On Tue, Jan 12, 2021 at 12:38:34PM -0800, Nadav Amit wrote: > > On Jan 12, 2021, at 11:56 AM, Yu Zhao <yuzhao@xxxxxxxxxx> wrote: > > On Tue, Jan 12, 2021 at 11:15:43AM -0800, Nadav Amit wrote: > >> I will send an RFC soon for per-table deferred TLB flushes tracking. > >> The basic idea is to save a generation in the page-struct that tracks > >> when deferred PTE change took place, and track whenever a TLB flush > >> completed. In addition, other users - such as mprotect - would use > >> the tlb_gather interface. > >> > >> Unfortunately, due to limited space in page-struct this would only > >> be possible for 64-bit (and my implementation is only for x86-64). > > > > I don't want to discourage you but I don't think this would end up > > well. PPC doesn't necessarily follow one-page-struct-per-table rule, > > and I've run into problems with this before while trying to do > > something similar. > > Discourage, discourage. Better now than later. > > It will be relatively easy to extend the scheme to be per-VMA instead of > per-table for architectures that prefer it this way. It does require > TLB-generation tracking though, which Andy only implemented for x86, so I > will focus on x86-64 right now. Can you remind me of what we're missing on arm64 in this area, please? I'm happy to help get this up and running once you have something I can build on. Will
