Hi Linus, On Fri, Sep 03, 2021 at 12:08:03PM -0700, Linus Torvalds wrote: > On Fri, Sep 3, 2021 at 12:02 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > > > Was there a reason you chose to do it that way instead of having per-node > > i_mapping pointers? > > You can't have per-node i_mapping pointers without huge coherence issues. > > If you don't care about coherence, that's fine - but that has to be a > user-space decision (ie "I will just replicate this file"). > > You can't just have the kernel decide "I'll map this set of pages on > this node, and that other ser of pages on that other node", in case > there's MAP_SHARED things going on. > > Anyway, I think very fundamentally this is one of those things where > 99.9% of all people don't care, and DO NOT WANT the complexity. > > And the 0.1% that _does_ care really could and should do this in user > space, because they know they care. > > Asking the kernel to do complex things in critical core functions for > something that is very very rare and irrelevant to most people, and > that can and should just be done in user space for the people who care > is the wrong approach. > > Because the question here really should be "is this truly important, > and does this need kernel help because user space simply cannot do it > itself". > > And the answer is a fairly simple "no". Okay. Thanks for confirming this. Thanks Huang Shijie
