[PATCH] /proc/<pid>/numa_maps to show on which nodes pages reside

This patch was recently discussed on linux-mm:
http://marc.theaimsgroup.com/?t=112085728500002&r=1&w=2

I inherited a large code base from Ray for page migration.  There was a
small patch in there that I find to be very useful since it allows the
display of the locality of the pages in use by a process.  I reworked that
patch and came up with a /proc/<pid>/numa_maps that gives more information
about the vma's of a process.  numa_maps is indexes by the start address
found in /proc/<pid>/maps.  F.e.  with this patch you can see the page use
of the "getty" process:

margin:/proc/12008 # cat maps
00000000-00004000 r--p 00000000 00:00 0
2000000000000000-200000000002c000 r-xp 00000000 08:04 516                /lib/ld-2.3.3.so
2000000000038000-2000000000040000 rw-p 00028000 08:04 516                /lib/ld-2.3.3.so
2000000000040000-2000000000044000 rw-p 2000000000040000 00:00 0
2000000000058000-2000000000260000 r-xp 00000000 08:04 54707842           /lib/tls/libc.so.6.1
2000000000260000-2000000000268000 ---p 00208000 08:04 54707842           /lib/tls/libc.so.6.1
2000000000268000-2000000000274000 rw-p 00200000 08:04 54707842           /lib/tls/libc.so.6.1
2000000000274000-2000000000280000 rw-p 2000000000274000 00:00 0
2000000000280000-20000000002b4000 r--p 00000000 08:04 9126923            /usr/lib/locale/en_US.utf8/LC_CTYPE
2000000000300000-2000000000308000 r--s 00000000 08:04 60071467           /usr/lib/gconv/gconv-modules.cache
2000000000318000-2000000000328000 rw-p 2000000000318000 00:00 0
4000000000000000-4000000000008000 r-xp 00000000 08:04 29576399           /sbin/mingetty
6000000000004000-6000000000008000 rw-p 00004000 08:04 29576399           /sbin/mingetty
6000000000008000-600000000002c000 rw-p 6000000000008000 00:00 0          [heap]
60000fff7fffc000-60000fff80000000 rw-p 60000fff7fffc000 00:00 0
60000ffffff44000-60000ffffff98000 rw-p 60000ffffff44000 00:00 0          [stack]
a000000000000000-a000000000020000 ---p 00000000 00:00 0                  [vdso]

cat numa_maps
2000000000000000 default MaxRef=43 Pages=11 Mapped=11 N0=4 N1=3 N2=2 N3=2
2000000000038000 default MaxRef=1 Pages=2 Mapped=2 Anon=2 N0=2
2000000000040000 default MaxRef=1 Pages=1 Mapped=1 Anon=1 N0=1
2000000000058000 default MaxRef=43 Pages=61 Mapped=61 N0=14 N1=15 N2=16 N3=16
2000000000268000 default MaxRef=1 Pages=2 Mapped=2 Anon=2 N0=2
2000000000274000 default MaxRef=1 Pages=3 Mapped=3 Anon=3 N0=3
2000000000280000 default MaxRef=8 Pages=3 Mapped=3 N0=3
2000000000300000 default MaxRef=8 Pages=2 Mapped=2 N0=2
2000000000318000 default MaxRef=1 Pages=1 Mapped=1 Anon=1 N2=1
4000000000000000 default MaxRef=6 Pages=2 Mapped=2 N1=2
6000000000004000 default MaxRef=1 Pages=1 Mapped=1 Anon=1 N0=1
6000000000008000 default MaxRef=1 Pages=1 Mapped=1 Anon=1 N0=1
60000fff7fffc000 default MaxRef=1 Pages=1 Mapped=1 Anon=1 N0=1
60000ffffff44000 default MaxRef=1 Pages=1 Mapped=1 Anon=1 N0=1

getty uses ld.so.  The first vma is the code segment which is used by 43
other processes and the pages are evenly distributed over the 4 nodes.

The second vma is the process specific data portion for ld.so.  This is
only one page.

The display format is:

<startaddress>	 Links to information in /proc/<pid>/map
<memory policy>  This can be "default" "interleave={}", "prefer=<node>" or "bind={<zones>}"
MaxRef=		<maximum reference to a page in this vma>
Pages=		<Nr of pages in use>
Mapped=		<Nr of pages with mapcount >
Anon=		<nr of anonymous pages>
Nx=		<Nr of pages on Node x>

The content of the proc-file is self-evident.  If this would be tied into
the sparsemem system then the contents of this file would not be too
useful.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 132 insertions, 0 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 28b4a0253a92..64e84cadfa3c 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -2,6 +2,8 @@
 #include <linux/hugetlb.h>
 #include <linux/mount.h>
 #include <linux/seq_file.h>
+#include <linux/pagemap.h>
+#include <linux/mempolicy.h>
 #include <asm/elf.h>
 #include <asm/uaccess.h>
 #include "internal.h"
@@ -233,3 +235,133 @@ struct seq_operations proc_pid_maps_op = {
         .stop   = m_stop,
         .show   = show_map
 };
+
+#ifdef CONFIG_NUMA
+
+struct numa_maps {
+        unsigned long pages;
+        unsigned long anon;
+        unsigned long mapped;
+        unsigned long mapcount_max;
+        unsigned long node[MAX_NUMNODES];
+};
+
+/*
+ * Calculate numa node maps for a vma
+ */
+static struct numa_maps *get_numa_maps(const struct vm_area_struct *vma)
+{
+        struct page *page;
+        unsigned long vaddr;
+        struct mm_struct *mm = vma->vm_mm;
+        int i;
+        struct numa_maps *md = kmalloc(sizeof(struct numa_maps), GFP_KERNEL);
+
+        if (!md)
+                return NULL;
+        md->pages = 0;
+        md->anon = 0;
+        md->mapped = 0;
+        md->mapcount_max = 0;
+        for_each_node(i)
+                md->node[i] =0;
+
+        spin_lock(&mm->page_table_lock);
+        for (vaddr = vma->vm_start; vaddr < vma->vm_end; vaddr += PAGE_SIZE) {
+                page = follow_page(mm, vaddr, 0);
+                if (page) {
+                        int count = page_mapcount(page);
+
+                        if (count)
+                                md->mapped++;
+                        if (count > md->mapcount_max)
+                                md->mapcount_max = count;
+                        md->pages++;
+                        if (PageAnon(page))
+                                md->anon++;
+                        md->node[page_to_nid(page)]++;
+                }
+        }
+        spin_unlock(&mm->page_table_lock);
+        return md;
+}
+
+static int show_numa_map(struct seq_file *m, void *v)
+{
+        struct task_struct *task = m->private;
+        struct vm_area_struct *vma = v;
+        struct mempolicy *pol;
+        struct numa_maps *md;
+        struct zone **z;
+        int n;
+        int first;
+
+        if (!vma->vm_mm)
+                return 0;
+
+        md = get_numa_maps(vma);
+        if (!md)
+                return 0;
+
+        seq_printf(m, "%08lx", vma->vm_start);
+        pol = get_vma_policy(task, vma, vma->vm_start);
+        /* Print policy */
+        switch (pol->policy) {
+        case MPOL_PREFERRED:
+                seq_printf(m, " prefer=%d", pol->v.preferred_node);
+                break;
+        case MPOL_BIND:
+                seq_printf(m, " bind={");
+                first = 1;
+                for (z = pol->v.zonelist->zones; *z; z++) {
+
+                        if (!first)
+                                seq_putc(m, ',');
+                        else
+                                first = 0;
+                        seq_printf(m, "%d/%s", (*z)->zone_pgdat->node_id,
+                                        (*z)->name);
+                }
+                seq_putc(m, '}');
+                break;
+        case MPOL_INTERLEAVE:
+                seq_printf(m, " interleave={");
+                first = 1;
+                for_each_node(n) {
+                        if (test_bit(n, pol->v.nodes)) {
+                                if (!first)
+                                        seq_putc(m,',');
+                                else
+                                        first = 0;
+                                seq_printf(m, "%d",n);
+                        }
+                }
+                seq_putc(m, '}');
+                break;
+        default:
+                seq_printf(m," default");
+                break;
+        }
+        seq_printf(m, " MaxRef=%lu Pages=%lu Mapped=%lu",
+                        md->mapcount_max, md->pages, md->mapped);
+        if (md->anon)
+                seq_printf(m," Anon=%lu",md->anon);
+
+        for_each_online_node(n) {
+                if (md->node[n])
+                        seq_printf(m, " N%d=%lu", n, md->node[n]);
+        }
+        seq_putc(m, '\n');
+        kfree(md);
+        if (m->count < m->size)  /* vma is copied successfully */
+                m->version = (vma != get_gate_vma(task)) ? vma->vm_start : 0;
+        return 0;
+}
+
+struct seq_operations proc_pid_numa_maps_op = {
+        .start  = m_start,
+        .next   = m_next,
+        .stop   = m_stop,
+        .show   = show_numa_map
+};
+#endif