linux/tools/cgroup/memcg_slabinfo.py
Roman Gushchin 221944736f tools/cgroup/slabinfo: update to work with struct slab
After the introduction of the dedicated struct slab to describe slab
pages by commit d122019bf0 ("mm: Split slab into its own type") and
the following removal of the corresponding struct page's fields by
commit 07f910f9b7 ("mm: Remove slab from struct page") the
memcg_slabinfo tool broke. An attempt to run it produces a trace like
this:
Traceback (most recent call last):
  File "/usr/bin/drgn", line 33, in <module>
    sys.exit(load_entry_point('drgn==0.0.16', 'console_scripts', 'drgn')())
  File "/usr/lib64/python3.9/site-packages/drgn/internal/cli.py", line 133, in main
    runpy.run_path(args.script[0], init_globals=init_globals, run_name="__main__")
  File "/usr/lib64/python3.9/runpy.py", line 268, in run_path
    return _run_module_code(code, init_globals, run_name,
  File "/usr/lib64/python3.9/runpy.py", line 97, in _run_module_code
    _run_code(code, mod_globals, init_globals,
  File "/usr/lib64/python3.9/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "memcg_slabinfo.py", line 226, in <module>
    main()
  File "memcg_slabinfo.py", line 199, in main
    cache = page.slab_cache
AttributeError: 'struct page' has no member 'slab_cache'

The problem can be fixed by explicitly casting struct page * to struct
slab * for slab pages. The tools works as expected with this fix, e.g.:

cred_jar             776    776    192   21    1 : tunables    0    0    0 : slabdata    547    547      0
kmalloc-cg-32          6      6     32  128    1 : tunables    0    0    0 : slabdata      9      9      0
files_cache            3      3    832   39    8 : tunables    0    0    0 : slabdata      8      8      0
kmalloc-cg-512         1      1    512   32    4 : tunables    0    0    0 : slabdata     10     10      0
task_struct           10     10   6720    4    8 : tunables    0    0    0 : slabdata     63     63      0
mm_struct              3      3   1664   19    8 : tunables    0    0    0 : slabdata      9      9      0
kmalloc-cg-16          1      1     16  256    1 : tunables    0    0    0 : slabdata      8      8      0
pde_opener             1      1     40  102    1 : tunables    0    0    0 : slabdata      8      8      0
anon_vma_chain       375    375     64   64    1 : tunables    0    0    0 : slabdata     81     81      0
radix_tree_node        3      3    584   28    4 : tunables    0    0    0 : slabdata    419    419      0
dentry                98     98    312   26    2 : tunables    0    0    0 : slabdata   1420   1420      0
btrfs_inode            3      3   2368   13    8 : tunables    0    0    0 : slabdata    730    730      0
signal_cache           3      3   1600   20    8 : tunables    0    0    0 : slabdata     17     17      0
sighand_cache          3      3   2240   14    8 : tunables    0    0    0 : slabdata     20     20      0
filp                  90     90    512   32    4 : tunables    0    0    0 : slabdata     95     95      0
anon_vma             214    214    200   20    1 : tunables    0    0    0 : slabdata    162    162      0
kmalloc-cg-1k          1      1   1024   32    8 : tunables    0    0    0 : slabdata     22     22      0
pid                   10     10    256   32    2 : tunables    0    0    0 : slabdata     14     14      0
kmalloc-cg-64          2      2     64   64    1 : tunables    0    0    0 : slabdata      8      8      0
kmalloc-cg-96          3      3     96   42    1 : tunables    0    0    0 : slabdata      8      8      0
sock_inode_cache       5      5   1408   23    8 : tunables    0    0    0 : slabdata     29     29      0
UNIX                   7      7   1920   17    8 : tunables    0    0    0 : slabdata     21     21      0
inode_cache           36     36   1152   28    8 : tunables    0    0    0 : slabdata    680    680      0
proc_inode_cache      26     26   1224   26    8 : tunables    0    0    0 : slabdata     64     64      0
kmalloc-cg-2k          2      2   2048   16    8 : tunables    0    0    0 : slabdata      9      9      0

v2: change naming and count_partial()/count_free()/for_each_slab()
    signatures to work with slabs, suggested by Matthew Wilcox

Fixes: 07f910f9b7 ("mm: Remove slab from struct page")
Reported-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Roman Gushchin <guro@fb.com>
Tested-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Link: https://lore.kernel.org/linux-patches/Yg2cKKnIboNu7j+p@carbon.DHCP.thefacebook.com/
2022-02-21 11:34:49 +01:00

227 lines
6.5 KiB
Python

#!/usr/bin/env drgn
#
# Copyright (C) 2020 Roman Gushchin <guro@fb.com>
# Copyright (C) 2020 Facebook
from os import stat
import argparse
import sys
from drgn.helpers.linux import list_for_each_entry, list_empty
from drgn.helpers.linux import for_each_page
from drgn.helpers.linux.cpumask import for_each_online_cpu
from drgn.helpers.linux.percpu import per_cpu_ptr
from drgn import container_of, FaultError, Object, cast
DESC = """
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 = {}
OO_SHIFT = 16
OO_MASK = ((1 << OO_SHIFT) - 1)
def err(s):
print('slabinfo.py: error: %s' % s, file=sys.stderr, flush=True)
sys.exit(1)
def find_memcg_ids(css=prog['root_mem_cgroup'].css, prefix=''):
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 = prefix + '/' + css.cgroup.kn.name.string_().decode('utf-8')
memcg = container_of(css, 'struct mem_cgroup', 'css')
MEMCGS[css.cgroup.kn.id.value_()] = memcg
find_memcg_ids(css, name)
def is_root_cache(s):
try:
return False if s.memcg_params.root_cache else True
except AttributeError:
return 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_objs = 0
for slab in list_for_each_entry('struct slab', n.partial.address_of_(),
'slab_list'):
nr_objs += fn(slab)
return nr_objs
def count_free(slab):
return slab.objects - slab.inuse
def slub_get_slabinfo(s, cfg):
nr_slabs = 0
nr_objs = 0
nr_free = 0
for node in range(cfg['nr_nodes']):
n = s.node[node]
nr_slabs += n.nr_slabs.counter.value_()
nr_objs += n.total_objects.counter.value_()
nr_free += 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, objs):
if cfg['allocator'] == 'SLUB':
sinfo = slub_get_slabinfo(s, cfg)
else:
err('SLAB isn\'t supported yet')
if cfg['shared_slab_pages']:
sinfo['active_objs'] = objs
sinfo['num_objs'] = objs
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 = {}
cfg['nr_nodes'] = prog['nr_online_nodes'].value_()
if prog.type('struct kmem_cache').members[1].name == 'flags':
cfg['allocator'] = 'SLUB'
elif prog.type('struct kmem_cache').members[1].name == 'batchcount':
cfg['allocator'] = 'SLAB'
else:
err('Can\'t determine the slab allocator')
cfg['shared_slab_pages'] = False
try:
if prog.type('struct obj_cgroup'):
cfg['shared_slab_pages'] = True
except:
pass
return cfg
def for_each_slab(prog):
PGSlab = 1 << prog.constant('PG_slab')
PGHead = 1 << prog.constant('PG_head')
for page in for_each_page(prog):
try:
if page.flags.value_() & PGSlab:
yield cast('struct slab *', page)
except FaultError:
pass
def main():
parser = argparse.ArgumentParser(description=DESC,
formatter_class=
argparse.RawTextHelpFormatter)
parser.add_argument('cgroup', metavar='CGROUP',
help='Target memory cgroup')
args = parser.parse_args()
try:
cgroup_id = stat(args.cgroup).st_ino
find_memcg_ids()
memcg = MEMCGS[cgroup_id]
except KeyError:
err('Can\'t find the memory cgroup')
cfg = detect_kernel_config()
print('# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>'
' : tunables <limit> <batchcount> <sharedfactor>'
' : slabdata <active_slabs> <num_slabs> <sharedavail>')
if cfg['shared_slab_pages']:
obj_cgroups = set()
stats = {}
caches = {}
# find memcg pointers belonging to the specified cgroup
obj_cgroups.add(memcg.objcg.value_())
for ptr in list_for_each_entry('struct obj_cgroup',
memcg.objcg_list.address_of_(),
'list'):
obj_cgroups.add(ptr.value_())
# look over all slab folios and look for objects belonging
# to the given memory cgroup
for slab in for_each_slab(prog):
objcg_vec_raw = slab.memcg_data.value_()
if objcg_vec_raw == 0:
continue
cache = slab.slab_cache
if not cache:
continue
addr = cache.value_()
caches[addr] = cache
# clear the lowest bit to get the true obj_cgroups
objcg_vec = Object(prog, 'struct obj_cgroup **',
value=objcg_vec_raw & ~1)
if addr not in stats:
stats[addr] = 0
for i in range(oo_objects(cache)):
if objcg_vec[i].value_() in obj_cgroups:
stats[addr] += 1
for addr in caches:
if stats[addr] > 0:
cache_show(caches[addr], cfg, stats[addr])
else:
for s in list_for_each_entry('struct kmem_cache',
memcg.kmem_caches.address_of_(),
'memcg_params.kmem_caches_node'):
cache_show(s, cfg, None)
main()