[PATCH v2 0/2] improve nvme quiesce time for large amount of namespaces

[Chao Leng]

This set improves the quiesce time when using a large set of
namespaces, which also improves I/O failover time in a multipath environment.

We improve for both non-blocking hctxs and blocking hctxs introducing
blk_mq_[un]quiesce_tagset which works on all request queues over a given
tagset in parallel (which is the case in nvme) for both tagset types (blocking
and non-blocking);

Changes from v1:
- improvement is based on tagset rather than namesapces

Chao Leng (2):
  blk-mq: add tagset quiesce interface
  nvme: use blk_mq_[un]quiesce_tagset

 block/blk-mq.c           | 75 ++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/nvme/host/core.c | 42 +++++++++------------------
 drivers/nvme/host/nvme.h |  2 +-
 include/linux/blk-mq.h   |  2 ++
 include/linux/blkdev.h   |  2 ++
 5 files changed, 93 insertions(+), 30 deletions(-)

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2.16.4