On Fri, 27 Apr 2012, Konstantin Khlebnikov wrote: > Andrew Morton wrote: > > On Thu, 26 Apr 2012 11:53:44 +0400 > > Konstantin Khlebnikov<khlebnikov@xxxxxxxxxx> wrote: > > > > > This patchset depends on Johannes Weiner's patch > > > "mm: memcg: count pte references from every member of the reclaimed > > > hierarchy". > > > > > > bloat-o-meter delta for patches 2..12 > > > > > > add/remove: 6/6 grow/shrink: 6/14 up/down: 4414/-4625 (-211) > > > > That's the sole effect and intent of the patchset? To save 211 bytes? I am surprised it's not more: it feels like more. > > This is almost last bunch of cleanups for lru_lock splitting, > code reducing is only nice side-effect. > Also this patchset removes many redundant lruvec relookups. > > Now mostly all page-to-lruvec translations are located at the same level > as zone->lru_lock locking. So lru-lock splitting patchset can something like > this: > > -zone = page_zone(page) > -spin_lock_irq(&zone->lru_lock) > -lruvec = mem_cgroup_page_lruvec(page) > +lruvec = lock_page_lruvec_irq(page) > > > > > > ... > > > > > > include/linux/memcontrol.h | 16 +-- > > > include/linux/mmzone.h | 14 ++ > > > mm/memcontrol.c | 33 +++-- > > > mm/mmzone.c | 14 ++ > > > mm/page_alloc.c | 8 - > > > mm/vmscan.c | 277 > > > ++++++++++++++++++++------------------------ > > > 6 files changed, 177 insertions(+), 185 deletions(-) > > > > If so, I'm not sure that it is worth the risk and effort? I'm pretty sure that it is worth the effort, and see very little risk. It's close to my "[PATCH 3/10] mm/memcg: add zone pointer into lruvec" posted 20 Feb (after Konstantin posted his set a few days earlier), which Kamezawa-san Acked with "I like this cleanup". But this goes a little further (e.g. 01/12 saving an arg by moving priority into sc, that's nice; and v2 05/12 removing update_isolated_counts(), great). Konstantin and I came independently to this simplification, or generalization, from zone to lruvec: we're confident that it is the right direction, that it's a good basis for further work. Certainly neither of us have yet posted numbers to justify per-memcg per-zone locking (and I expect split zone locking to need more justification than it's had); but we both think these patches are a worthwhile cleanup on their own. I don't think it was particularly useful to split this into all of 12 pieces! But never mind, that's a trivial detail, not worth undoing. There's a few by-the-by bits and pieces I liked in my version that are not here, but nothing important: if I care enough, I can always send a little cleanup afterwards. The only change I'd ask for is in the commit comment on 02/12: it puzzlingly says "page_zone()" where it means to say "lruvec_zone()". I think if I'd been doing 04/12, I'd have resented passing "zone" to shrink_page_list(), would have deleted its VM_BUG_ON, and used a page_zone() for ZONE_CONGESTED: but that's just me being mean. I've gone through and compared the result of these 12 against my own tree updated to next-20120427. We come out much the same: the only divergence which worried me was that my mem_cgroup_zone_lruvec() says IF (!memcg || mem_cgroup_disabled()) return &zone->lruvec; and although I'm sure I had a reason for adding that "!memcg || ", I cannot now see why. Maybe it was for some intermediate use that went away (but I mention it in the hope that Konstantin will double check). To each one of the 12 (with lruvec_zone in 02/12, and v2 of 05/12): Acked-by: Hugh Dickins <hughd@xxxxxxxxxx> -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>