在 2021/8/5 下午8:34, Yongji Xie 写道:
My main point, though, is that if you've already got something else
keeping track of the actual addresses, then the way you're using an
iova_domain appears to be something you could do with a trivial bitmap
allocator. That's why I don't buy the efficiency argument. The main
design points of the IOVA allocator are to manage large address spaces
while trying to maximise spatial locality to minimise the underlying
pagetable usage, and allocating with a flexible limit to support
multiple devices with different addressing capabilities in the same
address space. If none of those aspects are relevant to the use-case -
which AFAICS appears to be true here - then as a general-purpose
resource allocator it's rubbish and has an unreasonably massive memory
overhead and there are many, many better choices.
OK, I get your point. Actually we used the genpool allocator in the
early version. Maybe we can fall back to using it.
I think maybe you can share some perf numbers to see how much
alloc_iova_fast() can help.
Thanks
