| Message ID | 20220810151322.16163-1-laoar.shao@gmail.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | bpf: Introduce selectable memcg for bpf map | expand |
On Wed, Aug 10, 2022 at 11:13 PM Yafang Shao <laoar.shao@gmail.com> wrote: > > On our production environment, we may load, run and pin bpf programs and > maps in containers. For example, some of our networking bpf programs and > maps are loaded and pinned by a process running in a container on our > k8s environment. In this container, there're also running some other > user applications which watch the networking configurations from remote > servers and update them on this local host, log the error events, monitor > the traffic, and do some other stuffs. Sometimes we may need to update > these user applications to a new release, and in this update process we > will destroy the old container and then start a new genration. In order not > to interrupt the bpf programs in the update process, we will pin the bpf > programs and maps in bpffs. That is the background and use case on our > production environment. > > After switching to memcg-based bpf memory accounting to limit the bpf > memory, some unexpected issues jumped out at us. > 1. The memory usage is not consistent between the first generation and > new generations. > 2. After the first generation is destroyed, the bpf memory can't be > limited if the bpf maps are not preallocated, because they will be > reparented. > > This patchset tries to resolve these issues by introducing an > independent memcg to limit the bpf memory. > > In the bpf map creation, we can assign a specific memcg instead of using > the current memcg. That makes it flexible in containized environment. > For example, if we want to limit the pinned bpf maps, we can use below > hierarchy, > > Shared resources Private resources > > bpf-memcg k8s-memcg > / \ / > bpf-bar-memcg bpf-foo-memcg srv-foo-memcg > | / \ > (charged) (not charged) (charged) > | / \ > | / \ > bpf-foo-{progs, maps} srv-foo > > srv-foo loads and pins bpf-foo-{progs, maps}, but they are charged to an > independent memcg (bpf-foo-memcg) instead of srv-foo's memcg > (srv-foo-memcg). > > Pls. note that there may be no process in bpf-foo-memcg, that means it > can be rmdir-ed by root user currently. Meanwhile we don't forcefully > destroy a memcg if it doesn't have any residents. So this hierarchy is > acceptible. > > In order to make the memcg of bpf maps seletectable, this patchset > introduces some memory allocation wrappers to allocate map related > memory. In these wrappers, it will get the memcg from the map and then > charge the allocated pages or objs. > > Currenly it only supports for bpf map, and we can extend it to bpf prog > as well. It only supports for cgroup2 now, but we can make an additional > change in cgroup_get_from_fd() to support it for cgroup1. > > The observebility can also be supported in the next step, for example, > showing the bpf map's memcg by 'bpftool map show' or even showing which > maps are charged to a specific memcg by 'bpftool cgroup show'. > Furthermore, we may also show an accurate memory size of a bpf map > instead of an estimated memory size in 'bpftool map show' in the future. > > RFC->v1: > - get rid of bpf_map container wrapper (Alexei) > - add the new field into the end of struct (Alexei) > - get rid of BPF_F_SELECTABLE_MEMCG (Alexei) > - save memcg in bpf_map_init_from_attr > - introduce bpf_ringbuf_pages_{alloc,free} and keep them inside > kernel/bpf/ringbuf.c (Andrii) > > Yafang Shao (15): > bpf: Remove unneeded memset in queue_stack_map creation > bpf: Use bpf_map_area_free instread of kvfree > bpf: Make __GFP_NOWARN consistent in bpf map creation > bpf: Use bpf_map_area_alloc consistently on bpf map creation > bpf: Fix incorrect mem_cgroup_put > bpf: Define bpf_map_{get,put}_memcg for !CONFIG_MEMCG_KMEM > bpf: Call bpf_map_init_from_attr() immediately after map creation > bpf: Save memcg in bpf_map_init_from_attr() > bpf: Use scoped-based charge in bpf_map_area_alloc > bpf: Introduce new helpers bpf_ringbuf_pages_{alloc,free} > bpf: Use bpf_map_kzalloc in arraymap > bpf: Use bpf_map_kvcalloc in bpf_local_storage > mm, memcg: Add new helper get_obj_cgroup_from_cgroup > bpf: Add return value for bpf_map_init_from_attr > bpf: Introduce selectable memcg for bpf map > > include/linux/bpf.h | 43 ++++++++++++- > include/linux/memcontrol.h | 11 ++++ > include/uapi/linux/bpf.h | 1 + > kernel/bpf/arraymap.c | 34 ++++++----- > kernel/bpf/bloom_filter.c | 11 +++- > kernel/bpf/bpf_local_storage.c | 17 ++++-- > kernel/bpf/bpf_struct_ops.c | 19 +++--- > kernel/bpf/cpumap.c | 17 ++++-- > kernel/bpf/devmap.c | 30 ++++++---- > kernel/bpf/hashtab.c | 26 ++++---- > kernel/bpf/local_storage.c | 12 ++-- > kernel/bpf/lpm_trie.c | 12 +++- > kernel/bpf/offload.c | 12 ++-- > kernel/bpf/queue_stack_maps.c | 13 ++-- > kernel/bpf/reuseport_array.c | 11 +++- > kernel/bpf/ringbuf.c | 104 ++++++++++++++++++++++---------- > kernel/bpf/stackmap.c | 13 ++-- > kernel/bpf/syscall.c | 133 ++++++++++++++++++++++++++++------------- > mm/memcontrol.c | 41 +++++++++++++ > net/core/sock_map.c | 30 ++++++---- > net/xdp/xskmap.c | 12 +++- > tools/include/uapi/linux/bpf.h | 1 + > tools/lib/bpf/bpf.c | 3 +- > tools/lib/bpf/bpf.h | 3 +- > tools/lib/bpf/gen_loader.c | 2 +- > tools/lib/bpf/libbpf.c | 2 + > tools/lib/bpf/skel_internal.h | 2 +- > 27 files changed, 436 insertions(+), 179 deletions(-) > > -- > 1.8.3.1 > Ah, this series is incomplete. Pls see the update one. https://lore.kernel.org/bpf/20220810151840.16394-1-laoar.shao@gmail.com/T/#t -- Regards Yafang
On our production environment, we may load, run and pin bpf programs and maps in containers. For example, some of our networking bpf programs and maps are loaded and pinned by a process running in a container on our k8s environment. In this container, there're also running some other user applications which watch the networking configurations from remote servers and update them on this local host, log the error events, monitor the traffic, and do some other stuffs. Sometimes we may need to update these user applications to a new release, and in this update process we will destroy the old container and then start a new genration. In order not to interrupt the bpf programs in the update process, we will pin the bpf programs and maps in bpffs. That is the background and use case on our production environment. After switching to memcg-based bpf memory accounting to limit the bpf memory, some unexpected issues jumped out at us. 1. The memory usage is not consistent between the first generation and new generations. 2. After the first generation is destroyed, the bpf memory can't be limited if the bpf maps are not preallocated, because they will be reparented. This patchset tries to resolve these issues by introducing an independent memcg to limit the bpf memory. In the bpf map creation, we can assign a specific memcg instead of using the current memcg. That makes it flexible in containized environment. For example, if we want to limit the pinned bpf maps, we can use below hierarchy, Shared resources Private resources bpf-memcg k8s-memcg / \ / bpf-bar-memcg bpf-foo-memcg srv-foo-memcg | / \ (charged) (not charged) (charged) | / \ | / \ bpf-foo-{progs, maps} srv-foo srv-foo loads and pins bpf-foo-{progs, maps}, but they are charged to an independent memcg (bpf-foo-memcg) instead of srv-foo's memcg (srv-foo-memcg). Pls. note that there may be no process in bpf-foo-memcg, that means it can be rmdir-ed by root user currently. Meanwhile we don't forcefully destroy a memcg if it doesn't have any residents. So this hierarchy is acceptible. In order to make the memcg of bpf maps seletectable, this patchset introduces some memory allocation wrappers to allocate map related memory. In these wrappers, it will get the memcg from the map and then charge the allocated pages or objs. Currenly it only supports for bpf map, and we can extend it to bpf prog as well. It only supports for cgroup2 now, but we can make an additional change in cgroup_get_from_fd() to support it for cgroup1. The observebility can also be supported in the next step, for example, showing the bpf map's memcg by 'bpftool map show' or even showing which maps are charged to a specific memcg by 'bpftool cgroup show'. Furthermore, we may also show an accurate memory size of a bpf map instead of an estimated memory size in 'bpftool map show' in the future. RFC->v1: - get rid of bpf_map container wrapper (Alexei) - add the new field into the end of struct (Alexei) - get rid of BPF_F_SELECTABLE_MEMCG (Alexei) - save memcg in bpf_map_init_from_attr - introduce bpf_ringbuf_pages_{alloc,free} and keep them inside kernel/bpf/ringbuf.c (Andrii) Yafang Shao (15): bpf: Remove unneeded memset in queue_stack_map creation bpf: Use bpf_map_area_free instread of kvfree bpf: Make __GFP_NOWARN consistent in bpf map creation bpf: Use bpf_map_area_alloc consistently on bpf map creation bpf: Fix incorrect mem_cgroup_put bpf: Define bpf_map_{get,put}_memcg for !CONFIG_MEMCG_KMEM bpf: Call bpf_map_init_from_attr() immediately after map creation bpf: Save memcg in bpf_map_init_from_attr() bpf: Use scoped-based charge in bpf_map_area_alloc bpf: Introduce new helpers bpf_ringbuf_pages_{alloc,free} bpf: Use bpf_map_kzalloc in arraymap bpf: Use bpf_map_kvcalloc in bpf_local_storage mm, memcg: Add new helper get_obj_cgroup_from_cgroup bpf: Add return value for bpf_map_init_from_attr bpf: Introduce selectable memcg for bpf map include/linux/bpf.h | 43 ++++++++++++- include/linux/memcontrol.h | 11 ++++ include/uapi/linux/bpf.h | 1 + kernel/bpf/arraymap.c | 34 ++++++----- kernel/bpf/bloom_filter.c | 11 +++- kernel/bpf/bpf_local_storage.c | 17 ++++-- kernel/bpf/bpf_struct_ops.c | 19 +++--- kernel/bpf/cpumap.c | 17 ++++-- kernel/bpf/devmap.c | 30 ++++++---- kernel/bpf/hashtab.c | 26 ++++---- kernel/bpf/local_storage.c | 12 ++-- kernel/bpf/lpm_trie.c | 12 +++- kernel/bpf/offload.c | 12 ++-- kernel/bpf/queue_stack_maps.c | 13 ++-- kernel/bpf/reuseport_array.c | 11 +++- kernel/bpf/ringbuf.c | 104 ++++++++++++++++++++++---------- kernel/bpf/stackmap.c | 13 ++-- kernel/bpf/syscall.c | 133 ++++++++++++++++++++++++++++------------- mm/memcontrol.c | 41 +++++++++++++ net/core/sock_map.c | 30 ++++++---- net/xdp/xskmap.c | 12 +++- tools/include/uapi/linux/bpf.h | 1 + tools/lib/bpf/bpf.c | 3 +- tools/lib/bpf/bpf.h | 3 +- tools/lib/bpf/gen_loader.c | 2 +- tools/lib/bpf/libbpf.c | 2 + tools/lib/bpf/skel_internal.h | 2 +- 27 files changed, 436 insertions(+), 179 deletions(-)