On 01.07.19 10:41, Michal Hocko wrote:

On Mon 27-05-19 13:11:50, David Hildenbrand wrote:

quoted

Let's factor out removing of memory block devices, which is only
necessary for memory added via add_memory() and friends that created
memory block devices. Remove the devices before calling
arch_remove_memory().

This finishes factoring out memory block device handling from
arch_add_memory() and arch_remove_memory().

OK, this makes sense again. Just a nit. Calling find_memory_block_by_id
for each memory block looks a bit suboptimal, especially when we are
removing consequent physical memblocks. I have to confess that I do not
know how expensive is the search and I also expect that there won't be
that many memblocks in the removed range anyway as large setups have
large memblocks.

The devices are not allocated sequentially, so there is no easy way to
look them up.

There is a comment for find_memory_block():

"For now, we have a linear search to go find the appropriate
memory_block corresponding to a particular phys_index. If this gets to
be a real problem, we can always use a radix tree or something here."

So if this becomes a problem, we need a separate data structure to speed
up the lookup. (IOW, this was already the same in the old code)

Thanks!

-- 

Thanks,

David / dhildenb