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authorMichal Hocko <mhocko@suse.cz>2011-03-23 16:42:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-03-23 19:46:32 -0700
commitdde79e005a769d800166687c9e00d50d93e411ff (patch)
treea38166f535b48063bd680deb64edbedf4395cfed
parent4be4489feae6da890765cc1bdc1af5e4f8c4b75f (diff)
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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. [hannes@cmpxchg.org: do not define unused free_page_cgroup() without memory hotplug] Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/page_cgroup.c58
1 files changed, 36 insertions, 22 deletions
diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
index 6c3f7a6..8e7577c 100644
--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -130,7 +130,38 @@ struct page *lookup_cgroup_page(struct page_cgroup *pc)
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;
+}
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+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);
+ }
+ }
+}
+#endif
+
static int __init_refok init_section_page_cgroup(unsigned long pfn)
{
struct page_cgroup *base, *pc;
@@ -147,17 +178,8 @@ static int __init_refok init_section_page_cgroup(unsigned long pfn)
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 +211,8 @@ void __free_page_cgroup(unsigned long pfn)
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,