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| author | Dongli Zhang <dongli.zhang@oracle.com> | 2019-03-27 18:36:34 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-04-10 08:18:24 -0600 |
| commit | bf348f9b78d413e75bb079462751a1d86b6de36c (patch) | |
| tree | ff62f039df5b908c1c02f8d4074e38ac3b8b9f2a /Documentation/target | |
| parent | eed47d19d9362bdd958e4ab56af480b9dbf6b2b6 (diff) | |
| download | linux-bf348f9b78d413e75bb079462751a1d86b6de36c.tar.bz2 | |
virtio-blk: limit number of hw queues by nr_cpu_ids
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>
Diffstat (limited to 'Documentation/target')
0 files changed, 0 insertions, 0 deletions