On Tue 01-03-11 16:05:50, Andrew Morton wrote: > On Mon, 28 Feb 2011 11:09:20 +0100 > Michal Hocko <mhocko@xxxxxxx> wrote: > > > Hi Andrew, > > could you consider the patch bellow, please? > > The patch was discussed at https://lkml.org/lkml/2011/2/23/232 [...] > This conflicts with > memcg-remove-direct-page_cgroup-to-page-pointer.patch, which did I have based my patch on top of the current Linus tree. Sorry about that. Here is the patch rebased on top of the mmotm (2011-02-10-16-26). The patch passes also checkpatch now. --- >From 7e5b1e7043605891dacd9e32f19985bc675292f5 Mon Sep 17 00:00:00 2001 From: Michal Hocko <mhocko@xxxxxxx> Date: Thu, 24 Feb 2011 11:25:44 +0100 Subject: [PATCH 1/2] page_cgroup: Reduce allocation overhead for page_cgroup array for CONFIG_SPARSEMEM Currently we are allocating a single page_cgroup array per memory section (stored in mem_section->base) when CONFIG_SPARSEMEM is selected. This is correct but memory inefficient solution because the allocated memory (unless we fall back to vmalloc) is not kmalloc friendly: - 32b - 16384 entries (20B per entry) fit into 327680B so the 524288B slab cache is used - 32b with PAE - 131072 entries with 2621440B fit into 4194304B - 64b - 32768 entries (40B per entry) fit into 2097152 cache This is ~37% wasted space per memory section and it sumps up for the whole memory. On a x86_64 machine it is something like 6MB per 1GB of RAM. We can reduce the internal fragmentation by using alloc_pages_exact which allocates PAGE_SIZE aligned blocks so we will get down to <4kB wasted memory per section which is much better. We still need a fallback to vmalloc because we have no guarantees that we will have a continuous memory of that size (order-10) later on during the hotplug events. Signed-off-by: Michal Hocko <mhocko@xxxxxxx> CC: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx> CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Index: linux-2.6.38-rc4/mm/page_cgroup.c =================================================================== --- linux-2.6.38-rc4.orig/mm/page_cgroup.c 2011-03-02 10:42:32.000000000 +0100 +++ linux-2.6.38-rc4/mm/page_cgroup.c 2011-03-02 10:59:41.000000000 +0100 @@ -130,7 +130,36 @@ struct page *lookup_cgroup_page(struct p return page; } -/* __alloc_bootmem...() is protected by !slab_available() */ +static void *__init_refok alloc_page_cgroup(size_t size, int nid) +{ + void *addr = NULL; + + addr = alloc_pages_exact(size, GFP_KERNEL | __GFP_NOWARN); + if (addr) + return addr; + + if (node_state(nid, N_HIGH_MEMORY)) + addr = vmalloc_node(size, nid); + else + addr = vmalloc(size); + + return addr; +} + +static void free_page_cgroup(void *addr) +{ + if (is_vmalloc_addr(addr)) { + vfree(addr); + } else { + struct page *page = virt_to_page(addr); + if (!PageReserved(page)) { /* Is bootmem ? */ + size_t table_size = + sizeof(struct page_cgroup) * PAGES_PER_SECTION; + free_pages_exact(addr, table_size); + } + } +} + static int __init_refok init_section_page_cgroup(unsigned long pfn) { struct page_cgroup *base, *pc; @@ -147,17 +176,8 @@ static int __init_refok init_section_pag nid = page_to_nid(pfn_to_page(pfn)); table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION; - VM_BUG_ON(!slab_is_available()); - if (node_state(nid, N_HIGH_MEMORY)) { - base = kmalloc_node(table_size, - GFP_KERNEL | __GFP_NOWARN, nid); - if (!base) - base = vmalloc_node(table_size, nid); - } else { - base = kmalloc(table_size, GFP_KERNEL | __GFP_NOWARN); - if (!base) - base = vmalloc(table_size); - } + base = alloc_page_cgroup(table_size, nid); + /* * The value stored in section->page_cgroup is (base - pfn) * and it does not point to the memory block allocated above, @@ -189,16 +209,8 @@ void __free_page_cgroup(unsigned long pf if (!ms || !ms->page_cgroup) return; base = ms->page_cgroup + pfn; - if (is_vmalloc_addr(base)) { - vfree(base); - ms->page_cgroup = NULL; - } else { - struct page *page = virt_to_page(base); - if (!PageReserved(page)) { /* Is bootmem ? */ - kfree(base); - ms->page_cgroup = NULL; - } - } + free_page_cgroup(base); + ms->page_cgroup = NULL; } int __meminit online_page_cgroup(unsigned long start_pfn, -- 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@xxxxxxxxxx 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>