On Fri, Nov 20, 2020 at 06:52:27PM -0800, Alexei Starovoitov wrote: > On Thu, Nov 19, 2020 at 09:37:52AM -0800, Roman Gushchin wrote: > > static void bpf_map_put_uref(struct bpf_map *map) > > @@ -619,7 +562,7 @@ static void bpf_map_show_fdinfo(struct seq_file *m, struct file *filp) > > "value_size:\t%u\n" > > "max_entries:\t%u\n" > > "map_flags:\t%#x\n" > > - "memlock:\t%llu\n" > > + "memlock:\t%llu\n" /* deprecated */ > > "map_id:\t%u\n" > > "frozen:\t%u\n", > > map->map_type, > > @@ -627,7 +570,7 @@ static void bpf_map_show_fdinfo(struct seq_file *m, struct file *filp) > > map->value_size, > > map->max_entries, > > map->map_flags, > > - map->memory.pages * 1ULL << PAGE_SHIFT, > > + 0LLU, > > The set looks great to me overall, but above change is problematic. > There are tools out there that read this value. > Returning zero might cause oncall alarms to trigger. > I think we can be more accurate here. > Instead of zero the kernel can return > round_up(max_entries * round_up(key_size + value_size, 8), PAGE_SIZE) > It's not the same as before, but at least the numbers won't suddenly > go to zero and comparison between maps is still relevant. > Of course we can introduce a page size calculating callback per map type, > but imo that would be overkill. These monitoring tools don't care about > precise number, but rather about relative value and growth from one > version of the application to another. > > If Daniel doesn't find other issues this can be fixed in the follow up. Makes total sense. I'll prepare a follow-up patch. Thanks!
