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 kernel v4.19. Thanks, Bart. 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 (9): block: Change the preempt-only flag into a counter block: Move power management code into a new source file block, scsi: Introduce blk_pm_runtime_exit() percpu-refcount: Introduce percpu_ref_is_in_use() block: Change the runtime power management approach (1/2) block: Change the runtime power management approach (2/2) block: Remove blk_pm_requeue_request() blk-mq: Insert a blk_pm_put_request() call blk-mq: Enable support for runtime power management block/Kconfig | 5 + block/Makefile | 1 + block/blk-core.c | 277 ++++---------------------------- block/blk-mq-debugfs.c | 11 +- block/blk-mq.c | 8 + block/blk-pm.c | 230 ++++++++++++++++++++++++++ block/blk-pm.h | 33 ++++ block/elevator.c | 26 +-- drivers/scsi/scsi_lib.c | 17 +- drivers/scsi/scsi_pm.c | 1 + drivers/scsi/sd.c | 10 +- drivers/scsi/sr.c | 4 +- include/linux/blk-mq.h | 2 + include/linux/blk-pm.h | 26 +++ include/linux/blkdev.h | 38 ++--- include/linux/percpu-refcount.h | 2 + lib/percpu-refcount.c | 40 +++++ 17 files changed, 420 insertions(+), 311 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
