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authorMing Lei <ming.lei@redhat.com>2018-04-08 17:48:08 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-04-19 08:55:10 +0200
commit645840a176122196c33e9eadcee5f1115e918357 (patch)
parent01e12511b9e905539e245a17c0af6ded0fa1fb94 (diff)
blk-mq: don't keep offline CPUs mapped to hctx 0
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>
1 files changed, 0 insertions, 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;