tools/cgroup/memcg_slabinfo.py

   1 #!/usr/bin/env drgn
   2 #
   3 # Copyright (C) 2020 Roman Gushchin <guro@fb.com>
   4 # Copyright (C) 2020 Facebook
   5
   6 from os import stat
   7 import argparse
   8 import sys
   9
  10 from drgn.helpers.linux import list_for_each_entry, list_empty
  11 from drgn.helpers.linux import for_each_page
  12 from drgn.helpers.linux.cpumask import for_each_online_cpu
  13 from drgn.helpers.linux.percpu import per_cpu_ptr
  14 from drgn import container_of, FaultError, Object, cast
  15
  16
  17 DESC = """
  18 This is a drgn script to provide slab statistics for memory cgroups.
  19 It supports cgroup v2 and v1 and can emulate memory.kmem.slabinfo
  20 interface of cgroup v1.
  21 For drgn, visit https://github.com/osandov/drgn.
  22 """
  23
  24
  25 MEMCGS = {}
  26
  27 OO_SHIFT = 16
  28 OO_MASK = ((1 << OO_SHIFT) - 1)
  29
  30
  31 def err(s):
  32     print('slabinfo.py: error: %s' % s, file=sys.stderr, flush=True)
  33     sys.exit(1)
  34
  35
  36 def find_memcg_ids(css=prog['root_mem_cgroup'].css, prefix=''):
  37     if not list_empty(css.children.address_of_()):
  38         for css in list_for_each_entry('struct cgroup_subsys_state',
  39                                        css.children.address_of_(),
  40                                        'sibling'):
  41             name = prefix + '/' + css.cgroup.kn.name.string_().decode('utf-8')
  42             memcg = container_of(css, 'struct mem_cgroup', 'css')
  43             MEMCGS[css.cgroup.kn.id.value_()] = memcg
  44             find_memcg_ids(css, name)
  45
  46
  47 def is_root_cache(s):
  48     try:
  49         return False if s.memcg_params.root_cache else True
  50     except AttributeError:
  51         return True
  52
  53
  54 def cache_name(s):
  55     if is_root_cache(s):
  56         return s.name.string_().decode('utf-8')
  57     else:
  58         return s.memcg_params.root_cache.name.string_().decode('utf-8')
  59
  60
  61 # SLUB
  62
  63 def oo_order(s):
  64     return s.oo.x >> OO_SHIFT
  65
  66
  67 def oo_objects(s):
  68     return s.oo.x & OO_MASK
  69
  70
  71 def count_partial(n, fn):
  72     nr_objs = 0
  73     for slab in list_for_each_entry('struct slab', n.partial.address_of_(),
  74                                     'slab_list'):
  75          nr_objs += fn(slab)
  76     return nr_objs
  77
  78
  79 def count_free(slab):
  80     return slab.objects - slab.inuse
  81
  82
  83 def slub_get_slabinfo(s, cfg):
  84     nr_slabs = 0
  85     nr_objs = 0
  86     nr_free = 0
  87
  88     for node in range(cfg['nr_nodes']):
  89         n = s.node[node]
  90         nr_slabs += n.nr_slabs.counter.value_()
  91         nr_objs += n.total_objects.counter.value_()
  92         nr_free += count_partial(n, count_free)
  93
  94     return {'active_objs': nr_objs - nr_free,
  95             'num_objs': nr_objs,
  96             'active_slabs': nr_slabs,
  97             'num_slabs': nr_slabs,
  98             'objects_per_slab': oo_objects(s),
  99             'cache_order': oo_order(s),
 100             'limit': 0,
 101             'batchcount': 0,
 102             'shared': 0,
 103             'shared_avail': 0}
 104
 105
 106 def cache_show(s, cfg, objs):
 107     if cfg['allocator'] == 'SLUB':
 108         sinfo = slub_get_slabinfo(s, cfg)
 109     else:
 110         err('SLAB isn\'t supported yet')
 111
 112     if cfg['shared_slab_pages']:
 113         sinfo['active_objs'] = objs
 114         sinfo['num_objs'] = objs
 115
 116     print('%-17s %6lu %6lu %6u %4u %4d'
 117           ' : tunables %4u %4u %4u'
 118           ' : slabdata %6lu %6lu %6lu' % (
 119               cache_name(s), sinfo['active_objs'], sinfo['num_objs'],
 120               s.size, sinfo['objects_per_slab'], 1 << sinfo['cache_order'],
 121               sinfo['limit'], sinfo['batchcount'], sinfo['shared'],
 122               sinfo['active_slabs'], sinfo['num_slabs'],
 123               sinfo['shared_avail']))
 124
 125
 126 def detect_kernel_config():
 127     cfg = {}
 128
 129     cfg['nr_nodes'] = prog['nr_online_nodes'].value_()
 130
 131     if prog.type('struct kmem_cache').members[1].name == 'flags':
 132         cfg['allocator'] = 'SLUB'
 133     elif prog.type('struct kmem_cache').members[1].name == 'batchcount':
 134         cfg['allocator'] = 'SLAB'
 135     else:
 136         err('Can\'t determine the slab allocator')
 137
 138     cfg['shared_slab_pages'] = False
 139     try:
 140         if prog.type('struct obj_cgroup'):
 141             cfg['shared_slab_pages'] = True
 142     except:
 143         pass
 144
 145     return cfg
 146
 147
 148 def for_each_slab(prog):
 149     PGSlab = 1 << prog.constant('PG_slab')
 150     PGHead = 1 << prog.constant('PG_head')
 151
 152     for page in for_each_page(prog):
 153         try:
 154             if page.flags.value_() & PGSlab:
 155                 yield cast('struct slab *', page)
 156         except FaultError:
 157             pass
 158
 159
 160 def main():
 161     parser = argparse.ArgumentParser(description=DESC,
 162                                      formatter_class=
 163                                      argparse.RawTextHelpFormatter)
 164     parser.add_argument('cgroup', metavar='CGROUP',
 165                         help='Target memory cgroup')
 166     args = parser.parse_args()
 167
 168     try:
 169         cgroup_id = stat(args.cgroup).st_ino
 170         find_memcg_ids()
 171         memcg = MEMCGS[cgroup_id]
 172     except KeyError:
 173         err('Can\'t find the memory cgroup')
 174
 175     cfg = detect_kernel_config()
 176
 177     print('# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>'
 178           ' : tunables <limit> <batchcount> <sharedfactor>'
 179           ' : slabdata <active_slabs> <num_slabs> <sharedavail>')
 180
 181     if cfg['shared_slab_pages']:
 182         obj_cgroups = set()
 183         stats = {}
 184         caches = {}
 185
 186         # find memcg pointers belonging to the specified cgroup
 187         obj_cgroups.add(memcg.objcg.value_())
 188         for ptr in list_for_each_entry('struct obj_cgroup',
 189                                        memcg.objcg_list.address_of_(),
 190                                        'list'):
 191             obj_cgroups.add(ptr.value_())
 192
 193         # look over all slab folios and look for objects belonging
 194         # to the given memory cgroup
 195         for slab in for_each_slab(prog):
 196             objcg_vec_raw = slab.memcg_data.value_()
 197             if objcg_vec_raw == 0:
 198                 continue
 199             cache = slab.slab_cache
 200             if not cache:
 201                 continue
 202             addr = cache.value_()
 203             caches[addr] = cache
 204             # clear the lowest bit to get the true obj_cgroups
 205             objcg_vec = Object(prog, 'struct obj_cgroup **',
 206                                value=objcg_vec_raw & ~1)
 207
 208             if addr not in stats:
 209                 stats[addr] = 0
 210
 211             for i in range(oo_objects(cache)):
 212                 if objcg_vec[i].value_() in obj_cgroups:
 213                     stats[addr] += 1
 214
 215         for addr in caches:
 216             if stats[addr] > 0:
 217                 cache_show(caches[addr], cfg, stats[addr])
 218
 219     else:
 220         for s in list_for_each_entry('struct kmem_cache',
 221                                      memcg.kmem_caches.address_of_(),
 222                                      'memcg_params.kmem_caches_node'):
 223             cache_show(s, cfg, None)
 224
 225
 226 main()