Re: [PATCH V9 00/15] mmc: Add Command Queue support

[Ulf Hansson]

On 22 September 2017 at 14:36, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
> Hi
>
> Here is V9 of the hardware command queue patches without the software
> command queue patches, now using blk-mq and now with blk-mq support for
> non-CQE I/O.
>
> HW CMDQ offers 25% - 50% better random multi-threaded I/O.  I see a slight
> 2% drop in sequential read speed but no change to sequential write.
>
> Non-CQE blk-mq showed a 3% decrease in sequential read performance.  This
> seemed to be coming from the inferior latency of running work items compared
> with a dedicated thread.  Hacking blk-mq workqueue to be unbound reduced the
> performance degradation from 3% to 1%.
>
> While we should look at changing blk-mq to give better workqueue performance,
> a bigger gain is likely to be made by adding a new host API to enable the
> next already-prepared request to be issued directly from within ->done()
> callback of the current request.

I have looked at patch 1->8, and those looks nice to me so I have
applied those for next. I will do my best to review the rest asap,
however I am currently traveling so in worst case it will have wait
until next week.

Thanks and kind regards!
Uffe

>
>
> Changes since V8:
>         Re-based
>       mmc: core: Introduce host claiming by context
>         Slightly simplified as per Ulf
>       mmc: core: Export mmc_retune_hold_now() and mmc_retune_release()
>         New patch.
>       mmc: block: Add CQE and blk-mq support
>         Fix missing ->post_req() on the error path
>
> Changes since V7:
>         Re-based
>       mmc: core: Introduce host claiming by context
>         Slightly simplified
>       mmc: core: Add parameter use_blk_mq
>         New patch.
>       mmc: core: Remove unnecessary host claim
>         New patch.
>       mmc: core: Export mmc_start_bkops()
>         New patch.
>       mmc: core: Export mmc_start_request()
>         New patch.
>       mmc: block: Add CQE and blk-mq support
>         Add blk-mq support for non_CQE requests
>
> Changes since V6:
>       mmc: core: Introduce host claiming by context
>         New patch.
>       mmc: core: Move mmc_start_areq() declaration
>         Dropped because it has been applied
>       mmc: block: Fix block status codes
>         Dropped because it has been applied
>       mmc: host: Add CQE interface
>         Dropped because it has been applied
>       mmc: core: Turn off CQE before sending commands
>         Dropped because it has been applied
>       mmc: block: Factor out mmc_setup_queue()
>         New patch.
>       mmc: block: Add CQE support
>         Drop legacy support and add blk-mq support
>
> Changes since V5:
>         Re-based
>       mmc: core: Add mmc_retune_hold_now()
>         Dropped because it has been applied
>       mmc: core: Add members to mmc_request and mmc_data for CQE's
>         Dropped because it has been applied
>       mmc: core: Move mmc_start_areq() declaration
>         New patch at Ulf's request
>       mmc: block: Fix block status codes
>         Another un-related patch
>       mmc: host: Add CQE interface
>         Move recovery_notifier() callback to struct mmc_request
>       mmc: core: Add support for handling CQE requests
>         Roll __mmc_cqe_request_done() into mmc_cqe_request_done()
>         Move function declarations requested by Ulf
>       mmc: core: Remove unused MMC_CAP2_PACKED_CMD
>         Dropped because it has been applied
>       mmc: block: Add CQE support
>         Add explanation to commit message
>         Adjustment for changed recovery_notifier() callback
>       mmc: cqhci: support for command queue enabled host
>         Adjustment for changed recovery_notifier() callback
>       mmc: sdhci-pci: Add CQHCI support for Intel GLK
>         Add DCMD capability for Intel controllers except GLK
>
> Changes since V4:
>       mmc: core: Add mmc_retune_hold_now()
>         Add explanation to commit message.
>       mmc: host: Add CQE interface
>         Add comments to callback declarations.
>       mmc: core: Turn off CQE before sending commands
>         Add explanation to commit message.
>       mmc: core: Add support for handling CQE requests
>         Add comments as requested by Ulf.
>       mmc: core: Remove unused MMC_CAP2_PACKED_CMD
>         New patch.
>       mmc: mmc: Enable Command Queuing
>         Adjust for removal of MMC_CAP2_PACKED_CMD.
>         Add a comment about Packed Commands.
>       mmc: mmc: Enable CQE's
>         Remove un-necessary check for MMC_CAP2_CQE
>       mmc: block: Use local variables in mmc_blk_data_prep()
>         New patch.
>       mmc: block: Prepare CQE data
>         Adjust due to "mmc: block: Use local variables in mmc_blk_data_prep()"
>         Remove priority setting.
>         Add explanation to commit message.
>       mmc: cqhci: support for command queue enabled host
>         Fix transfer descriptor setting in cqhci_set_tran_desc() for 32-bit DMA
>
> Changes since V3:
>         Adjusted ...blk_end_request...() for new block status codes
>         Fixed CQHCI transaction descriptor for "no DCMD" case
>
> Changes since V2:
>         Dropped patches that have been applied.
>         Re-based
>         Added "mmc: sdhci-pci: Add CQHCI support for Intel GLK"
>
> Changes since V1:
>
>         "Share mmc request array between partitions" is dependent
>         on changes in "Introduce queue semantics", so added that
>         and block fixes:
>
>         Added "Fix is_waiting_last_req set incorrectly"
>         Added "Fix cmd error reset failure path"
>         Added "Use local var for mqrq_cur"
>         Added "Introduce queue semantics"
>
> Changes since RFC:
>
>         Re-based on next.
>         Added comment about command queue priority.
>         Added some acks and reviews.
>
>
> Adrian Hunter (14):
>       mmc: core: Remove unnecessary host claim
>       mmc: core: Introduce host claiming by context
>       mmc: core: Add support for handling CQE requests
>       mmc: mmc: Enable Command Queuing
>       mmc: mmc: Enable CQE's
>       mmc: block: Use local variables in mmc_blk_data_prep()
>       mmc: block: Prepare CQE data
>       mmc: block: Factor out mmc_setup_queue()
>       mmc: core: Add parameter use_blk_mq
>       mmc: core: Export mmc_start_bkops()
>       mmc: core: Export mmc_start_request()
>       mmc: core: Export mmc_retune_hold_now() and mmc_retune_release()
>       mmc: block: Add CQE and blk-mq support
>       mmc: sdhci-pci: Add CQHCI support for Intel GLK
>
> Venkat Gopalakrishnan (1):
>       mmc: cqhci: support for command queue enabled host
>
>  drivers/mmc/Kconfig               |   11 +
>  drivers/mmc/core/block.c          |  779 ++++++++++++++++++++++++-
>  drivers/mmc/core/block.h          |    8 +
>  drivers/mmc/core/bus.c            |    7 +
>  drivers/mmc/core/core.c           |  221 ++++++-
>  drivers/mmc/core/core.h           |   17 +-
>  drivers/mmc/core/host.c           |    9 +-
>  drivers/mmc/core/host.h           |   11 +-
>  drivers/mmc/core/mmc.c            |   33 +-
>  drivers/mmc/core/mmc_ops.c        |    6 +-
>  drivers/mmc/core/queue.c          |  466 +++++++++++++--
>  drivers/mmc/core/queue.h          |   54 +-
>  drivers/mmc/core/sd.c             |    4 +-
>  drivers/mmc/core/sdio_irq.c       |    3 +-
>  drivers/mmc/host/Kconfig          |   14 +
>  drivers/mmc/host/Makefile         |    1 +
>  drivers/mmc/host/cqhci.c          | 1154 +++++++++++++++++++++++++++++++++++++
>  drivers/mmc/host/cqhci.h          |  240 ++++++++
>  drivers/mmc/host/sdhci-pci-core.c |  155 ++++-
>  include/linux/mmc/host.h          |   10 +-
>  20 files changed, 3108 insertions(+), 95 deletions(-)
>  create mode 100644 drivers/mmc/host/cqhci.c
>  create mode 100644 drivers/mmc/host/cqhci.h
>
>
> Regards
> Adrian