Il giorno 05 dic 2016, alle ore 19:26, Jens Axboe [off-list ref] ha =

scritto:

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Version 2 of the hack/patchset, that enables blk-mq to use the legacy
IO schedulers with single queue devices. Original posting is here:
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https://marc.info/?l=3Dlinux-block&m=3D148073493203664&w=3D2
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You can also found this version in the following git branch:
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git://git.kernel.dk/linux-block blk-mq-legacy-sched.2
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and new developments/fixes will happen in the 'blk-mq-legacy-sched'
branch.
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Hi Jens,
while running some tests, the system hung after a while.

If I'm not mistaken, the above branches contain a (modified) 4.9-rc1.
Maybe instability follows from that?  I have tried a rebase, but
resulting conflicts are non-trivial (for me) to solve.

Meanwhile, if you deem it useful, I can provide you with the oops
message, as I catch it.

As a secondary issue, iostat always reports 0 MB/s for both reads and
writes, while tps are non null.

Thanks,
Paolo

Changes since v1:
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- Remove the default 'deadline' hard wiring, and provide Kconfig
 entries to set the blk-mq scheduler. This now works like for legacy
 devices.
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- Rename blk_use_mq_path() to blk_use_sched_path() to make it more
 clear. Suggested by Johannes Thumshirn.
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- Fixup a spot where we did not use the accessor function to determine
 what path to use.
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- Flush mq software queues, even if IO scheduler managed. This should
 make paths work that are MQ aware, and using only MQ interfaces.
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- Cleanup free path of MQ request.
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- Account when IO was queued to a hardware context, similarly to the
 regular MQ path.
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- Add BLK_MQ_F_NO_SCHED flag, so that drivers can explicitly ask for
 no scheduling on a queue. Add this for NVMe admin queues.
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- Kill BLK_MQ_F_SCHED, since we now have Kconfig entries for setting
 the desired IO scheduler.
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- Fix issues with live scheduler switching through sysfs. Should now
 be solid, even with lots of IO running on the device.
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- Drop null_blk and SCSI changes, not needed anymore.
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block/Kconfig.iosched   |   29 ++++
block/blk-core.c        |   77 ++++++-----
block/blk-exec.c        |   12 +
block/blk-flush.c       |   40 +++--
block/blk-merge.c       |    5=20
block/blk-mq.c          |  332 =

+++++++++++++++++++++++++++++++++++++++++++++---

block/blk-mq.h          |    1=20
block/blk-sysfs.c       |    2=20
block/blk.h             |   16 ++
block/cfq-iosched.c     |   22 ++-
block/elevator.c        |  125 ++++++++++++------
drivers/nvme/host/pci.c |    1=20
include/linux/blk-mq.h  |    1=20
include/linux/blkdev.h  |    2=20
14 files changed, 555 insertions(+), 110 deletions(-)
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