From: Ming Lin <ming.l@xxxxxxxxxxx>
Please see patch 2 for detail bug description.
Say, on a machine with 8 CPUs, we create 6 io queues(blk-mq hw queues)
echo "transport=rdma,traddr=192.168.2.2,nqn=testiqn,nr_io_queues=6" \
> /dev/nvme-fabrics
Then actually only 4 hw queues were mapped to CPU sw queues.
HW Queue 1 <-> CPU 0,4
HW Queue 2 <-> CPU 1,5
HW Queue 3 <-> None
HW Queue 4 <-> CPU 2,6
HW Queue 5 <-> CPU 3,7
HW Queue 6 <-> None
Back to Jan 2016, I send a patch:
[PATCH] blk-mq: check if all HW queues are mapped to cpu
http://www.spinics.net/lists/linux-block/msg01038.html
It adds check code to blk_mq_update_queue_map().
But it seems too aggresive because it's not an error that some hw queues
were not mapped to sw queues.
So this series just add a new function blk_mq_hctx_mapped() to check
how many hw queues were mapped. And the driver(for example, nvme-rdma)
that cares about it will do the check.
Ming Lin (2):
blk-mq: add a function to return number of hw queues mapped
nvme-rdma: check the number of hw queues mapped
block/blk-mq.c | 15 +++++++++++++++
drivers/nvme/host/rdma.c | 11 +++++++++++
include/linux/blk-mq.h | 1 +
3 files changed, 27 insertions(+)
--
1.9.1
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