On Tue, May 06, 2014 at 09:28:07AM -0700, H. Peter Anvin wrote: > On 04/25/2014 01:10 AM, Cyrill Gorcunov wrote: > > Tracking dirty status on 2 level pages requires very ugly macros > > and taking into account how old the machines who can operate > > without PAE mode only are, lets drop soft dirty tracker from > > them for code simplicity (note I can't drop all the macros > > from 2 level pages by now since _PAGE_BIT_PROTNONE and > > _PAGE_BIT_FILE are still used even without tracker). > > > > Linus proposed to completely rip off softdirty support on > > x86-32 (even with PAE) and since for CRIU we're not planning > > to support native x86-32 mode, lets do that. > > > > (Softdirty tracker is relatively new feature which mostly used > > by CRIU so I don't expect if such API change would cause problems > > on userspace). > > I have to wonder which one is more likely to actually matter on whatever > legacy 32-bit are going to remain. This pretty much comes down to what > kind of advanced features are going to matter in deep embedded > applications in the future: checkpoint/restart or NUMA. My guess is > that it is actually checkpoint/restart... > > How much does it actually simplify to leave this feature in for PAE? I > could care less about non-PAE... NX has pretty much killed that off cold.
At the current state -- not much I would say. Initially the idea was to drop x86-32 and use page-soft-dirty-bit (ie 11) inside swap entries dropping off page-swap-soft-dirty bit completely, this would simplify all the things but eventually I realized that if I do so the number of maximum swap entries will get more shrinked which is inacceptable I think. Thus, currently (ie even with this patches) we can work on x86-32+PAE but desided to drop x86-32 completely to simplify things in future. Peter, deep embedded applications I guess would be working on systems with really small amount of memory installed in a system I suppose and I doubt if they would need c/r? If we deside to leave x86-32+PAE then don't apply this patch, I will need to update it, (The first patch is safe to apply anyway). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
