tree 614cc76c04c6a7e17278839d28b3e26608a63f82
parent e814e71ba4a6e1d7509b0f4b1928365ea650cace
author Jens Axboe <axboe@fb.com> 1400702475 -0600
committer Jens Axboe <axboe@fb.com> 1400702475 -0600

blk-mq: save memory by freeing requests on unused hardware queues

Depending on the topology of the machine and the number of queues
exposed by a device, we can end up in a situation where some of
the hardware queues are unused (as in, they don't map to any
software queues). For this case, free up the memory used by the
request map, as we will not use it. This can be a substantial
amount of memory, depending on the number of queues vs CPUs and
the queue depth of the device.

Signed-off-by: Jens Axboe <axboe@fb.com>