From: Dongli Zhang Date: Wed, 27 Mar 2019 10:36:34 +0000 (+0800) Subject: virtio-blk: limit number of hw queues by nr_cpu_ids X-Git-Tag: v4.19.42~22 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0e8e67b8147fbcdd2d858c5f4c82297e12565e3d;p=platform%2Fkernel%2Flinux-rpi.git 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 Signed-off-by: Dongli Zhang Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 23752dc..dd64f58 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -446,6 +446,8 @@ static int init_vq(struct virtio_blk *vblk) if (err) num_vqs = 1; + num_vqs = min_t(unsigned int, nr_cpu_ids, num_vqs); + vblk->vqs = kmalloc_array(num_vqs, sizeof(*vblk->vqs), GFP_KERNEL); if (!vblk->vqs) return -ENOMEM;