Re: [PATCH v4 0/8] Allow dynamic allocation of software IO TLB bounce buffers

[Christoph Hellwig]

Just to add a highlevel comment here after I feel like I need a little
more time to review the guts.

I'm still pretty concerned about the extra list that needs to be
consulted in is_swiotlb_buffer, but I can't really think of
anything better.  Maybe an xarray has better cache characteristics,
but that one requires even more allocations in the low-level dma map
path.

One thing I'd like to see for the next version is to make the
new growing code a config option at least for now.  It is a pretty
big change of the existing swiotlb behavior, and I want people to opt
into it conciously.  Maybe we can drop the option again after a few
years once everything has settled.