| commit | c301c5d382dd7f47042bb7631bea70a02dab7b0f | |
| author | Dongli Zhang <dongli.zhang@oracle.com> | |
| Wed, 27 Mar 2019 10:36:34 +0000 (27 18:36 +0800) | ||
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | |
| Fri, 10 May 2019 15:52:09 +0000 (10 17:52 +0200) | ||
| tree | 25f276d391398f86e963da28722bccf36dc721a5 | treesnapshot (tar.gz zip) |
| parent | 684a9e97ba19bfde873f245f8bb198625f9d3ba5 | commitdiff |
virtio-blk: limit number of hw queues by nr_cpu_ids
[ Upstream commit bf348f9b78d413e75bb079462751a1d86b6de36c ]
When tag_set->nr_maps is 1, the block layer limits the number of hw queues
by nr_cpu_ids. No matter how many hw queues are used by virtio-blk, as it
has (tag_set->nr_maps == 1), it can use at most nr_cpu_ids hw queues.
In addition, specifically for pci scenario, when the 'num-queues' specified
by qemu is more than maxcpus, virtio-blk would not be able to allocate more
than maxcpus vectors in order to have a vector for each queue. As a result,
it falls back into MSI-X with one vector for config and one shared for
queues.
Considering above reasons, this patch limits the number of hw queues used
by virtio-blk by nr_cpu_ids.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit bf348f9b78d413e75bb079462751a1d86b6de36c ]
When tag_set->nr_maps is 1, the block layer limits the number of hw queues
by nr_cpu_ids. No matter how many hw queues are used by virtio-blk, as it
has (tag_set->nr_maps == 1), it can use at most nr_cpu_ids hw queues.
In addition, specifically for pci scenario, when the 'num-queues' specified
by qemu is more than maxcpus, virtio-blk would not be able to allocate more
than maxcpus vectors in order to have a vector for each queue. As a result,
it falls back into MSI-X with one vector for config and one shared for
queues.
Considering above reasons, this patch limits the number of hw queues used
by virtio-blk by nr_cpu_ids.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| drivers/block/virtio_blk.c | diffblobblamehistory |