From: Hui Zhu <[email protected]> Add a sample program to demonstrate a practical use case for the `memcg_bpf_ops` feature: priority-based memory throttling.
The sample consists of a BPF program and a userspace loader: 1. memcg.bpf.c: A BPF program that monitors PGFAULT events on a high-priority cgroup. When activity exceeds a threshold, it uses the `get_high_delay_ms`, `below_low`, or `below_min` hooks to apply pressure on a low-priority cgroup. 2. memcg.c: A userspace loader that configures and attaches the BPF program. It takes command-line arguments for the high and low priority cgroup paths, a pressure threshold, and the desired throttling delay (`over_high_ms`). This provides a clear, working example of how to implement a dynamic, priority-aware memory management policy. A user can create two cgroups, run workloads of different priorities, and observe the low-priority workload being throttled to protect the high-priority one. Example usage: # ./memcg --low_path /sys/fs/cgroup/low \ # --high_path /sys/fs/cgroup/high \ # --threshold 100 --over_high_ms 1024 Signed-off-by: Geliang Tang <[email protected]> Signed-off-by: Hui Zhu <[email protected]> --- MAINTAINERS | 2 + samples/bpf/.gitignore | 1 + samples/bpf/Makefile | 8 +- samples/bpf/memcg.bpf.c | 129 ++++++++++++++++ samples/bpf/memcg.c | 327 ++++++++++++++++++++++++++++++++++++++++ 5 files changed, 466 insertions(+), 1 deletion(-) create mode 100644 samples/bpf/memcg.bpf.c create mode 100644 samples/bpf/memcg.c diff --git a/MAINTAINERS b/MAINTAINERS index 7e07bb330eae..819ef271e011 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -6470,6 +6470,8 @@ F: mm/memcontrol-v1.c F: mm/memcontrol-v1.h F: mm/page_counter.c F: mm/swap_cgroup.c +F: samples/bpf/memcg.bpf.c +F: samples/bpf/memcg.c F: samples/cgroup/* F: tools/testing/selftests/bpf/prog_tests/memcg_ops.c F: tools/testing/selftests/bpf/progs/memcg_ops.c diff --git a/samples/bpf/.gitignore b/samples/bpf/.gitignore index 0002cd359fb1..0de6569cdefd 100644 --- a/samples/bpf/.gitignore +++ b/samples/bpf/.gitignore @@ -49,3 +49,4 @@ iperf.* /vmlinux.h /bpftool/ /libbpf/ +memcg diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 95a4fa1f1e44..b00698bdc53b 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -37,6 +37,7 @@ tprogs-y += xdp_fwd tprogs-y += task_fd_query tprogs-y += ibumad tprogs-y += hbm +tprogs-y += memcg # Libbpf dependencies LIBBPF_SRC = $(TOOLS_PATH)/lib/bpf @@ -122,6 +123,7 @@ always-y += task_fd_query_kern.o always-y += ibumad_kern.o always-y += hbm_out_kern.o always-y += hbm_edt_kern.o +always-y += memcg.bpf.o COMMON_CFLAGS = $(TPROGS_USER_CFLAGS) TPROGS_LDFLAGS = $(TPROGS_USER_LDFLAGS) @@ -289,6 +291,8 @@ $(obj)/hbm_out_kern.o: $(src)/hbm.h $(src)/hbm_kern.h $(obj)/hbm.o: $(src)/hbm.h $(obj)/hbm_edt_kern.o: $(src)/hbm.h $(src)/hbm_kern.h +memcg: $(obj)/memcg.skel.h + # Override includes for xdp_sample_user.o because $(srctree)/usr/include in # TPROGS_CFLAGS causes conflicts XDP_SAMPLE_CFLAGS += -Wall -O2 \ @@ -347,11 +351,13 @@ $(obj)/%.bpf.o: $(src)/%.bpf.c $(obj)/vmlinux.h $(src)/xdp_sample.bpf.h $(src)/x -I$(LIBBPF_INCLUDE) $(CLANG_SYS_INCLUDES) \ -c $(filter %.bpf.c,$^) -o $@ -LINKED_SKELS := xdp_router_ipv4.skel.h +LINKED_SKELS := xdp_router_ipv4.skel.h memcg.skel.h clean-files += $(LINKED_SKELS) xdp_router_ipv4.skel.h-deps := xdp_router_ipv4.bpf.o xdp_sample.bpf.o +memcg.skel.h-deps := memcg.bpf.o + LINKED_BPF_SRCS := $(patsubst %.bpf.o,%.bpf.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps))) BPF_SRCS_LINKED := $(notdir $(wildcard $(src)/*.bpf.c)) diff --git a/samples/bpf/memcg.bpf.c b/samples/bpf/memcg.bpf.c new file mode 100644 index 000000000000..44087a206a61 --- /dev/null +++ b/samples/bpf/memcg.bpf.c @@ -0,0 +1,129 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include "vmlinux.h" +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +#define ONE_SECOND_NS 1000000000 + +struct local_config { + u64 threshold; + u64 high_cgroup_id; + bool use_below_low; + bool use_below_min; + unsigned int over_high_ms; +} local_config; + +struct AggregationData { + u64 sum; + u64 window_start_ts; +}; + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(max_entries, 1); + __type(key, u32); + __type(value, struct AggregationData); +} aggregation_map SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(max_entries, 1); + __type(key, u32); + __type(value, u64); +} trigger_ts_map SEC(".maps"); + +SEC("tp/memcg/count_memcg_events") +int +handle_count_memcg_events(struct trace_event_raw_memcg_rstat_events *ctx) +{ + u32 key = 0; + struct AggregationData *data; + u64 current_ts; + + if (ctx->id != local_config.high_cgroup_id || + (ctx->item != PGFAULT)) + goto out; + + data = bpf_map_lookup_elem(&aggregation_map, &key); + if (!data) + goto out; + + current_ts = bpf_ktime_get_ns(); + + if (current_ts - data->window_start_ts < ONE_SECOND_NS) { + data->sum += ctx->val; + } else { + data->window_start_ts = current_ts; + data->sum = ctx->val; + } + + if (data->sum > local_config.threshold) { + bpf_map_update_elem(&trigger_ts_map, &key, ¤t_ts, + BPF_ANY); + data->sum = 0; + data->window_start_ts = current_ts; + } + +out: + return 0; +} + +static bool need_threshold(void) +{ + u32 key = 0; + u64 *trigger_ts; + bool ret = false; + + trigger_ts = bpf_map_lookup_elem(&trigger_ts_map, &key); + if (!trigger_ts || *trigger_ts == 0) + goto out; + + u64 current_ts = bpf_ktime_get_ns(); + + if (current_ts - *trigger_ts < ONE_SECOND_NS) + ret = true; + +out: + return ret; +} + +SEC("struct_ops/below_low") +unsigned int below_low_impl(struct mem_cgroup *memcg) +{ + if (!local_config.use_below_low) + return false; + + return need_threshold(); +} + +SEC("struct_ops/below_min") +unsigned int below_min_impl(struct mem_cgroup *memcg) +{ + if (!local_config.use_below_min) + return false; + + return need_threshold(); +} + +SEC("struct_ops/get_high_delay_ms") +unsigned int get_high_delay_ms_impl(struct mem_cgroup *memcg) +{ + if (local_config.over_high_ms && need_threshold()) + return local_config.over_high_ms; + + return 0; +} + +SEC(".struct_ops.link") +struct memcg_bpf_ops high_mcg_ops = { + .below_low = (void *)below_low_impl, + .below_min = (void *)below_min_impl, +}; + +SEC(".struct_ops.link") +struct memcg_bpf_ops low_mcg_ops = { + .get_high_delay_ms = (void *)get_high_delay_ms_impl, +}; + +char LICENSE[] SEC("license") = "GPL"; diff --git a/samples/bpf/memcg.c b/samples/bpf/memcg.c new file mode 100644 index 000000000000..6d59a722f581 --- /dev/null +++ b/samples/bpf/memcg.c @@ -0,0 +1,327 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <stdio.h> +#include <stdlib.h> +#include <stdint.h> +#include <string.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <unistd.h> +#include <errno.h> +#include <unistd.h> +#include <signal.h> +#include <stdbool.h> +#include <getopt.h> +#include <bpf/bpf.h> +#include <bpf/libbpf.h> + +#ifndef __MEMCG_RSTAT_SIMPLE_BPF_SKEL_H__ +#define u64 uint64_t +#endif + +struct local_config { + u64 threshold; + u64 high_cgroup_id; + bool use_below_low; + bool use_below_min; + unsigned int over_high_ms; +} local_config; + +#include "memcg.skel.h" + +static bool exiting; + +static void sig_handler(int sig) +{ + exiting = true; +} + +static void usage(char *name) +{ + fprintf(stderr, + "Usage: %s --low_path=<path> --high_path=<path> \\\n" + " --threshold=<value> [OPTIONS]\n\n", + name); + fprintf(stderr, "Required arguments:\n"); + fprintf(stderr, + " -l, --low_path=PATH Low priority memcgroup path\n"); + fprintf(stderr, + " -g, --high_path=PATH High priority memcgroup path\n"); + fprintf(stderr, + " -t, --threshold=VALUE The sum of 'val' PGSCAN of\n"); + fprintf(stderr, + " high priority memcgroup in\n"); + fprintf(stderr, + " 1 sec to trigger low priority\n"); + fprintf(stderr, + " cgroup over_high\n\n"); + fprintf(stderr, "Optional arguments:\n"); + fprintf(stderr, " -o, --over_high_ms=VALUE\n"); + fprintf(stderr, + " Low_path over_high_ms value\n"); + fprintf(stderr, + " (default: 0)\n"); + fprintf(stderr, " -L, --use_below_low Enable use_below_low flag\n"); + fprintf(stderr, " -M, --use_below_min Enable use_below_min flag\n"); + fprintf(stderr, + " -O, --allow_override Enable BPF_F_ALLOW_OVERRIDE\n"); + fprintf(stderr, + " flag\n"); + fprintf(stderr, " -h, --help Show this help message\n\n"); + fprintf(stderr, "Examples:\n"); + fprintf(stderr, " # Using long options:\n"); + fprintf(stderr, " %s --low_path=/sys/fs/cgroup/low \\\n", name); + fprintf(stderr, " --high_path=/sys/fs/cgroup/high \\\n"); + fprintf(stderr, " --threshold=1000 --over_high_ms=500 \\\n" + " --use_below_low\n\n"); + fprintf(stderr, " # Using short options:\n"); + fprintf(stderr, " %s -l /sys/fs/cgroup/low \\\n" + " -g /sys/fs/cgroup/high \\\n", + name); + fprintf(stderr, " -t 1000 -o 500 -L -M\n"); +} + +static uint64_t get_cgroup_id(const char *cgroup_path) +{ + struct stat st; + + if (cgroup_path == NULL) { + fprintf(stderr, "Error: cgroup_path is NULL\n"); + return 0; + } + + if (stat(cgroup_path, &st) < 0) { + fprintf(stderr, "Error: stat(%s) failed: %d\n", + cgroup_path, errno); + return 0; + } + + return (uint64_t)st.st_ino; +} + +int main(int argc, char **argv) +{ + int low_cgroup_fd = -1, high_cgroup_fd = -1; + uint64_t threshold = 0, high_cgroup_id; + unsigned int over_high_ms = 0; + bool use_below_low = false, use_below_min = false; + __u32 opts_flags = 0; + const char *low_path = NULL; + const char *high_path = NULL; + const char *bpf_obj_file = "memcg.bpf.o"; + struct bpf_object *obj = NULL; + struct bpf_program *prog = NULL; + struct bpf_link *link = NULL, *link_low = NULL, *link_high = NULL; + struct bpf_map *map; + struct memcg__bss *bss_data; + DECLARE_LIBBPF_OPTS(bpf_struct_ops_opts, opts); + int err = -EINVAL; + int map_fd; + int opt; + int option_index = 0; + + static struct option long_options[] = { + {"low_path", required_argument, 0, 'l'}, + {"high_path", required_argument, 0, 'g'}, + {"threshold", required_argument, 0, 't'}, + {"over_high_ms", required_argument, 0, 'o'}, + {"use_below_low", no_argument, 0, 'L'}, + {"use_below_min", no_argument, 0, 'M'}, + {"allow_override", no_argument, 0, 'O'}, + {"help", no_argument, 0, 'h'}, + {0, 0, 0, 0 } + }; + + while ((opt = getopt_long(argc, argv, "l:g:t:o:LMOh", + long_options, &option_index)) != -1) { + switch (opt) { + case 'l': + low_path = optarg; + break; + case 'g': + high_path = optarg; + break; + case 't': + threshold = strtoull(optarg, NULL, 10); + break; + case 'o': + over_high_ms = strtoull(optarg, NULL, 10); + break; + case 'L': + use_below_low = true; + break; + case 'M': + use_below_min = true; + break; + case 'O': + opts_flags = BPF_F_ALLOW_OVERRIDE; + break; + case 'h': + usage(argv[0]); + return 0; + default: + usage(argv[0]); + return -EINVAL; + } + } + + if (!low_path || !high_path || !threshold) { + fprintf(stderr, + "ERROR: Missing required arguments\n\n"); + usage(argv[0]); + goto out; + } + + low_cgroup_fd = open(low_path, O_RDONLY); + if (low_cgroup_fd < 0) { + fprintf(stderr, + "ERROR: open low cgroup '%s' failed: %d\n", + low_path, errno); + err = -errno; + goto out; + } + + high_cgroup_id = get_cgroup_id(high_path); + if (!high_cgroup_id) + goto out; + high_cgroup_fd = open(high_path, O_RDONLY); + if (high_cgroup_fd < 0) { + fprintf(stderr, + "ERROR: open high cgroup '%s' failed: %d\n", + high_path, errno); + err = -errno; + goto out; + } + + obj = bpf_object__open_file(bpf_obj_file, NULL); + err = libbpf_get_error(obj); + if (err) { + fprintf(stderr, + "ERROR: opening BPF object file '%s' failed: %d\n", + bpf_obj_file, err); + goto out; + } + + map = bpf_object__find_map_by_name(obj, ".bss"); + if (!map) { + fprintf(stderr, "ERROR: Failed to find .data map\n"); + err = -ESRCH; + goto out; + } + + err = bpf_object__load(obj); + if (err) { + fprintf(stderr, + "ERROR: loading BPF object file failed: %d\n", + err); + goto out; + } + + map_fd = bpf_map__fd(map); + bss_data = malloc(bpf_map__value_size(map)); + if (bss_data) { + __u32 key = 0; + + memset(bss_data, 0, sizeof(struct local_config)); + bss_data->local_config.high_cgroup_id = high_cgroup_id; + bss_data->local_config.threshold = threshold; + bss_data->local_config.over_high_ms = over_high_ms; + bss_data->local_config.use_below_low = use_below_low; + bss_data->local_config.use_below_min = use_below_min; + + err = bpf_map_update_elem(map_fd, &key, bss_data, BPF_EXIST); + free(bss_data); + if (err) { + fprintf(stderr, + "ERROR: update config failed: %d\n", + err); + goto out; + } + } else { + fprintf(stderr, + "ERROR: allocate memory failed\n"); + err = -ENOMEM; + goto out; + } + + prog = bpf_object__find_program_by_name(obj, + "handle_count_memcg_events"); + if (!prog) { + fprintf(stderr, + "ERROR: finding a prog in BPF object file failed\n"); + goto out; + } + + link = bpf_program__attach(prog); + err = libbpf_get_error(link); + if (err) { + fprintf(stderr, + "ERROR: bpf_program__attach failed: %d\n", + err); + goto out; + } + + if (over_high_ms) { + map = bpf_object__find_map_by_name(obj, "low_mcg_ops"); + if (!map) { + fprintf(stderr, + "ERROR: Failed to find low_mcg_ops map\n"); + err = -ESRCH; + goto out; + } + LIBBPF_OPTS_RESET(opts, + .flags = opts_flags, + .relative_fd = low_cgroup_fd, + ); + link_low = bpf_map__attach_struct_ops_opts(map, &opts); + if (!link_low) { + fprintf(stderr, + "Failed to attach struct ops low_mcg_ops: %d\n", + errno); + err = -errno; + goto out; + } + } + + if (use_below_low || use_below_min) { + map = bpf_object__find_map_by_name(obj, "high_mcg_ops"); + if (!map) { + fprintf(stderr, + "ERROR: Failed to find high_mcg_ops map\n"); + err = -ESRCH; + goto out; + } + LIBBPF_OPTS_RESET(opts, + .flags = opts_flags, + .relative_fd = high_cgroup_fd, + ); + link_high = bpf_map__attach_struct_ops_opts(map, &opts); + if (!link_high) { + fprintf(stderr, + "Failed to attach struct ops high_mcg_ops: %d\n", + errno); + err = -errno; + goto out; + } + } + + printf("Successfully attached!\n"); + + signal(SIGINT, sig_handler); + signal(SIGTERM, sig_handler); + + while (!exiting) + pause(); + + printf("Exiting...\n"); + +out: + bpf_link__destroy(link); + bpf_link__destroy(link_low); + bpf_link__destroy(link_high); + bpf_object__close(obj); + close(low_cgroup_fd); + close(high_cgroup_fd); + return err; +} -- 2.43.0
