| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.14 45/49] blk-mq: dont keep offline CPUs mapped to hctx 0 | Date | Tue, 17 Apr 2018 17:59:24 +0200 |
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4.14-stable review patch. If anyone has any objections, please let me know.
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From: Ming Lei <ming.lei@redhat.com>
commit bffa9909a6b48d8ca3398dec601bc9162a4020c4 upstream.
>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()).
Cc: Stefan Haberland <sth@linux.vnet.ibm.com> Cc: Keith Busch <keith.busch@intel.com> Cc: stable@vger.kernel.org Fixes: 4b855ad37194 ("blk-mq: Create hctx for each present CPU) Tested-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- block/blk-mq-cpumap.c | 5 ----- 1 file changed, 5 deletions(-)
--- 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; }
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