On Thu, Jan 31, 2019 at 10:38:01AM +0100, Martynas Pumputis wrote:
> Previously, memory allocated for a map was not accounted. Therefore,
> this memory could not be taken into consideration by the cgroups
> memory controller.
>
> This patch introduces the "BPF_F_ACCOUNT_MEM" flag which enables
> the memory accounting for a map, and it can be set during
> the map creation ("BPF_MAP_CREATE") in "map_flags".
>
> When enabled, we account only that amount of memory which is charged
> against the "RLIMIT_MEMLOCK" limit.
>
> To validate the change, first we create the memory cgroup-v1 "test-map":
>
> # mkdir /sys/fs/cgroup/memory/test-map
>
> And then we run the following program against the cgroup:
>
> $ cat test_map.c
> <..>
> int main() {
> usleep(3 * 1000000);
> assert(bpf_create_map(BPF_MAP_TYPE_HASH, 8, 16, 65536, 0) > 0);
> usleep(3 * 1000000);
> }
> # cgexec -g memory:test-map ./test_map &
> # cat /sys/fs/cgroup/memory/test-map/memory{,.kmem}.usage_in_bytes
> 397312
> 258048
>
> <after 3 sec the map has been created>
>
> # bpftool map list
> 19: hash flags 0x0
> key 8B value 16B max_entries 65536 memlock 5771264B
> # cat /sys/fs/cgroup/memory/test-map/memory{,.kmem}.usage_in_bytes
> 401408
> 262144
>
> As we can see, the memory allocated for map is not accounted, as
> 397312B + 5771264B > 401408B.
>
> Next, we enabled the accounting and re-run the test:
>
> $ cat test_map.c
> <..>
> int main() {
> usleep(3 * 1000000);
> assert(bpf_create_map(BPF_MAP_TYPE_HASH, 8, 16, 65536,
> BPF_F_ACCOUNT_MEM) > 0);
> usleep(3 * 1000000);
> }
> # cgexec -g memory:test-map ./test_map &
> # cat /sys/fs/cgroup/memory/test-map/memory{,.kmem}.usage_in_bytes
> 450560
> 307200
>
> <after 3 sec the map has been created>
>
> # bpftool map list
> 20: hash flags 0x80
> key 8B value 16B max_entries 65536 memlock 5771264B
> # cat /sys/fs/cgroup/memory/test-map/memory{,.kmem}.usage_in_bytes
> 6221824
> 6078464
>
> This time, the memory (including kmem) is accounted, as
> 450560B + 5771264B <= 6221824B
>
> Acked-by: Yonghong Song <[email protected]>
> Signed-off-by: Martynas Pumputis <[email protected]>
see my reply in other thread.
