[PATCH V5 00/25] mmc: mmc: Add Software Command Queuing

[Adrian Hunter <adrian.hunter@intel.com>]

Hi

Here is an updated version of the Software Command Queuing patches,
re-based on next, with patches 1-5 dropped because they have been applied,
and 2 fixes that have been rolled in (refer Changes in V5 below).

Performance results:

Results can vary from run to run, but here are some results showing 1, 2 or 4
processes with 4k and 32k record sizes.  They show up to 40% improvement in
read performance when there are multiple processes.

iozone -s 8192k -r 4k -i 0 -i 1 -i 2 -i 8 -I -t 1 -F /mnt/mmc/iozone1.tmp

	Children see throughput for  1 initial writers 	=     27909.87 kB/sec     24204.14 kB/sec      -13.28 %
	Children see throughput for  1 rewriters 	=     28839.28 kB/sec     25531.92 kB/sec      -11.47 %
	Children see throughput for  1 readers 		=     25889.65 kB/sec     24883.23 kB/sec       -3.89 %
	Children see throughput for 1 re-readers 	=     25558.23 kB/sec     24679.89 kB/sec       -3.44 %
	Children see throughput for 1 random readers 	=     25571.48 kB/sec     24689.52 kB/sec       -3.45 %
	Children see throughput for 1 mixed workload 	=     25758.59 kB/sec     24487.52 kB/sec       -4.93 %
	Children see throughput for 1 random writers 	=     24787.51 kB/sec     19368.99 kB/sec      -21.86 %

iozone -s 8192k -r 32k -i 0 -i 1 -i 2 -i 8 -I -t 1 -F /mnt/mmc/iozone1.tmp

	Children see throughput for  1 initial writers 	=     91344.61 kB/sec    102008.56 kB/sec       11.67 %
	Children see throughput for  1 rewriters 	=     87932.36 kB/sec     96630.44 kB/sec        9.89 %
	Children see throughput for  1 readers 		=    134879.82 kB/sec    110292.79 kB/sec      -18.23 %
	Children see throughput for 1 re-readers 	=    147632.13 kB/sec    109053.33 kB/sec      -26.13 %
	Children see throughput for 1 random readers 	=     93547.37 kB/sec    112225.50 kB/sec       19.97 %
	Children see throughput for 1 mixed workload 	=     93560.04 kB/sec    110515.21 kB/sec       18.12 %
	Children see throughput for 1 random writers 	=     92841.84 kB/sec     81153.81 kB/sec      -12.59 %

iozone -s 8192k -r 4k -i 0 -i 1 -i 2 -i 8 -I -t 2 -F /mnt/mmc/iozone1.tmp /mnt/mmc/iozone2.tmp

	Children see throughput for  2 initial writers 	=     31145.43 kB/sec     33771.25 kB/sec        8.43 %
	Children see throughput for  2 rewriters 	=     30592.57 kB/sec     35916.46 kB/sec       17.40 %
	Children see throughput for  2 readers 		=     31669.83 kB/sec     37460.13 kB/sec       18.28 %
	Children see throughput for 2 re-readers 	=     32079.94 kB/sec     37373.33 kB/sec       16.50 %
	Children see throughput for 2 random readers 	=     27731.19 kB/sec     37601.65 kB/sec       35.59 %
	Children see throughput for 2 mixed workload 	=     13927.50 kB/sec     14617.06 kB/sec        4.95 %
	Children see throughput for 2 random writers 	=     31250.00 kB/sec     33106.72 kB/sec        5.94 %

iozone -s 8192k -r 32k -i 0 -i 1 -i 2 -i 8 -I -t 2 -F /mnt/mmc/iozone1.tmp /mnt/mmc/iozone2.tmp

	Children see throughput for  2 initial writers 	=    123255.84 kB/sec    131252.22 kB/sec        6.49 %
	Children see throughput for  2 rewriters 	=    115234.91 kB/sec    107225.74 kB/sec       -6.95 %
	Children see throughput for  2 readers 		=    128921.86 kB/sec    148562.71 kB/sec       15.23 %
	Children see throughput for 2 re-readers 	=    127815.24 kB/sec    149304.32 kB/sec       16.81 %
	Children see throughput for 2 random readers 	=    125600.46 kB/sec    148406.56 kB/sec       18.16 %
	Children see throughput for 2 mixed workload 	=     44006.94 kB/sec     50937.36 kB/sec       15.75 %
	Children see throughput for 2 random writers 	=    120623.95 kB/sec    103969.05 kB/sec      -13.81 %

iozone -s 8192k -r 4k -i 0 -i 1 -i 2 -i 8 -I -t 4 -F /mnt/mmc/iozone1.tmp /mnt/mmc/iozone2.tmp /mnt/mmc/iozone3.tmp /mnt/mmc/iozone4.tmp

	Children see throughput for  4 initial writers 	=     24100.96 kB/sec     33336.58 kB/sec       38.32 %
	Children see throughput for  4 rewriters 	=     31650.20 kB/sec     33091.53 kB/sec        4.55 %
	Children see throughput for  4 readers 		=     33276.92 kB/sec     41799.89 kB/sec       25.61 %
	Children see throughput for 4 re-readers 	=     31786.96 kB/sec     41501.74 kB/sec       30.56 %
	Children see throughput for 4 random readers 	=     31991.65 kB/sec     40973.93 kB/sec       28.08 %
	Children see throughput for 4 mixed workload 	=     15804.80 kB/sec     13581.32 kB/sec      -14.07 %
	Children see throughput for 4 random writers 	=     31231.42 kB/sec     34537.03 kB/sec       10.58 %

iozone -s 8192k -r 32k -i 0 -i 1 -i 2 -i 8 -I -t 4 -F /mnt/mmc/iozone1.tmp /mnt/mmc/iozone2.tmp /mnt/mmc/iozone3.tmp /mnt/mmc/iozone4.tmp

	Children see throughput for  4 initial writers 	=    116567.42 kB/sec    119280.35 kB/sec        2.33 %
	Children see throughput for  4 rewriters 	=    115010.96 kB/sec    120864.34 kB/sec        5.09 %
	Children see throughput for  4 readers 		=    130700.29 kB/sec    177834.21 kB/sec       36.06 %
	Children see throughput for 4 re-readers 	=    125392.58 kB/sec    175975.28 kB/sec       40.34 %
	Children see throughput for 4 random readers 	=    132194.57 kB/sec    176630.46 kB/sec       33.61 %
	Children see throughput for 4 mixed workload 	=     56464.98 kB/sec     54140.61 kB/sec       -4.12 %
	Children see throughput for 4 random writers 	=    109128.36 kB/sec     85359.80 kB/sec      -21.78 %


The current block driver supports 2 requests on the go at a time. Patches
1 - 8 make preparations for an arbitrary sized queue. Patches 9 - 12
introduce Command Queue definitions and helpers.  Patches 13 - 19
complete the job of making the block driver use a queue.  Patches 20 - 23
finally add Software Command Queuing, and 24 - 25 enable it for Intel eMMC
controllers. Most of the Software Command Queuing functionality is added
in patch 22.

As noted below, the patches can also be found here:

	http://git.infradead.org/users/ahunter/linux-sdhci.git/shortlog/refs/heads/swcmdq

Changes in V5:

  Patches 1-5 dropped because they have been applied.
 
  Re-based on next.
 
  Fixed use of blk_end_request_cur() when it should have been
  blk_end_request_all() to error out requests during error recovery.

  Fixed unpaired retune_hold / retune_release in the error recovery path.

Changes in V4:

  Re-based on next + v4.8-rc2 + "block: Fix secure erase" patch

Changes in V3:

  Patches 1-25 dropped because they have been applied.

  Re-based on next.

  mmc: queue: Allocate queue of size qdepth
    Free queue during cleanup

  mmc: mmc: Add Command Queue definitions
    Add cmdq_en to mmc-dev-attrs.txt documentation

  mmc: queue: Share mmc request array between partitions
    New patch

Changes in V2:

  Added 5 patches already sent here:

    http://marc.info/?l=linux-mmc&m=146712062816835

  Added 3 more new patches:

    mmc: sdhci-pci: Do not runtime suspend at the end of sdhci_pci_probe()
    mmc: sdhci: Avoid STOP cmd triggering warning in sdhci_send_command()
    mmc: sdhci: sdhci_execute_tuning() must delete timer

  Carried forward the V2 fix to:

    mmc: mmc_test: Disable Command Queue while mmc_test is used

  Also reset the cmd circuit for data timeout if it is processing the data
  cmd, in patch:

    mmc: sdhci: Do not reset cmd or data circuits that are in use

There wasn't much comment on the RFC so there have been few changes.
Venu Byravarasu commented that it may be more efficient to use Software
Command Queuing only when there is more than 1 request queued - it isn't
obvious how well that would work in practice, but it could be added later
if it could be shown to be beneficial.

Original Cover Letter:

Chuanxiao Dong sent some patches last year relating to eMMC 5.1 Software
Command Queuing.  He did not follow-up but I have contacted him and he says
it is OK if I take over upstreaming the patches.

eMMC Command Queuing is a feature added in version 5.1.  The card maintains
a queue of up to 32 data transfers.  Commands CMD45/CMD45 are sent to queue
up transfers in advance, and then one of the transfers is selected to
"execute" by CMD46/CMD47 at which point data transfer actually begins.

The advantage of command queuing is that the card can prepare for transfers
in advance.  That makes a big difference in the case of random reads because
the card can start reading into its cache in advance.

A v5.1 host controller can manage the command queue itself, but it is also
possible for software to manage the queue using an non-v5.1 host controller
- that is what Software Command Queuing is.

Refer to the JEDEC (http://www.jedec.org/) eMMC v5.1 Specification for more
information about Command Queuing.

While these patches are heavily based on Dong's patches, there are some
changes:

SDHCI has been amended to support commands during transfer. That is a
generic change added in patches 1 - 5. [Those patches have now been applied]
In principle, that would also support SDIO's CMD52 during data transfer.

The original approach added multiple commands into the same request for
sending CMD44, CMD45 and CMD13. That is not strictly necessary and has
been omitted for now.

The original approach also called blk_end_request() from the mrq->done()
function, which means the upper layers learnt of completed requests
slightly earlier. That is not strictly related to Software Command Queuing
and is something that could potentially be done for all data requests.
That has been omitted for now.

The current block driver supports 2 requests on the go at a time. Patches
1 - 8 make preparations for an arbitrary sized queue. Patches 9 - 12
introduce Command Queue definitions and helpers.  Patches 13 - 19
complete the job of making the block driver use a queue.  Patches 20 - 23
finally add Software Command Queuing, and 24 - 25 enable it for Intel eMMC
controllers. Most of the Software Command Queuing functionality is added
in patch 22.

The patches can also be found here:

	http://git.infradead.org/users/ahunter/linux-sdhci.git/shortlog/refs/heads/swcmdq

The patches have only had basic testing so far. Ad-hoc testing shows a
degradation in sequential read performance of about 10% but an increase in
throughput for mixed workload of multiple processes of about 90%. The
reduction in sequential performance is due to the need to read the Queue
Status register between each transfer.

These patches should not conflict with Hardware Command Queuing which
handles the queue in a completely different way and thus does not need
to share code with Software Command Queuing. The exceptions being the
Command Queue definitions and queue allocation which should be able to be
used.


Adrian Hunter (25):
      mmc: queue: Fix queue thread wake-up
      mmc: queue: Factor out mmc_queue_alloc_bounce_bufs()
      mmc: queue: Factor out mmc_queue_alloc_bounce_sgs()
      mmc: queue: Factor out mmc_queue_alloc_sgs()
      mmc: queue: Factor out mmc_queue_reqs_free_bufs()
      mmc: queue: Introduce queue depth
      mmc: queue: Use queue depth to allocate and free
      mmc: queue: Allocate queue of size qdepth
      mmc: mmc: Add Command Queue definitions
      mmc: mmc: Add functions to enable / disable the Command Queue
      mmc: mmc_test: Disable Command Queue while mmc_test is used
      mmc: block: Disable Command Queue while RPMB is used
      mmc: core: Do not prepare a new request twice
      mmc: core: Export mmc_retune_hold() and mmc_retune_release()
      mmc: block: Factor out mmc_blk_requeue()
      mmc: block: Fix 4K native sector check
      mmc: block: Use local var for mqrq_cur
      mmc: block: Pass mqrq to mmc_blk_prep_packed_list()
      mmc: block: Introduce queue semantics
      mmc: queue: Share mmc request array between partitions
      mmc: queue: Add a function to control wake-up on new requests
      mmc: block: Add Software Command Queuing
      mmc: mmc: Enable Software Command Queuing
      mmc: sdhci-pci: Enable Software Command Queuing for some Intel controllers
      mmc: sdhci-acpi: Enable Software Command Queuing for some Intel controllers

 Documentation/mmc/mmc-dev-attrs.txt |   1 +
 drivers/mmc/card/block.c            | 738 +++++++++++++++++++++++++++++++++---
 drivers/mmc/card/mmc_test.c         |  13 +
 drivers/mmc/card/queue.c            | 332 ++++++++++------
 drivers/mmc/card/queue.h            |  35 +-
 drivers/mmc/core/core.c             |  18 +-
 drivers/mmc/core/host.c             |   2 +
 drivers/mmc/core/host.h             |   2 -
 drivers/mmc/core/mmc.c              |  43 ++-
 drivers/mmc/core/mmc_ops.c          |  27 ++
 drivers/mmc/host/sdhci-acpi.c       |   2 +-
 drivers/mmc/host/sdhci-pci-core.c   |   2 +-
 include/linux/mmc/card.h            |   9 +
 include/linux/mmc/core.h            |   5 +
 include/linux/mmc/host.h            |   4 +-
 include/linux/mmc/mmc.h             |  17 +
 16 files changed, 1046 insertions(+), 204 deletions(-)


Regards
Adrian