From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johannes Weiner Subject: [patch] mm: memcontrol: avoid charge statistics churn during page migration Date: Mon, 4 Aug 2014 16:34:29 -0400 Message-ID: <1407184469-20741-1-git-send-email-hannes@cmpxchg.org> Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=cmpxchg.org; s=zene; h=Message-Id:Date:Subject:Cc:To:From; bh=zjP1qHHiadKSLuHqVznP1D67NSMu8sLH935ugbvFbZY=; b=DYNTDe7FIlzfyUwL0UkXGAIJuDJIPKxRT38ElP4vTH+dzK32Md58UwA9H40ZID4Wfoz9gPgdxLQQqfXiXBZEMwAkXK98kmfOZD/EK80RPTQyW706LtTNal9H+uHB+wn3E1jdKnXb5/cDjLIn0tSrlQmhkqk6eybaKteb8ILYUjI=; Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Andrew Morton Cc: Michal Hocko , Hugh Dickins , linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org 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 seemless 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 --- mm/memcontrol.c | 35 ++++++++++------------------------- 1 file changed, 10 insertions(+), 25 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 475ecadd9646..8d65dadeec1b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -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); } /* -- 2.0.3