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charset="UTF-8" X-Rspam-User: X-Rspamd-Queue-Id: 7E8BAC0004 X-Rspamd-Server: rspam01 X-Stat-Signature: arzh5ifoeh7qydgd47r4p1h3ye5buqpn X-HE-Tag: 1675146539-782841 X-HE-Meta: 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 t/FyqK4O 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Jan 30, 2023 at 9:14 PM Uladzislau Rezki wrote: > > On Sat, Jan 28, 2023 at 07:49:08PM +0800, Yafang Shao wrote: > > On Thu, Jan 26, 2023 at 1:45 PM Alexei Starovoitov > > wrote: > > > > > > On Tue, Jan 17, 2023 at 10:49 PM Yafang Shao wrote: > > > > > > I just don't want to add many if-elses or switch-cases into > > > > > > bpf_map_memory_footprint(), because I think it is a little ugly. > > > > > > Introducing a new map ops could make it more clear. For example, > > > > > > static unsigned long bpf_map_memory_footprint(const struct bpf_map *map) > > > > > > { > > > > > > unsigned long size; > > > > > > > > > > > > if (map->ops->map_mem_footprint) > > > > > > return map->ops->map_mem_footprint(map); > > > > > > > > > > > > size = round_up(map->key_size + bpf_map_value_size(map), 8); > > > > > > return round_up(map->max_entries * size, PAGE_SIZE); > > > > > > } > > > > > > > > > > It is also ugly, because bpf_map_value_size() already has if-stmt. > > > > > I prefer to keep all estimates in one place. > > > > > There is no need to be 100% accurate. > > > > > > > > Per my investigation, it can be almost accurate with little effort. > > > > Take the htab for example, > > > > static unsigned long htab_mem_footprint(const struct bpf_map *map) > > > > { > > > > struct bpf_htab *htab = container_of(map, struct bpf_htab, map); > > > > unsigned long size = 0; > > > > > > > > if (!htab_is_prealloc(htab)) { > > > > size += htab_elements_size(htab); > > > > } > > > > size += kvsize(htab->elems); > > > > size += percpu_size(htab->extra_elems); > > > > size += kvsize(htab->buckets); > > > > size += bpf_mem_alloc_size(&htab->pcpu_ma); > > > > size += bpf_mem_alloc_size(&htab->ma); > > > > if (htab->use_percpu_counter) > > > > size += percpu_size(htab->pcount.counters); > > > > size += percpu_size(htab->map_locked[i]) * HASHTAB_MAP_LOCK_COUNT; > > > > size += kvsize(htab); > > > > return size; > > > > } > > > > > > Please don't. > > > Above doesn't look maintainable. > > > > It is similar to htab_map_free(). These pointers are the pointers > > which will be freed in map_free(). > > We just need to keep map_mem_footprint() in sync with map_free(). It > > won't be a problem for maintenance. > > > > > Look at kvsize(htab). Do you really care about hundred bytes? > > > Just accept that there will be a small constant difference > > > between what show_fdinfo reports and the real memory. > > > > The point is we don't have a clear idea what the margin is. > > > > > You cannot make it 100%. > > > There is kfence that will allocate 4k though you asked kmalloc(8). > > > > > > > We already have ksize()[1], which covers the kfence. > > > > [1]. https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/tree/mm/slab_common.c#n1431 > > > > > > We just need to get the real memory size from the pointer instead of > > > > calculating the size again. > > > > For non-preallocated htab, it is a little trouble to get the element > > > > size (not the unit_size), but it won't be a big deal. > > > > > > You'd have to convince mm folks that kvsize() is worth doing. > > > I don't think it will be easy. > > > > > > > As I mentioned above, we already have ksize(), so we only need to > > introduce vsize(). Per my understanding, we can simply use > > vm_struct->size to get the vmalloc size, see also the patch #5 in this > > patchset[2]. > > > > Andrew, Uladzislau, Christoph, do you have any comments on this newly > > introduced vsize()[2] ? > > > > [2]. https://lore.kernel.org/bpf/20230112155326.26902-6-laoar.shao@gmail.com/ > > > > +/* Report full size of underlying allocation of a vmalloc'ed addr */ > +static inline size_t vsize(const void *addr) > +{ > + struct vm_struct *area; > + > + if (!addr) > + return 0; > + > + area = find_vm_area(addr); > + if (unlikely(!area)) > + return 0; > + > + return area->size; > +} > > > You can not access area after the lock is dropped. We do not have any > ref counters for VA objects. Therefore it should be done like below: > > > > spin_lock(&vmap_area_lock); > va = __find_vmap_area(addr, &vmap_area_root); > if (va && va->vm) > va_size = va->vm->size; > spin_unlock(&vmap_area_lock); > > return va_size; > > Ah, it should take this global lock. I missed that. Many thanks for the detailed explanation. -- Regards Yafang