On Sun 13-09-20 22:44:52, Waiman Long wrote: > The swap page counter is v2 only while memsw is v1 only. As v1 and v2 > controllers cannot be active at the same time, there is no point to keep > both swap and memsw page counters in mem_cgroup. The previous patch has > made sure that memsw page counter is updated and accessed only when in > v1 code paths. So it is now safe to alias the v1 memsw page counter to v2 > swap page counter. This saves 14 long's in the size of mem_cgroup. This > is a saving of 112 bytes for 64-bit archs.
I didn't realize that page_counter is so large. > While at it, also document which page counters are used in v1 and/or v2. > > Signed-off-by: Waiman Long <[email protected]> Acked-by: Michal Hocko <[email protected]> > --- > include/linux/memcontrol.h | 13 ++++++++----- > mm/memcontrol.c | 3 --- > 2 files changed, 8 insertions(+), 8 deletions(-) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index d0b036123c6a..6ef4a552e09d 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -215,13 +215,16 @@ struct mem_cgroup { > struct mem_cgroup_id id; > > /* Accounted resources */ > - struct page_counter memory; > - struct page_counter swap; > + struct page_counter memory; /* Both v1 & v2 */ > + > + union { > + struct page_counter swap; /* v2 only */ > + struct page_counter memsw; /* v1 only */ > + }; > > /* Legacy consumer-oriented counters */ > - struct page_counter memsw; > - struct page_counter kmem; > - struct page_counter tcpmem; > + struct page_counter kmem; /* v1 only */ > + struct page_counter tcpmem; /* v1 only */ > > /* Range enforcement for interrupt charges */ > struct work_struct high_work; > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index ca36bed588d1..188901f3a3db 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -5281,13 +5281,11 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state > *parent_css) > memcg->use_hierarchy = true; > page_counter_init(&memcg->memory, &parent->memory); > page_counter_init(&memcg->swap, &parent->swap); > - page_counter_init(&memcg->memsw, &parent->memsw); > page_counter_init(&memcg->kmem, &parent->kmem); > page_counter_init(&memcg->tcpmem, &parent->tcpmem); > } else { > page_counter_init(&memcg->memory, NULL); > page_counter_init(&memcg->swap, NULL); > - page_counter_init(&memcg->memsw, NULL); > page_counter_init(&memcg->kmem, NULL); > page_counter_init(&memcg->tcpmem, NULL); > /* > @@ -5416,7 +5414,6 @@ static void mem_cgroup_css_reset(struct > cgroup_subsys_state *css) > > page_counter_set_max(&memcg->memory, PAGE_COUNTER_MAX); > page_counter_set_max(&memcg->swap, PAGE_COUNTER_MAX); > - page_counter_set_max(&memcg->memsw, PAGE_COUNTER_MAX); > page_counter_set_max(&memcg->kmem, PAGE_COUNTER_MAX); > page_counter_set_max(&memcg->tcpmem, PAGE_COUNTER_MAX); > page_counter_set_min(&memcg->memory, 0); > -- > 2.18.1 -- Michal Hocko SUSE Labs
