On Tue 20-09-11 10:45:53, Johannes Weiner wrote: > On Mon, Sep 19, 2011 at 02:53:33PM +0200, Michal Hocko wrote: > > Hi, > > > > On Mon 12-09-11 12:57:18, Johannes Weiner wrote: > > > Memory control groups are currently bolted onto the side of > > > traditional memory management in places where better integration would > > > be preferrable. To reclaim memory, for example, memory control groups > > > maintain their own LRU list and reclaim strategy aside from the global > > > per-zone LRU list reclaim. But an extra list head for each existing > > > page frame is expensive and maintaining it requires additional code. > > > > > > This patchset disables the global per-zone LRU lists on memory cgroup > > > configurations and converts all its users to operate on the per-memory > > > cgroup lists instead. As LRU pages are then exclusively on one list, > > > this saves two list pointers for each page frame in the system: > > > > > > page_cgroup array size with 4G physical memory > > > > > > vanilla: [ 0.000000] allocated 31457280 bytes of page_cgroup > > > patched: [ 0.000000] allocated 15728640 bytes of page_cgroup > > > > > > At the same time, system performance for various workloads is > > > unaffected: > > > > > > 100G sparse file cat, 4G physical memory, 10 runs, to test for code > > > bloat in the traditional LRU handling and kswapd & direct reclaim > > > paths, without/with the memory controller configured in > > > > > > vanilla: 71.603(0.207) seconds > > > patched: 71.640(0.156) seconds > > > > > > vanilla: 79.558(0.288) seconds > > > patched: 77.233(0.147) seconds > > > > > > 100G sparse file cat in 1G memory cgroup, 10 runs, to test for code > > > bloat in the traditional memory cgroup LRU handling and reclaim path > > > > > > vanilla: 96.844(0.281) seconds > > > patched: 94.454(0.311) seconds > > > > > > 4 unlimited memcgs running kbuild -j32 each, 4G physical memory, 500M > > > swap on SSD, 10 runs, to test for regressions in kswapd & direct > > > reclaim using per-memcg LRU lists with multiple memcgs and multiple > > > allocators within each memcg > > > > > > vanilla: 717.722(1.440) seconds [ 69720.100(11600.835) majfaults ] > > > patched: 714.106(2.313) seconds [ 71109.300(14886.186) majfaults ] > > > > > > 16 unlimited memcgs running kbuild, 1900M hierarchical limit, 500M > > > swap on SSD, 10 runs, to test for regressions in hierarchical memcg > > > setups > > > > > > vanilla: 2742.058(1.992) seconds [ 26479.600(1736.737) majfaults ] > > > patched: 2743.267(1.214) seconds [ 27240.700(1076.063) majfaults ] > > > > I guess you want to have this in the first patch to have it for > > reference once it gets to the tree, right? I have no objections but it > > seems unrelated to the patch and so it might be confusing a bit. I > > haven't seen other patches in the series so there is probably no better > > place to put this. > > Andrew usually hand-picks what's of long-term interest from the series > description and puts it in the first patch. I thought I'd save him > the trouble. Understood [...] > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > > index b76011a..912c7c7 100644 > > > --- a/mm/memcontrol.c > > > +++ b/mm/memcontrol.c > > > @@ -781,83 +781,75 @@ struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm) > > > return memcg; > > > } > > > > > > -/* The caller has to guarantee "mem" exists before calling this */ > > > > Shouldn't we have a similar comment that we have to keep a reference to > > root if non-NULL. A mention about remember parameter and what is it used > > for (hierarchical reclaim) would be helpful as well. > > The only thing that dictates the lifetime of a memcg is its reference > count, so having a reference count while operating on a memecg is not > even a question for all existing memcg-internal callsites. Fair enough. > > But I did, in fact, add kernel-doc style documentation to > mem_cgroup_iter() when it becomes a public interface in 5/11. Can you > take a look and tell me whether you are okay with that? OK, I will comment on that patch once I get to it. [...] Thanks! -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- 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>