From commit 4b855ad37194 ("blk-mq: Create hctx for each present CPU),

blk-mq doesn't remap queue after CPU topo is changed, that said when some of these offline CPUs become online, they are still mapped to hctx 0, then hctx 0 may become the bottleneck of IO dispatch and completion.

This patch sets up the mapping from the beginning, and aligns to queue mapping for PCI device (blk_mq_pci_map_queues()).

Fixes: 4b855ad37194 ("blk-mq: Create hctx for each present CPU) Cc: Christian Borntraeger borntraeger@de.ibm.com Cc: Christoph Hellwig hch@lst.de Cc: Stefan Haberland sth@linux.vnet.ibm.com Cc: Keith Busch keith.busch@intel.com Cc: stable@vger.kernel.org Signed-off-by: Ming Lei ming.lei@redhat.com --- block/blk-mq-cpumap.c | 5 ----- 1 file changed, 5 deletions(-)

diff --git a/block/blk-mq-cpumap.c b/block/blk-mq-cpumap.c index 9f8cffc8a701..3eb169f15842 100644 --- a/block/blk-mq-cpumap.c +++ b/block/blk-mq-cpumap.c @@ -16,11 +16,6 @@

static int cpu_to_queue_index(unsigned int nr_queues, const int cpu) { - /* - * Non present CPU will be mapped to queue index 0. - */ - if (!cpu_present(cpu)) - return 0; return cpu % nr_queues; }