# Re: \[PATCH 2/2\] virtio-blk: set NUMA affinity for a tagset

- From: Leon Romanovsky \<leon@kernel.org\>
- Date: 2021-09-27 11:34:20 
- List: virtualization
- Page: https://ratatoskr.run/virtualization/2021/09/6405657
- Thread: https://ratatoskr.run/kvm/2021/09/6405648/t.md

```text
On Sun, Sep 26, 2021 at 05:55:18PM +0300, Max Gurtovoy wrote:
> To optimize performance, set the affinity of the block device tagset
> according to the virtio device affinity.
> 
> Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
> ---
>  drivers/block/virtio_blk.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 9b3bd083b411..1c68c3e0ebf9 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -774,7 +774,7 @@ static int virtblk_probe(struct virtio_device *vdev)
>  	memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
>  	vblk->tag_set.ops = &virtio_mq_ops;
>  	vblk->tag_set.queue_depth = queue_depth;
> -	vblk->tag_set.numa_node = NUMA_NO_NODE;
> +	vblk->tag_set.numa_node = virtio_dev_to_node(vdev);

I afraid that by doing it, you will increase chances to see OOM, because
in NUMA_NO_NODE, MM will try allocate memory in whole system, while in
the latter mode only on specific NUMA which can be depleted.

Thanks

>  	vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
>  	vblk->tag_set.cmd_size =
>  		sizeof(struct virtblk_req) +
> -- 
> 2.18.1
> 
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```