On Sun, Apr 01, 2018 at 03:08:06PM +0300, Leon Romanovsky wrote:
> +int mlx5_cmd_alloc_memic(struct mlx5_memic *memic, phys_addr_t *addr,
> + u64 length, u32 alignment)
> +{
> + struct mlx5_core_dev *dev = memic->dev;
> + u64 num_memic_hw_pages = MLX5_CAP_DEV_MEM(dev, memic_bar_size)
> + >> PAGE_SHIFT;
> + u64 hw_start_addr = MLX5_CAP64_DEV_MEM(dev, memic_bar_start_addr);
> + u32 max_alignment = MLX5_CAP_DEV_MEM(dev, log_max_memic_addr_alignment);
> + u32 num_pages = DIV_ROUND_UP(length, PAGE_SIZE);
> + u32 out[MLX5_ST_SZ_DW(alloc_memic_out)] = {};
> + u32 in[MLX5_ST_SZ_DW(alloc_memic_in)] = {};
> + u32 mlx5_alignment;
> + u64 page_idx = 0;
> + int ret = 0;
> +
> + if (!length || (length & MLX5_MEMIC_ALLOC_SIZE_MASK))
> + return -EINVAL;
> +
> + /* mlx5 device sets alignment as 64*2^driver_value
> + * so normalizing is needed.
> + */
> + mlx5_alignment = (alignment < MLX5_MEMIC_BASE_ALIGN) ? 0 :
> + alignment - MLX5_MEMIC_BASE_ALIGN;
> + if (mlx5_alignment > max_alignment)
> + return -EINVAL;
> +
> + MLX5_SET(alloc_memic_in, in, opcode, MLX5_CMD_OP_ALLOC_MEMIC);
> + MLX5_SET(alloc_memic_in, in, range_size, num_pages * PAGE_SIZE);
> + MLX5_SET(alloc_memic_in, in, memic_size, length);
> + MLX5_SET(alloc_memic_in, in, log_memic_addr_alignment,
> + mlx5_alignment);
> +
> + do {
> + spin_lock(&memic->memic_lock);
> + page_idx = bitmap_find_next_zero_area(memic->memic_alloc_pages,
> + num_memic_hw_pages,
> + page_idx,
> + num_pages, 0);
> +
> + if (page_idx + num_pages <= num_memic_hw_pages)
> + bitmap_set(memic->memic_alloc_pages,
> + page_idx, num_pages);
> + else
> + ret = -ENOMEM;
So every memic allocation takes an entire BAR page even if there is
empty space in pages already assigned to the context?
Seems rather inefficient? Could be improved in followup patches.
> + spin_unlock(&memic->memic_lock);
> +
> + if (ret)
> + return ret;
> +
> + MLX5_SET64(alloc_memic_in, in, range_start_addr,
> + hw_start_addr + (page_idx * PAGE_SIZE));
> +
> + ret = mlx5_cmd_exec(dev, in, sizeof(in), out, sizeof(out));
> + if (ret) {
> + spin_lock(&memic->memic_lock);
> + bitmap_clear(memic->memic_alloc_pages,
> + page_idx, num_pages);
> + spin_unlock(&memic->memic_lock);
> +
> + if (ret == -EAGAIN) {
> + page_idx++;
> + continue;
> + }
> +
> + return ret;
> + }
> +
> + *addr = pci_resource_start(dev->pdev, 0) +
> + MLX5_GET64(alloc_memic_out, out, memic_start_addr);
> +
> + return ret;
> + } while (page_idx < num_memic_hw_pages);
> +
> + return ret;
This return/while/return construct is a pretty muddled bit of logic.
Should just be
while (page_idx < num_memic_hw_pages) {
..
return 0;
};
return -ENOMEM;
Jason
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