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authorKeith Busch <keith.busch@intel.com>2015-12-17 17:08:14 -0700
committerJens Axboe <axboe@fb.com>2016-02-09 12:42:17 -0700
commit868f2f0b72068a097508b6e8870a8950fd8eb7ef (patch)
treef88aed0e80d7b08c7a7907d8bcf4ff6df0150b66 /include/linux/blk-mq.h
parent3984aa55204e2c3f423a70b013c44c64261788df (diff)
blk-mq: dynamic h/w context count
The hardware's provided queue count may change at runtime with resource provisioning. This patch allows a block driver to alter the number of h/w queues available when its resource count changes. The main part is a new blk-mq API to request a new number of h/w queues for a given live tag set. The new API freezes all queues using that set, then adjusts the allocated count prior to remapping these to CPUs. The bulk of the rest just shifts where h/w contexts and all their artifacts are allocated and freed. The number of max h/w contexts is capped to the number of possible cpus since there is no use for more than that. As such, all pre-allocated memory for pointers need to account for the max possible rather than the initial number of queues. A side effect of this is that the blk-mq will proceed successfully as long as it can allocate at least one h/w context. Previously it would fail request queue initialization if less than the requested number was allocated. Signed-off-by: Keith Busch <keith.busch@intel.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Jon Derrick <jonathan.derrick@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'include/linux/blk-mq.h')
-rw-r--r--include/linux/blk-mq.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 7fc9296b5742..15a73d49fd1d 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -244,6 +244,8 @@ void blk_mq_freeze_queue(struct request_queue *q);
void blk_mq_unfreeze_queue(struct request_queue *q);
void blk_mq_freeze_queue_start(struct request_queue *q);
+void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues);
+
/*
* Driver command data is immediately after the request. So subtract request
* size to get back to the original request, add request size to get the PDU.