Re: [RFC V3 PATCH] mm: add last level page table numa info to /proc/pid/numa_pgtable
From: haoxin
Date: Mon Aug 01 2022 - 06:53:30 EST
在 2022/8/1 下午2:06, Baolin Wang 写道:
Hi Xin,
On 8/1/2022 11:27 AM, Xin Hao wrote:
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.
V2 -> V3
1, Fix compile warning bug.
V1 -> V2
1, As Matthew Wilcox advise, Simplify the code.
2, Do some codes format fix.
Please move the changes history under your 'Signed-off-by' with '---'.
V2:
https://lore.kernel.org/linux-mm/20220731155223.60238-1-xhao@xxxxxxxxxxxxxxxxx/
V1:
https://lore.kernel.org/linux-mm/YuVqdcY8Ibib2LJa@xxxxxxxxxxxxxxxxxxxx/T/
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Xin Hao <xhao@xxxxxxxxxxxxxxxxx>
---
fs/proc/base.c | 2 ++
fs/proc/internal.h | 1 +
fs/proc/task_mmu.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 90 insertions(+)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 8dfa36a99c74..487e82dd3275 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -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..77b7a49757f5 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1999,4 +1999,91 @@ const struct file_operations
proc_pid_numa_maps_operations = {
.release = proc_map_release,
};
+struct pgtable_numa_private {
+ struct proc_maps_private proc_maps;
+ unsigned long node[MAX_NUMNODES];
+};
+
+static int gather_pgtable_numa_stats(pmd_t *pmd, unsigned long addr,
+ unsigned long end, struct mm_walk *walk)
+{
+ struct pgtable_numa_private *priv = walk->private;
+ struct page *page;
+ int nid;
+
+ if (pmd_huge(*pmd)) {
+ page = virt_to_page(pmd);
+ } else {
+ page = pmd_page(*pmd);
You should validate if the pmd is valid or present before getting the
pagetable page.
if (pmd_none(*pmd) || !pmd_present(*pmd))
Another issue is I think you should hold the pmd lock to call
pmd_page(), since after the validation of pmd_huge(), the pmd entry
can be modified by other threads if you did not hold the pmd lock.
Thanks, Baolin, i will fix it in the next version.
+ }
+
+ nid = page_to_nid(page);
+ priv->node[nid]++;
+
+ 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 mm_struct *mm = vma->vm_mm;
+ struct file *file = vma->vm_file;
+ int nid;
+
+ if (!mm)
+ return 0;
+
+ memset(numa_priv->node, 0, sizeof(numa_priv->node));
+
+ 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, numa_priv);
+
+ for_each_node_state(nid, N_MEMORY) {
+ if (numa_priv->node[nid])
+ seq_printf(m, " N%d=%lu", nid, numa_priv->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