[dm-devel] [PATCH v2 0/3] Historical Service Time Path Selector

[Gabriel Krisman Bertazi]

Hi Mike,

Please find an updated version of HST integrating the change you
requested to also support BIO based multipath.  I hope you don't mind me
folding the function you implemented into patch 2.  If you prefer, I can
integrate a patch you provide into the series.

One interesting data point is that the selection performance on
BIO-based is worse when compared to request-based.  I tested a bit and I
believe the reason is that the paths are more sticky because the bucket
is too large, and it takes longer for HST to detect differences.  By
changing the bucket_size indirectly through the bucket_shift, the
bio-based multipath performance improved, but I'm not sure this is a
knob we want to expose to users.  For now, please consider the patches
below, for review.

By the way, the exercise to support bio-based mpath uncovered the mpath
initialization bug that I fixed in the previous patch I sent today, so
it was worth it.

Gabriel Krisman Bertazi (2):
  md: multipath: Encapsulate parameters passed to selectors
  md: multipath: Pass io_start_time to the path selector

Khazhismel Kumykov (1):
  md: Add Historical Service Time Path Selector

 drivers/md/Kconfig                      |  11 +
 drivers/md/Makefile                     |   1 +
 drivers/md/dm-historical-service-time.c | 561 ++++++++++++++++++++++++
 drivers/md/dm-mpath.c                   |  30 +-
 drivers/md/dm-path-selector.h           |   9 +-
 drivers/md/dm-queue-length.c            |   4 +-
 drivers/md/dm-service-time.c            |   8 +-
 drivers/md/dm.c                         |  10 +
 include/linux/device-mapper.h           |   2 +
 9 files changed, 623 insertions(+), 13 deletions(-)
 create mode 100644 drivers/md/dm-historical-service-time.c

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2.26.2