replaced "percpu_ref_read()" with "percpu_is_in_use()".
- Inserted pm_request_resume() calls in the block layer request allocation
code such that the context that submits a request no longer has to call
pm_runtime_get().
Changes compared to v3:
- Avoid adverse interactions between system-wide suspend/resume and runtime
power management by changing the PREEMPT_ONLY flag into a counter.
- Give RQF_PREEMPT back its original meaning, namely that it is only set for
ide_preempt requests.
- Remove the flag BLK_MQ_REQ_PREEMPT.
- Removed the pm_request_resume() call.
Changes compared to v2:
- Fixed the build for CONFIG_BLOCK=n.
- Added a patch that introduces percpu_ref_read() in the percpu-counter code.
- Added a patch that makes it easier to detect missing pm_runtime_get*() calls.
- Addressed Jianchao's feedback including the comment about runtime overhead
of switching a per-cpu counter to atomic mode.
Changes compared to v1:
- Moved the runtime power management code into a separate file.
- Addressed Ming's feedback.
Bart Van Assche (8):
block: Move power management code into a new source file
block, scsi: Change the preempt-only flag into a counter
block: Split blk_pm_add_request() and blk_pm_put_request()
block: Schedule runtime resume earlier
percpu-refcount: Introduce percpu_ref_resurrect()
block: Allow unfreezing of a queue while requests are in progress
block: Make blk_get_request() block for non-PM requests while
suspended
blk-mq: Enable support for runtime power management
block/Kconfig | 3 +
block/Makefile | 1 +
block/blk-core.c | 270 ++++----------------------------
block/blk-mq-debugfs.c | 10 +-
block/blk-mq.c | 4 +-
block/blk-pm.c | 216 +++++++++++++++++++++++++
block/blk-pm.h | 69 ++++++++
block/elevator.c | 22 +--
drivers/scsi/scsi_lib.c | 11 +-
drivers/scsi/scsi_pm.c | 1 +
drivers/scsi/sd.c | 1 +
drivers/scsi/sr.c | 1 +
include/linux/blk-pm.h | 24 +++
include/linux/blkdev.h | 37 ++---
include/linux/percpu-refcount.h | 1 +
lib/percpu-refcount.c | 28 +++-
16 files changed, 401 insertions(+), 298 deletions(-)
create mode 100644 block/blk-pm.c
create mode 100644 block/blk-pm.h
create mode 100644 include/linux/blk-pm.h
--
2.19.0.444.g18242da7ef-goog
