Re: [PATCH] memcg: support ksm merge any mode per cgroup

这个地方要不要新加一个逻辑： 考虑后续新pid加入到cgroup里面情况；

我们memcg->ksm接口只是做使能； 1） 当前实现，遍历已有的使能ksm 2） 新加入pid，需要查看遍历使能ksm

On 2023/12/14 21:38, Nanyong Sun wrote:

hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8OIQR

---

Add control file "memory.ksm" to enable ksm per cgroup. Echo to 1 will set all tasks currently in the cgroup to ksm merge any mode, which means ksm gets enabled for all vma's of a process. Meanwhile echo to 0 will disable ksm for them and unmerge the merged pages. Cat the file will show the above state and ksm related profits of this cgroup.

Signed-off-by: Nanyong Sun sunnanyong@huawei.com

.../admin-guide/cgroup-v1/memory.rst | 1 + mm/memcontrol.c | 110 +++++++++++++++++- 2 files changed, 109 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst index ff456871bf4b..3fdb48435e8e 100644 --- a/Documentation/admin-guide/cgroup-v1/memory.rst +++ b/Documentation/admin-guide/cgroup-v1/memory.rst @@ -109,6 +109,7 @@ Brief summary of control files. memory.kmem.tcp.failcnt show the number of tcp buf memory usage hits limits memory.kmem.tcp.max_usage_in_bytes show max tcp buf memory usage recorded

• memory.ksm set/show ksm merge any mode ==================================== ==========================================

  1. History

diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 8a881ab21f6c..be37c2dda785 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -73,6 +73,7 @@ #include <linux/uaccess.h>

#include <trace/events/vmscan.h> +#include <linux/ksm.h>

struct cgroup_subsys memory_cgrp_subsys __read_mostly; EXPORT_SYMBOL(memory_cgrp_subsys); @@ -230,10 +231,15 @@ enum res_type { iter != NULL; \ iter = mem_cgroup_iter(NULL, iter, NULL))

+static inline bool __task_is_dying(struct task_struct *task) +{

• return tsk_is_oom_victim(task) || fatal_signal_pending(task) ||

• (task->flags & PF_EXITING);
  

+}

• static inline bool task_is_dying(void) {

• return tsk_is_oom_victim(current) || fatal_signal_pending(current) ||

• (current->flags & PF_EXITING);
  

• return __task_is_dying(current); }

  /* Some nice accessors for the vmpressure. */

@@ -5010,6 +5016,98 @@ static int mem_cgroup_slab_show(struct seq_file *m, void *p) } #endif

+#ifdef CONFIG_KSM +static int memcg_set_ksm_for_tasks(struct mem_cgroup *memcg, bool enable) +{

• struct task_struct *task;
• struct mm_struct *mm;
• struct css_task_iter it;
• int ret = 0;
• css_task_iter_start(&memcg->css, CSS_TASK_ITER_PROCS, &it);
• while (!ret && (task = css_task_iter_next(&it))) {

• if (__task_is_dying(task))
  

• 	continue;
  

• mm = get_task_mm(task);
  

• if (!mm)
  

• 	continue;
  

• if (mmap_write_lock_killable(mm)) {
  

• 	mmput(mm);
  

• 	continue;
  

• }
  

• if (enable)
  

• 	ret = ksm_enable_merge_any(mm);
  

• else
  

• 	ret = ksm_disable_merge_any(mm);
  

• mmap_write_unlock(mm);
  

• mmput(mm);
  

• }
• css_task_iter_end(&it);
• return ret;

+}

+static int memory_ksm_show(struct seq_file *m, void *v) +{

• unsigned long ksm_merging_pages = 0;
• unsigned long ksm_rmap_items = 0;
• long ksm_process_profits = 0;
• unsigned int tasks = 0;
• struct task_struct *task;
• struct mm_struct *mm;
• struct css_task_iter it;
• struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
• css_task_iter_start(&memcg->css, CSS_TASK_ITER_PROCS, &it);
• while ((task = css_task_iter_next(&it))) {

• mm = get_task_mm(task);
  

• if (!mm)
  

• 	continue;
  

• if (test_bit(MMF_VM_MERGE_ANY, &mm->flags))
  

• 	tasks++;
  

• ksm_rmap_items += mm->ksm_rmap_items;
  

• ksm_merging_pages += mm->ksm_merging_pages;
  

• ksm_process_profits += ksm_process_profit(mm);
  

• mmput(mm);
  

• }
• css_task_iter_end(&it);
• seq_printf(m, "merge any tasks: %u\n", tasks);
• seq_printf(m, "ksm_rmap_items %lu\n", ksm_rmap_items);
• seq_printf(m, "ksm_merging_pages %lu\n", ksm_merging_pages);
• seq_printf(m, "ksm_process_profits %ld\n", ksm_process_profits);
• return 0;

+}

+static ssize_t memory_ksm_write(struct kernfs_open_file *of, char *buf,

• 			size_t nbytes, loff_t off)
  

+{

• bool enable;
• int err;
• struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
• buf = strstrip(buf);
• if (!buf)

• return -EINVAL;
  

• err = kstrtobool(buf, &enable);
• if (err)

• return err;
  

• err = memcg_set_ksm_for_tasks(memcg, enable);
• if (err)

• return err;
  

• return nbytes;

+} +#endif /* CONFIG_KSM */

• static int memory_stat_show(struct seq_file *m, void *v);

  static struct cftype mem_cgroup_legacy_files[] = {

@@ -5138,6 +5236,14 @@ static struct cftype mem_cgroup_legacy_files[] = { .write = mem_cgroup_reset, .read_u64 = mem_cgroup_read_u64, }, +#ifdef CONFIG_KSM

• {

• .name = "ksm",
  

• .flags = CFTYPE_NOT_ON_ROOT,
  

• .write = memory_ksm_write,
  

• .seq_show = memory_ksm_show,
  

• },

+#endif { }, /* terminate */ };