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Date: Sun, 31 Jul 2022 00:35:28 +0800
From: Xin Hao <xhao@...ux.alibaba.com>
To: adobriyan@...il.com
Cc: akpm@...ux-foundation.org, keescook@...omium.org,
xhao@...ux.alibaba.com, linux-kernel@...r.kernel.org,
linux-mm@...ck.org
Subject: [RFC PATCH] mm: add last level page table numa info to /proc/pid/numa_pgtable
In many data center servers, the shared memory architectures is
Non-Uniform Memory Access (NUMA), remote numa node data access
often brings a high latency problem, but what we are easy to ignore
is that the page table remote numa access, It can also leads to a
performance degradation.
So there add a new interface in /proc, This will help developers to
get more info about performance issues if they are caused by cross-NUMA.
Signed-off-by: Xin Hao <xhao@...ux.alibaba.com>
---
fs/proc/base.c | 6 ++-
fs/proc/internal.h | 1 +
fs/proc/task_mmu.c | 129 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 134 insertions(+), 2 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 8dfa36a99c74..de60351813ec 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2626,7 +2626,7 @@ static struct dentry *proc_pident_instantiate(struct dentry *dentry,
return d_splice_alias(inode, dentry);
}
-static struct dentry *proc_pident_lookup(struct inode *dir,
+static struct dentry *proc_pident_lookup(struct inode *dir,
struct dentry *dentry,
const struct pid_entry *p,
const struct pid_entry *end)
@@ -2839,7 +2839,7 @@ static const struct pid_entry attr_dir_stuff[] = {
static int proc_attr_dir_readdir(struct file *file, struct dir_context *ctx)
{
- return proc_pident_readdir(file, ctx,
+ return proc_pident_readdir(file, ctx,
attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
}
@@ -3224,6 +3224,7 @@ static const struct pid_entry tgid_base_stuff[] = {
REG("maps", S_IRUGO, proc_pid_maps_operations),
#ifdef CONFIG_NUMA
REG("numa_maps", S_IRUGO, proc_pid_numa_maps_operations),
+ REG("numa_pgtable", S_IRUGO, proc_pid_numa_pgtable_operations),
#endif
REG("mem", S_IRUSR|S_IWUSR, proc_mem_operations),
LNK("cwd", proc_cwd_link),
@@ -3571,6 +3572,7 @@ static const struct pid_entry tid_base_stuff[] = {
#endif
#ifdef CONFIG_NUMA
REG("numa_maps", S_IRUGO, proc_pid_numa_maps_operations),
+ REG("numa_pgtable", S_IRUGO, proc_pid_numa_pgtable_operations),
#endif
REG("mem", S_IRUSR|S_IWUSR, proc_mem_operations),
LNK("cwd", proc_cwd_link),
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 06a80f78433d..e7ed9ef097b6 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -296,6 +296,7 @@ struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode);
extern const struct file_operations proc_pid_maps_operations;
extern const struct file_operations proc_pid_numa_maps_operations;
+extern const struct file_operations proc_pid_numa_pgtable_operations;
extern const struct file_operations proc_pid_smaps_operations;
extern const struct file_operations proc_pid_smaps_rollup_operations;
extern const struct file_operations proc_clear_refs_operations;
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 2d04e3470d4c..a51befb47ea8 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1999,4 +1999,133 @@ const struct file_operations proc_pid_numa_maps_operations = {
.release = proc_map_release,
};
+struct pgtable_numa_maps {
+ unsigned long node[MAX_NUMNODES];
+};
+
+struct pgtable_numa_private {
+ struct proc_maps_private proc_maps;
+ struct pgtable_numa_maps md;
+};
+
+static void gather_pgtable_stats(struct page *page, struct pgtable_numa_maps *md)
+{
+ md->node[page_to_nid(page)] += 1;
+}
+
+static struct page *can_gather_pgtable_numa_stats(pmd_t pmd, struct vm_area_struct *vma,
+ unsigned long addr)
+{
+ struct page *page;
+ int nid;
+
+ if (!pmd_present(pmd))
+ return NULL;
+
+ if (pmd_huge(pmd))
+ return NULL;
+
+ page = pmd_page(pmd);
+ nid = page_to_nid(page);
+ if (!node_isset(nid, node_states[N_MEMORY]))
+ return NULL;
+
+ return page;
+}
+
+static int gather_pgtable_numa_stats(pmd_t *pmd, unsigned long addr,
+ unsigned long end, struct mm_walk *walk)
+{
+ struct pgtable_numa_maps *md = walk->private;
+ struct vm_area_struct *vma = walk->vma;
+ struct page *page;
+
+ if (pmd_huge(*pmd)) {
+ struct page *pmd_page;
+
+ pmd_page = virt_to_page(pmd);
+ if (!pmd_page)
+ return 0;
+
+ if (!node_isset(page_to_nid(pmd_page), node_states[N_MEMORY]))
+ return 0;
+
+ gather_pgtable_stats(pmd_page, md);
+ goto out;
+ }
+
+ page = can_gather_pgtable_numa_stats(*pmd, vma, addr);
+ if (!page)
+ return 0;
+
+ gather_pgtable_stats(page, md);
+
+out:
+ cond_resched();
+ return 0;
+}
+
+static const struct mm_walk_ops show_numa_pgtable_ops = {
+ .pmd_entry = gather_pgtable_numa_stats,
+};
+
+/*
+ * Display the page talbe allocated per node via /proc.
+ */
+static int show_numa_pgtable(struct seq_file *m, void *v)
+{
+ struct pgtable_numa_private *numa_priv = m->private;
+ struct vm_area_struct *vma = v;
+ struct pgtable_numa_maps *md = &numa_priv->md;
+ struct mm_struct *mm = vma->vm_mm;
+ struct file *file = vma->vm_file;
+ int nid;
+
+ if (!mm)
+ return 0;
+
+ memset(md, 0, sizeof(*md));
+
+ seq_printf(m, "%08lx ", vma->vm_start);
+
+ if (file) {
+ seq_puts(m, " file=");
+ seq_file_path(m, file, "\n\t= ");
+ } else if (vma->vm_start <= mm->brk && vma->vm_end >= mm->start_brk) {
+ seq_puts(m, " heap");
+ } else if (is_stack(vma)) {
+ seq_puts(m, " stack");
+ }
+
+ /* mmap_lock is held by m_start */
+ walk_page_vma(vma, &show_numa_pgtable_ops, md);
+
+ for_each_node_state(nid, N_MEMORY) {
+ if (md->node[nid])
+ seq_printf(m, " N%d=%lu", nid, md->node[nid]);
+ }
+ seq_putc(m, '\n');
+
+ return 0;
+}
+static const struct seq_operations proc_pid_numa_pgtable_op = {
+ .start = m_start,
+ .next = m_next,
+ .stop = m_stop,
+ .show = show_numa_pgtable,
+};
+
+static int pid_numa_pgtable_open(struct inode *inode, struct file *file)
+{
+ return proc_maps_open(inode, file, &proc_pid_numa_pgtable_op,
+ sizeof(struct pgtable_numa_private));
+}
+
+const struct file_operations proc_pid_numa_pgtable_operations = {
+ .open = pid_numa_pgtable_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = proc_map_release,
+};
+
#endif /* CONFIG_NUMA */
--
2.31.0
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