Hi, Eugenio,
Sorry for the super late response.
On Fri, Oct 29, 2021 at 08:35:22PM +0200, Eugenio Pérez wrote:
[...]
> +int iova_tree_alloc(IOVATree *tree, DMAMap *map, hwaddr iova_begin,
> + hwaddr iova_last)
> +{
> + struct IOVATreeAllocArgs args = {
> + .new_size = map->size,
> + .iova_begin = iova_begin,
> + .iova_last = iova_last,
> + };
> +
> + if (iova_begin == 0) {
> + /* Some devices does not like addr 0 */
> + iova_begin += qemu_real_host_page_size;
> + }
Any explanation of why zero is not welcomed?
It would be great if we can move this out of iova-tree.c, because that doesn't
look like a good place to, e.g. reference qemu_real_host_page_size, anyways.
The caller can simply pass in qemu_real_host_page_size as iova_begin when
needed (and I highly doubt it'll be a must for all iova-tree users..)
> +
> + assert(iova_begin < iova_last);
> +
> + /*
> + * Find a valid hole for the mapping
> + *
> + * Assuming low iova_begin, so no need to do a binary search to
> + * locate the first node.
> + *
> + * TODO: We can improve the search speed if we save the beginning and the
> + * end of holes, so we don't iterate over the previous saved ones.
> + *
> + * TODO: Replace all this with g_tree_node_first/next/last when available
> + * (from glib since 2.68). To do it with g_tree_foreach complicates the
> + * code a lot.
> + *
> + */
> + g_tree_foreach(tree->tree, iova_tree_alloc_traverse, &args);
> + if (!iova_tree_alloc_map_in_hole(&args)) {
> + /*
> + * 2nd try: Last iteration left args->right as the last DMAMap. But
> + * (right, end) hole needs to be checked too
> + */
> + iova_tree_alloc_args_iterate(&args, NULL);
> + if (!iova_tree_alloc_map_in_hole(&args)) {
> + return IOVA_ERR_NOMEM;
> + }
> + }
> +
> + map->iova = MAX(iova_begin,
> + args.hole_left ?
> + args.hole_left->iova + args.hole_left->size + 1 : 0);
> + return iova_tree_insert(tree, map);
> +}
Re the algorithm - I totally agree Jason's version is much better.
Thanks,
--
Peter Xu
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