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#!/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()
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