Re: [PATCH 3/3] virtio_ring: unify direct/indirect code paths.

Paolo Bonzini
2014-09-05T10:55:37Z

Il 03/09/2014 06:29, Rusty Russell ha scritto:
> + desc = kmalloc(total_sg * sizeof(struct vring_desc), gfp);
> + if (!desc)
> + return NULL;
>
> - return head;
> + for (i = 0; i < total_sg; i++)
> + desc[i].next = i+1;
> + return desc;
> }

Would it make sense to keep a cache of a few (say) 8- or 16-element
indirect descriptors? You'd only have to do this ugly (and slowish) for
loop on the first allocation.

Also, since this is mostly an aesthetic patch,

> + if (indirect)
> + vq->free_head = vq->vring.desc[head].next;
> + else
> + vq->free_head = i;

I'd move the indirect case above, where the vring.desc[head] is actually
allocated.

Paolo