[PATCH v2 26/28] tools/cgroup: add slabinfo.py tool

[Roman Gushchin]

Add a drgn-based tool to display slab information for a given memcg.
Can replace cgroup v1 memory.kmem.slabinfo interface on cgroup v2,
but in a more flexiable way.

Currently supports only SLUB configuration, but SLAB can be trivially
added later.

Output example:
$ sudo ./tools/cgroup/slabinfo.py /sys/fs/cgroup/user.slice/user-111017.sli=
ce/user\@111017.service
shmem_inode_cache     92     92    704   46    8 : tunables    0    0    0 =
: slabdata      2      2      0
eventpoll_pwq         56     56     72   56    1 : tunables    0    0    0 =
: slabdata      1      1      0
eventpoll_epi         32     32    128   32    1 : tunables    0    0    0 =
: slabdata      1      1      0
kmalloc-8              0      0      8  512    1 : tunables    0    0    0 =
: slabdata      0      0      0
kmalloc-96             0      0     96   42    1 : tunables    0    0    0 =
: slabdata      0      0      0
kmalloc-2048           0      0   2048   16    8 : tunables    0    0    0 =
: slabdata      0      0      0
kmalloc-64           128    128     64   64    1 : tunables    0    0    0 =
: slabdata      2      2      0
mm_struct            160    160   1024   32    8 : tunables    0    0    0 =
: slabdata      5      5      0
signal_cache          96     96   1024   32    8 : tunables    0    0    0 =
: slabdata      3      3      0
sighand_cache         45     45   2112   15    8 : tunables    0    0    0 =
: slabdata      3      3      0
files_cache          138    138    704   46    8 : tunables    0    0    0 =
: slabdata      3      3      0
task_delay_info      153    153     80   51    1 : tunables    0    0    0 =
: slabdata      3      3      0
task_struct           27     27   3520    9    8 : tunables    0    0    0 =
: slabdata      3      3      0
radix_tree_node       56     56    584   28    4 : tunables    0    0    0 =
: slabdata      2      2      0
btrfs_inode          140    140   1136   28    8 : tunables    0    0    0 =
: slabdata      5      5      0
kmalloc-1024          64     64   1024   32    8 : tunables    0    0    0 =
: slabdata      2      2      0
kmalloc-192           84     84    192   42    2 : tunables    0    0    0 =
: slabdata      2      2      0
inode_cache           54     54    600   27    4 : tunables    0    0    0 =
: slabdata      2      2      0
kmalloc-128            0      0    128   32    1 : tunables    0    0    0 =
: slabdata      0      0      0
kmalloc-512           32     32    512   32    4 : tunables    0    0    0 =
: slabdata      1      1      0
skbuff_head_cache     32     32    256   32    2 : tunables    0    0    0 =
: slabdata      1      1      0
sock_inode_cache      46     46    704   46    8 : tunables    0    0    0 =
: slabdata      1      1      0
cred_jar             378    378    192   42    2 : tunables    0    0    0 =
: slabdata      9      9      0
proc_inode_cache      96     96    672   24    4 : tunables    0    0    0 =
: slabdata      4      4      0
dentry               336    336    192   42    2 : tunables    0    0    0 =
: slabdata      8      8      0
filp                 697    864    256   32    2 : tunables    0    0    0 =
: slabdata     27     27      0
anon_vma             644    644     88   46    1 : tunables    0    0    0 =
: slabdata     14     14      0
pid                 1408   1408     64   64    1 : tunables    0    0    0 =
: slabdata     22     22      0
vm_area_struct      1200   1200    200   40    2 : tunables    0    0    0 =
: slabdata     30     30      0

Signed-off-by: Roman Gushchin <guro@xxxxxx>
Cc: Waiman Long <longman@xxxxxxxxxx>
Cc: Tobin C. Harding <tobin@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
---
 tools/cgroup/slabinfo.py | 158 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 158 insertions(+)
 create mode 100755 tools/cgroup/slabinfo.py

diff --git a/tools/cgroup/slabinfo.py b/tools/cgroup/slabinfo.py
new file mode 100755
index 000000000000..0dc3a1fc260c
--- /dev/null
+++ b/tools/cgroup/slabinfo.py
@@ -0,0 +1,158 @@
+#!/usr/bin/env drgn
+#
+# Copyright (C) 2019 Roman Gushchin <guro@xxxxxx>
+# Copyright (C) 2019 Facebook
+
+from os import stat
+import argparse
+import sys
+
+from drgn.helpers.linux import list_for_each_entry, list_empty
+from drgn import container_of
+
+
+DESC =3D """
+This is a drgn script to provide slab statistics for memory cgroups.
+It supports cgroup v2 and v1 and can emulate memory.kmem.slabinfo
+interface of cgroup v1.
+For drgn, visit https://github.com/osandov/drgn.
+"""
+
+
+MEMCGS =3D {}
+
+OO_SHIFT =3D 16
+OO_MASK =3D ((1 << OO_SHIFT) - 1)
+
+
+def err(s):
+    print('slabinfo.py: error: %s' % s, file=3Dsys.stderr, flush=3DTrue)
+    sys.exit(1)
+
+
+def find_memcg_ids(css=3Dprog['root_mem_cgroup'].css, prefix=3D''):
+    if not list_empty(css.children.address_of_()):
+        for css in list_for_each_entry('struct cgroup_subsys_state',
+                                       css.children.address_of_(),
+                                       'sibling'):
+            name =3D prefix + '/' + css.cgroup.kn.name.string_().decode('u=
tf-8')
+            memcg =3D container_of(css, 'struct mem_cgroup', 'css')
+            MEMCGS[css.cgroup.kn.id.value_()] =3D memcg
+            find_memcg_ids(css, name)
+
+
+def is_root_cache(s):
+    return False if s.memcg_params.root_cache else True
+
+
+def cache_name(s):
+    if is_root_cache(s):
+        return s.name.string_().decode('utf-8')
+    else:
+        return s.memcg_params.root_cache.name.string_().decode('utf-8')
+
+
+# SLUB
+
+def oo_order(s):
+    return s.oo.x >> OO_SHIFT
+
+
+def oo_objects(s):
+    return s.oo.x & OO_MASK
+
+
+def count_partial(n, fn):
+    nr_pages =3D 0
+    for page in list_for_each_entry('struct page', n.partial.address_of_()=
,
+                                    'lru'):
+         nr_pages +=3D fn(page)
+    return nr_pages
+
+
+def count_free(page):
+    return page.objects - page.inuse
+
+
+def slub_get_slabinfo(s, cfg):
+    nr_slabs =3D 0
+    nr_objs =3D 0
+    nr_free =3D 0
+
+    for node in range(cfg['nr_nodes']):
+        n =3D s.node[node]
+        nr_slabs +=3D n.nr_slabs.counter.value_()
+        nr_objs +=3D n.total_objects.counter.value_()
+        nr_free +=3D count_partial(n, count_free)
+
+    return {'active_objs': nr_objs - nr_free,
+            'num_objs': nr_objs,
+            'active_slabs': nr_slabs,
+            'num_slabs': nr_slabs,
+            'objects_per_slab': oo_objects(s),
+            'cache_order': oo_order(s),
+            'limit': 0,
+            'batchcount': 0,
+            'shared': 0,
+            'shared_avail': 0}
+
+
+def cache_show(s, cfg):
+    if cfg['allocator'] =3D=3D 'SLUB':
+        sinfo =3D slub_get_slabinfo(s, cfg)
+    else:
+        err('SLAB isn\'t supported yet')
+
+    print('%-17s %6lu %6lu %6u %4u %4d'
+          ' : tunables %4u %4u %4u'
+          ' : slabdata %6lu %6lu %6lu' % (
+              cache_name(s), sinfo['active_objs'], sinfo['num_objs'],
+              s.size, sinfo['objects_per_slab'], 1 << sinfo['cache_order']=
,
+              sinfo['limit'], sinfo['batchcount'], sinfo['shared'],
+              sinfo['active_slabs'], sinfo['num_slabs'],
+              sinfo['shared_avail']))
+
+
+def detect_kernel_config():
+    cfg =3D {}
+
+    cfg['nr_nodes'] =3D prog['nr_online_nodes'].value_()
+
+    if prog.type('struct kmem_cache').members[1][1] =3D=3D 'flags':
+        cfg['allocator'] =3D 'SLUB'
+    elif prog.type('struct kmem_cache').members[1][1] =3D=3D 'batchcount':
+        cfg['allocator'] =3D 'SLAB'
+    else:
+        err('Can\'t determine the slab allocator')
+
+    return cfg
+
+
+def main():
+    parser =3D argparse.ArgumentParser(description=3DDESC,
+                                     formatter_class=3D
+                                     argparse.RawTextHelpFormatter)
+    parser.add_argument('cgroup', metavar=3D'CGROUP',
+                        help=3D'Target memory cgroup')
+    args =3D parser.parse_args()
+
+    try:
+        cgroup_id =3D stat(args.cgroup).st_ino
+        find_memcg_ids()
+        memcg =3D MEMCGS[cgroup_id]
+    except KeyError:
+        err('Can\'t find the memory cgroup')
+
+    cfg =3D detect_kernel_config()
+
+    print('# name            <active_objs> <num_objs> <objsize> <objpersla=
b> <pagesperslab>'
+          ' : tunables <limit> <batchcount> <sharedfactor>'
+          ' : slabdata <active_slabs> <num_slabs> <sharedavail>')
+
+    for s in list_for_each_entry('struct kmem_cache',
+                                 memcg.kmem_caches.address_of_(),
+                                 'memcg_params.kmem_caches_node'):
+        cache_show(s, cfg)
+
+
+main()
--=20
2.24.1