Hello Jens, 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 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 (6): 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 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 | 271 +++++----------------------------------- block/blk-mq-debugfs.c | 10 +- block/blk-mq.c | 2 + block/blk-pm.c | 244 ++++++++++++++++++++++++++++++++++++ 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 ++---- 14 files changed, 402 insertions(+), 295 deletions(-) create mode 100644 block/blk-pm.c create mode 100644 block/blk-pm.h create mode 100644 include/linux/blk-pm.h -- 2.18.0