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Subject[RFC][PATCH 11/9] lazy lru free vector for memcg
Free page_cgroup from its LRU in batched manner.

When uncharge() is called, page is pushed ontto per-cpu vector and
removed from LRU. This is depends on increment-page-count-via-page-cgroup
patch. Because page_cgroup has refcnt to the page, we don't have to be
afraid that the page is reused while it's on vector.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

---
mm/memcontrol.c | 163 +++++++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 155 insertions(+), 8 deletions(-)

Index: mmtom-2.6.27-rc5+/mm/memcontrol.c
===================================================================
--- mmtom-2.6.27-rc5+.orig/mm/memcontrol.c
+++ mmtom-2.6.27-rc5+/mm/memcontrol.c
@@ -35,6 +35,7 @@
#include <linux/vmalloc.h>
#include <linux/mm_inline.h>
#include <linux/page_cgroup.h>
+#include <linux/cpu.h>

#include <asm/uaccess.h>

@@ -539,6 +540,120 @@ out:
return ret;
}

+
+#define MEMCG_PCPVEC_SIZE (8)
+struct memcg_percpu_vec {
+ int nr;
+ int limit;
+ struct mem_cgroup *hot_memcg;
+ struct mem_cgroup_per_zone *hot_mz;
+ struct page_cgroup *vec[MEMCG_PCPVEC_SIZE];
+};
+DEFINE_PER_CPU(struct memcg_percpu_vec, memcg_free_vec);
+
+static void
+__release_page_cgroup(struct memcg_percpu_vec *mpv)
+{
+ unsigned long flags;
+ struct mem_cgroup_per_zone *mz;
+ struct mem_cgroup *owner;
+ struct page_cgroup *pc;
+ struct page *freed[MEMCG_PCPVEC_SIZE];
+ int i, nr;
+
+ mz = mpv->hot_mz;
+ owner = mpv->hot_memcg;
+ spin_lock_irqsave(&mz->lru_lock, flags);
+ nr = mpv->nr;
+ for (i = nr - 1; i >= 0; i--) {
+ pc = mpv->vec[i];
+ VM_BUG_ON(PageCgroupUsed(pc));
+ __mem_cgroup_remove_list(mz, pc);
+ css_put(&owner->css);
+ freed[i] = pc->page;
+ pc->mem_cgroup = NULL;
+ }
+ mpv->nr = 0;
+ spin_unlock_irqrestore(&mz->lru_lock, flags);
+ for (i = nr - 1; i >= 0; i--)
+ put_page(freed[i]);
+}
+
+static void
+release_page_cgroup(struct mem_cgroup_per_zone *mz,struct page_cgroup *pc)
+{
+ struct memcg_percpu_vec *mpv;
+
+ mpv = &get_cpu_var(memcg_free_vec);
+ if (mpv->hot_mz != mz) {
+ if (mpv->nr > 0)
+ __release_page_cgroup(mpv);
+ mpv->hot_mz = mz;
+ mpv->hot_memcg = pc->mem_cgroup;
+ }
+ mpv->vec[mpv->nr++] = pc;
+ if (mpv->nr >= mpv->limit)
+ __release_page_cgroup(mpv);
+ put_cpu_var(memcg_free_vec);
+}
+
+static void page_cgroup_start_cache_cpu(int cpu)
+{
+ struct memcg_percpu_vec *mpv;
+ mpv = &per_cpu(memcg_free_vec, cpu);
+ mpv->limit = MEMCG_PCPVEC_SIZE;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void page_cgroup_stop_cache_cpu(int cpu)
+{
+ struct memcg_percpu_vec *mpv;
+ mpv = &per_cpu(memcg_free_vec, cpu);
+ mpv->limit = 0;
+}
+#endif
+
+
+/*
+ * Used when freeing memory resource controller to remove all
+ * page_cgroup (in obsolete list).
+ */
+static DEFINE_MUTEX(memcg_force_drain_mutex);
+
+static void drain_page_cgroup_local(struct work_struct *work)
+{
+ struct memcg_percpu_vec *mpv;
+ mpv = &get_cpu_var(memcg_free_vec);
+ __release_page_cgroup(mpv);
+ put_cpu_var(mpv);
+}
+
+static void drain_page_cgroup_cpu(int cpu)
+{
+ int local_cpu;
+ struct work_struct work;
+
+ local_cpu = get_cpu();
+ if (local_cpu == cpu) {
+ drain_page_cgroup_local(NULL);
+ put_cpu();
+ return;
+ }
+ put_cpu();
+
+ INIT_WORK(&work, drain_page_cgroup_local);
+ schedule_work_on(cpu, &work);
+ flush_work(&work);
+}
+
+static void drain_page_cgroup_all(void)
+{
+ mutex_lock(&memcg_force_drain_mutex);
+ schedule_on_each_cpu(drain_page_cgroup_local);
+ mutex_unlock(&memcg_force_drain_mutex);
+}
+
+
/*
* Charge the memory controller for page usage.
* Return
@@ -715,7 +830,6 @@ __mem_cgroup_uncharge_common(struct page
struct mem_cgroup *mem;
struct mem_cgroup_per_zone *mz;
unsigned long pfn = page_to_pfn(page);
- unsigned long flags;

if (!under_mem_cgroup(page))
return;
@@ -727,17 +841,12 @@ __mem_cgroup_uncharge_common(struct page
lock_page_cgroup(pc);
__ClearPageCgroupUsed(pc);
unlock_page_cgroup(pc);
+ preempt_enable();

mem = pc->mem_cgroup;
mz = page_cgroup_zoneinfo(pc);

- spin_lock_irqsave(&mz->lru_lock, flags);
- __mem_cgroup_remove_list(mz, pc);
- spin_unlock_irqrestore(&mz->lru_lock, flags);
- put_page(pc->page);
- pc->mem_cgroup = NULL;
- css_put(&mem->css);
- preempt_enable();
+ release_page_cgroup(mz, pc);
res_counter_uncharge(&mem->res, PAGE_SIZE);

return;
@@ -938,6 +1047,7 @@ static int mem_cgroup_force_empty(struct
* So, we have to do loop here until all lists are empty.
*/
while (mem->res.usage > 0) {
+ drain_page_cgroup_all();
if (atomic_read(&mem->css.cgroup->count) > 0)
goto out;
for_each_node_state(node, N_POSSIBLE)
@@ -950,6 +1060,7 @@ static int mem_cgroup_force_empty(struct
}
}
ret = 0;
+ drain_page_cgroup_all();
out:
css_put(&mem->css);
return ret;
@@ -1154,6 +1265,38 @@ static void mem_cgroup_free(struct mem_c
vfree(mem);
}

+static void mem_cgroup_init_pcp(int cpu)
+{
+ page_cgroup_start_cache_cpu(cpu);
+}
+
+static int cpu_memcgroup_callback(struct notifier_block *nb,
+ unsigned long action, void *hcpu)
+{
+ int cpu = (long)hcpu;
+
+ switch(action) {
+ case CPU_UP_PREPARE:
+ case CPU_UP_PREPARE_FROZEN:
+ mem_cgroup_init_pcp(cpu);
+ break;
+#ifdef CONFIG_HOTPLUG_CPU
+ case CPU_DOWN_PREPARE:
+ case CPU_DOWN_PREPARE_FROZEN:
+ page_cgroup_stop_cache_cpu(cpu);
+ drain_page_cgroup_cpu(cpu);
+ break;
+#endif
+ default:
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block __refdata memcgroup_nb =
+{
+ .notifier_call = cpu_memcgroup_callback,
+};

static struct cgroup_subsys_state *
mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
@@ -1164,6 +1307,10 @@ mem_cgroup_create(struct cgroup_subsys *
if (unlikely((cont->parent) == NULL)) {
page_cgroup_init();
mem = &init_mem_cgroup;
+ cpu_memcgroup_callback(&memcgroup_nb,
+ (unsigned long)CPU_UP_PREPARE,
+ (void *)(long)smp_processor_id());
+ register_hotcpu_notifier(&memcgroup_nb);
} else {
mem = mem_cgroup_alloc();
if (!mem)


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