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ksm: count ksm merging pages for each process 

Some applications or containers want to use KSM by calling madvise() to
advise areas of address space to be MERGEABLE.  But they may not know
which applications are more likely to cause real merges in the
deployment.  If this patch is applied, it helps them know their
corresponding number of merged pages, and then optimize their app code.

As current KSM only counts the number of KSM merging pages(e.g. 
ksm_pages_sharing and ksm_pages_shared) of the whole system, we cannot see
the more fine-grained KSM merging, for the upper application optimization,
the merging area cannot be set easily according to the KSM page merging
probability of each process.  Therefore, it is necessary to add extra
statistical means so that the upper level users can know the detailed KSM
merging information of each process.

We add a new proc file named as ksm_merging_pages under /proc/<pid>/ to
indicate the involved ksm merging pages of this process.

[akpm@linux-foundation.org: fix comment typo, remove BUG_ON()s]
Link: https://lkml.kernel.org/r/20220325082318.2352853-1-xu.xin16@zte.com.cn
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Yang Yang <yang.yang29@zte.com.cn>
Reviewed-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Reported-by: Zeal Robot <zealci@zte.com.cn>
Cc: Kees Cook <keescook@chromium.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Ohhoon Kwon <ohoono.kwon@samsung.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Stephen Brennan <stephen.s.brennan@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Feng Tang <feng.tang@intel.com>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Cc: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
xu xin 2022-04-28 23:16:16 -07:00 committed by akpm
parent ba91fb7dd0
commit 7609385337
3 changed files with 37 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
fs/proc/base.c
View File

@ -3154,6 +3154,22 @@ static int proc_pid_patch_state(struct seq_file *m, struct pid_namespace *ns,
}
#endif /* CONFIG_LIVEPATCH */
#ifdef CONFIG_KSM
static int proc_pid_ksm_merging_pages(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *task)
{
struct mm_struct *mm;
mm = get_task_mm(task);
if (mm) {
seq_printf(m, "%lu\n", mm->ksm_merging_pages);
mmput(mm);
}
return 0;
}
#endif /* CONFIG_KSM */
#ifdef CONFIG_STACKLEAK_METRICS
static int proc_stack_depth(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *task)
@ -3285,6 +3301,9 @@ static const struct pid_entry tgid_base_stuff[] = {
#ifdef CONFIG_SECCOMP_CACHE_DEBUG
ONE("seccomp_cache", S_IRUSR, proc_pid_seccomp_cache),
#endif
#ifdef CONFIG_KSM
ONE("ksm_merging_pages", S_IRUSR, proc_pid_ksm_merging_pages),
#endif
};
static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)
@ -3618,6 +3637,9 @@ static const struct pid_entry tid_base_stuff[] = {
#ifdef CONFIG_SECCOMP_CACHE_DEBUG
ONE("seccomp_cache", S_IRUSR, proc_pid_seccomp_cache),
#endif
#ifdef CONFIG_KSM
ONE("ksm_merging_pages", S_IRUSR, proc_pid_ksm_merging_pages),
#endif
};
static int proc_tid_base_readdir(struct file *file, struct dir_context *ctx)

7
include/linux/mm_types.h
View File

@ -654,6 +654,13 @@ struct mm_struct {
#ifdef CONFIG_IOMMU_SVA
u32 pasid;
#endif
#ifdef CONFIG_KSM
/*
* Represent how many pages of this process are involved in KSM
* merging.
*/
unsigned long ksm_merging_pages;
#endif
} __randomize_layout;

8
mm/ksm.c
View File

@ -638,6 +638,9 @@ static void remove_node_from_stable_tree(struct stable_node *stable_node)
ksm_pages_sharing--;
else
ksm_pages_shared--;
rmap_item->mm->ksm_merging_pages--;
VM_BUG_ON(stable_node->rmap_hlist_len <= 0);
stable_node->rmap_hlist_len--;
put_anon_vma(rmap_item->anon_vma);
@ -785,6 +788,9 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
ksm_pages_sharing--;
else
ksm_pages_shared--;
rmap_item->mm->ksm_merging_pages--;
VM_BUG_ON(stable_node->rmap_hlist_len <= 0);
stable_node->rmap_hlist_len--;
@ -2007,6 +2013,8 @@ static void stable_tree_append(struct rmap_item *rmap_item,
ksm_pages_sharing++;
else
ksm_pages_shared++;
rmap_item->mm->ksm_merging_pages++;
}
/*