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/memcg_slabinfo.py /sys/fs/cgroup/user.slice/user-111017.slice/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> Acked-by: Tejun Heo <tj@xxxxxxxxxx> --- tools/cgroup/memcg_slabinfo.py | 226 +++++++++++++++++++++++++++++++++ 1 file changed, 226 insertions(+) create mode 100644 tools/cgroup/memcg_slabinfo.py diff --git a/tools/cgroup/memcg_slabinfo.py b/tools/cgroup/memcg_slabinfo.py new file mode 100644 index 000000000000..c4225ed63565 --- /dev/null +++ b/tools/cgroup/memcg_slabinfo.py @@ -0,0 +1,226 @@ +#!/usr/bin/env drgn +# +# Copyright (C) 2020 Roman Gushchin <guro@xxxxxx> +# 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 + + +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_pages = 0 + for page in list_for_each_entry('struct page', n.partial.address_of_(), + 'lru'): + nr_pages += fn(page) + return nr_pages + + +def count_free(page): + return page.objects - page.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][1] == 'flags': + cfg['allocator'] = 'SLUB' + elif prog.type('struct kmem_cache').members[1][1] == '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_page(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 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 pages, belonging to non-root memcgs + # and look for objects belonging to the given memory cgroup + for page in for_each_slab_page(prog): + objcg_vec_raw = page.obj_cgroups.value_() + if objcg_vec_raw == 0: + continue + cache = page.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, page.obj_cgroups.type_, + 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() -- 2.26.2
