On Wed, Apr 02, 2014 at 03:33:48PM +0400, Pavel Emelyanov wrote: ... > >> > >> But you'd have to be insane to care about NUMA balancing on 32-bit, > >> even with PAE. So restricting it to x86-64 and using the high bits (I > >> think bits 52-62 are all available to SW) sounds fine to me. > >> > >> Same goes for soft-dirty. I think it's fine if we say that you won't > >> have soft-dirty with a 32-bit kernel. Even with PAE. > > > > Well, at the moment we use soft-dirty for x86-64 only in criu but there > > were plans to implement complete 32bit support as well. While personally > > I don't mind dropping soft-dirty for non x86-64 case, I would like > > to hear Pavel's opinion, Pavel? > > We (Parallels) don't have plans on C/R on 32-bit kernels, but I speak only > for Parallels. However, people I know who need 32-bit C/R use ARM :) OK, since it's x86 specific I can prepare patch for dropping softdirty on x86-32 (this will release ugly macros in file mapping a bit but not that significantly). Guys, while looking into how to re-define _PAGE bits for case where present bit is dropped I though about the form like #define _PAGE_BIT_FILE (_PAGE_BIT_PRESENT + 1) /* _PAGE_BIT_RW */ #define _PAGE_BIT_NUMA (_PAGE_BIT_PRESENT + 2) /* _PAGE_BIT_USER */ #define _PAGE_BIT_PROTNONE (_PAGE_BIT_PRESENT + 3) /* _PAGE_BIT_PWT */ and while _PAGE_BIT_FILE case should work (as well as swap pages), I'm not that sure about the numa and protnone case. I fear there are some code paths which depends on the former bits positions -- ie when PAGE_BIT_PROTNONE = _PAGE_BIT_NUMA = _PAGE_BIT_GLOBAL. One of the _PAGE_BIT_GLOBAL user is the page attributes code. It seems to always check _PAGE_BIT_PRESENT together with _PAGE_BIT_GLOBAL, so if _PAGE_BIT_PROTNONE get redefined to a new value it should not fail. Thus main concern is protnone + numa code, which I must admit I don't know well enough yet. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>