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mm: memcontrol: avoid charge statistics churn during page migration

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Charge migration currently disables IRQs twice to update the charge
statistics for the old page and then again for the new page.

But migration is a seamless transition of a charge from one physical
page to another one of the same size, so this should be a non-event from
an accounting point of view.  Leave the statistics alone.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner 2014-08-08 14:19:33 -07:00 committed by Linus Torvalds
parent 3cbb01871e
commit 6abb5a867b
1 changed files with 10 additions and 25 deletions
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35
mm/memcontrol.c
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@ -2728,7 +2728,7 @@ static void unlock_page_lru(struct page *page, int isolated)
}
static void commit_charge(struct page *page, struct mem_cgroup *memcg,
unsigned int nr_pages, bool lrucare)
bool lrucare)
{
struct page_cgroup *pc = lookup_page_cgroup(page);
int isolated;
@ -2765,16 +2765,6 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg,
if (lrucare)
unlock_page_lru(page, isolated);
local_irq_disable();
mem_cgroup_charge_statistics(memcg, page, nr_pages);
/*
* "charge_statistics" updated event counter. Then, check it.
* Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
* if they exceeds softlimit.
*/
memcg_check_events(memcg, page);
local_irq_enable();
}
static DEFINE_MUTEX(set_limit_mutex);
@ -6460,12 +6450,17 @@ void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg,
if (!memcg)
return;
commit_charge(page, memcg, lrucare);
if (PageTransHuge(page)) {
nr_pages <<= compound_order(page);
VM_BUG_ON_PAGE(!PageTransHuge(page), page);
}
commit_charge(page, memcg, nr_pages, lrucare);
local_irq_disable();
mem_cgroup_charge_statistics(memcg, page, nr_pages);
memcg_check_events(memcg, page);
local_irq_enable();
if (do_swap_account && PageSwapCache(page)) {
swp_entry_t entry = { .val = page_private(page) };
@ -6651,7 +6646,6 @@ void mem_cgroup_uncharge_list(struct list_head *page_list)
void mem_cgroup_migrate(struct page *oldpage, struct page *newpage,
bool lrucare)
{
unsigned int nr_pages = 1;
struct page_cgroup *pc;
int isolated;
@ -6660,6 +6654,8 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage,
VM_BUG_ON_PAGE(!lrucare && PageLRU(oldpage), oldpage);
VM_BUG_ON_PAGE(!lrucare && PageLRU(newpage), newpage);
VM_BUG_ON_PAGE(PageAnon(oldpage) != PageAnon(newpage), newpage);
VM_BUG_ON_PAGE(PageTransHuge(oldpage) != PageTransHuge(newpage),
newpage);
if (mem_cgroup_disabled())
return;
@ -6677,12 +6673,6 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage,
VM_BUG_ON_PAGE(!(pc->flags & PCG_MEM), oldpage);
VM_BUG_ON_PAGE(do_swap_account && !(pc->flags & PCG_MEMSW), oldpage);
if (PageTransHuge(oldpage)) {
nr_pages <<= compound_order(oldpage);
VM_BUG_ON_PAGE(!PageTransHuge(oldpage), oldpage);
VM_BUG_ON_PAGE(!PageTransHuge(newpage), newpage);
}
if (lrucare)
lock_page_lru(oldpage, &isolated);
@ -6691,12 +6681,7 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage,
if (lrucare)
unlock_page_lru(oldpage, isolated);
local_irq_disable();
mem_cgroup_charge_statistics(pc->mem_cgroup, oldpage, -nr_pages);
memcg_check_events(pc->mem_cgroup, oldpage);
local_irq_enable();
commit_charge(newpage, pc->mem_cgroup, nr_pages, lrucare);
commit_charge(newpage, pc->mem_cgroup, lrucare);
}
/*