2014-12-01 13:35 GMT+03:00 Hugh Dickins <hughd@xxxxxxxxxx>: > On Fri, 14 Nov 2014, Timofey Titovets wrote: > >> Good time of day List, >> this tiny series of patches implement feature for auto deduping all anonymous memory. >> mark_new_vma - new ksm sysfs interface >> Every time then new vma created and mark_new_vma set to 1, then will be vma marked as VM_MERGEABLE and added to ksm queue. >> This can produce small overheads >> (I have not catch any problems or slowdown) >> >> This is useful for: >> Android (CM) devs which implement ksm support with patching system. >> Users of tiny pc. >> Servers what not use KVM but use something very releated, like containers. >> >> Can be pulled from: >> https://github.com/Nefelim4ag/linux.git ksm_improvements >> >> For tests: >> I have tested it and it working very good. For testing apply it and enable ksm: >> echo 1 | sudo tee /sys/kernel/mm/ksm/run >> This show how much memory saved: >> echo $[$(cat /sys/kernel/mm/ksm/pages_shared)*$(getconf PAGE_SIZE)/1024 ]KB >> >> On my system i save ~1% of memory 26 Mb/2100 Mb (deduped)/(used) >> >> v2: >> Added Kconfig for control default value of mark_new_vma >> Added sysfs interface for control mark_new_vma >> Splitted in several patches >> >> v3: >> Documentation for ksm changed for clarify new cha >> >> Timofey Titovets (4): >> KSM: Add auto flag new VMA as VM_MERGEABLE >> KSM: Add to sysfs - mark_new_vma >> KSM: Add config to control mark_new_vma >> KSM: mark_new_vma added to Documentation. >> >> Documentation/vm/ksm.txt | 7 +++++++ >> include/linux/ksm.h | 39 +++++++++++++++++++++++++++++++++++++++ >> mm/Kconfig | 7 +++++++ >> mm/ksm.c | 39 ++++++++++++++++++++++++++++++++++++++- >> mm/mmap.c | 17 +++++++++++++++++ >> 5 files changed, 108 insertions(+), 1 deletion(-) > > I welcome what you're trying to achieve with this, > but have a lot of issues with how you have gone about it. > > (I have my own patch to mm/mmap.c to achieve a similar effect, for > testing KSM: but looking through it again now, conclude that it's just > too hacky for others' eyes: I'd be glad to have something in the tree > that saves me from having to apply that hack in the future.) Where i can see your code? =) > Please reduce this to a single patch: I don't see anything gained, > but both our time wasted, from having it split into four. Sorry, fixed =-= > Please run scripts/checkpatch.pl over the result: it has quite a > few complaints; or you might prefer to do that afterwards... > > Please throw away all(?) of your changes to mm/mmap.c, and those > inlines in include/linux/ksm.h. KSM has a tradition of invading > the rest of mm as little as possible, and I'd like to keep to that > so far as we can (and others will want us to keep to that even more > than I do). > > Instead of trying to apply VM_MERGEABLE in assorted places > throughout mmap.c, you should instead be modifying ksm.c to > ignore VM_MERGEABLE and respect only its conditioning flags > when your option is set. (Looking through those conditioning > flags, I think the only one that actually matters internally > is probably VM_HUGETLB - having an anon_vma is in practice the > important criterion - but better that you continue to respect > those flags for now, rather than experimenting without them.) > > Then I think all you need is one hook somewhere to ensure that > every mm gets on KSM's mm_list (while your option is set), > instead of just those which call madvise(,,MADV_MERGEABLE). > Or does this approach not work for some reason? First of all, I am a kernel newbie and i can miss something, sorry if it happens. Ksm can't scan memory by itself. I'm not only mark page as VM_MERGEABLE, i call __ksm_enter for adding it to ksm mm_list. I already think about case where ksm scan all mm find marked with VM_MERGEABLE and add it to own mm_list: First its can slow down entire system as i think. But at now it does not matter. Second, really, i can't find global mm tree =_='' or something like it for add one to ksm. Can you specify where i can found it or may be i mistaking in somewhere? i must fix issue above before try modify ksm for ignore VM_MERGEABLE =\ > Please find some better naming: I suggest "all_mergeable" for > the tunable, and KSM_ALL_MERGEABLE for the config option (my hack > has an "allksm" boot option, but I think we can do without that). > Poor naming ("ksm_vma_add_new" was an mm operation) misled you into > putting hooks into quite unnecessary places (how would splitting a > vma require a change to the mm's MMF_MERGEABLE?). Thanks for idea, i renamed it. > Then we can look at the result of that; but be warned, as you can > see from the "speed" of my reply, I have no time to spare at present, > and few others are interested in KSM (perhaps that's an unfortunate > side-effect of our success in keeping it isolated from the rest of mm). > > Thanks, > Hugh Not a problem Hugh, thanks for reply. -- Have a nice day, Timofey. -- 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>