Fill a memcg's TCP receive buffers from softirq while its only task sleeps, so the memcg goes over memory.high and high_work reclaims.
test_memcg_high_work checks that the memcg's cpu.stat and memory.pressure grow, which only happens if that reclaim is charged to the memcg. test_memcg_high_work_cpu_max also runs a CPU hog in the memcg under a cpu.max limit. The reclaim time should come out of the memcg's quota, so the hog should get less CPU while high_work is busy. Both need swap, so the anon memory can be reclaimed. Signed-off-by: Shakeel Butt <[email protected]> --- .../selftests/cgroup/test_memcontrol.c | 332 ++++++++++++++++++ 1 file changed, 332 insertions(+) diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c index 0ed82347044e..00802804c0d9 100644 --- a/tools/testing/selftests/cgroup/test_memcontrol.c +++ b/tools/testing/selftests/cgroup/test_memcontrol.c @@ -18,6 +18,7 @@ #include <netdb.h> #include <errno.h> #include <sys/mman.h> +#include <time.h> #include "kselftest.h" #include "cgroup_util.h" @@ -1474,6 +1475,335 @@ static int test_memcg_sock(const char *root) return ret; } +#define HIGH_WORK_NCONN 16 + +struct high_work_args { + int ctl[2]; +}; + +/* + * Fill some anon memory, accept HIGH_WORK_NCONN connections, then sleep + * without ever reading, so all received data stays charged to the memcg. + */ +static int high_work_receiver(const char *cgroup, void *arg) +{ + struct high_work_args *args = arg; + struct sockaddr_in sa = { .sin_family = AF_INET }; + socklen_t len = sizeof(sa); + int sk, i, rcvbuf = MB(8); + unsigned long long x = 1, *p; + size_t size = MB(256); + + close(args->ctl[0]); + + /* Hard to compress, so reclaiming it to swap takes real work. */ + p = mmap(NULL, size, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (p == MAP_FAILED) + return -1; + for (size_t j = 0; j < size / sizeof(*p); j++) { + x = x * 6364136223846793005ULL + 1442695040888963407ULL; + p[j] = x; + } + + sk = socket(AF_INET, SOCK_STREAM, 0); + if (sk < 0) + return -1; + if (setsockopt(sk, SOL_SOCKET, SO_RCVBUFFORCE, &rcvbuf, sizeof(rcvbuf))) + return -1; + sa.sin_addr.s_addr = htonl(INADDR_LOOPBACK); + if (bind(sk, (struct sockaddr *)&sa, len) || listen(sk, HIGH_WORK_NCONN)) + return -1; + if (getsockname(sk, (struct sockaddr *)&sa, &len)) + return -1; + if (write(args->ctl[1], &sa.sin_port, sizeof(sa.sin_port)) != + sizeof(sa.sin_port)) + return -1; + + for (i = 0; i < HIGH_WORK_NCONN; i++) + if (accept(sk, NULL, NULL) < 0) + return -1; + if (write(args->ctl[1], "A", 1) != 1) + return -1; + + for (;;) + pause(); + return 0; +} + +static long psi_some_total(const char *cgroup, const char *control) +{ + char buf[BUF_SIZE]; + long total; + + if (cg_read(cgroup, control, buf, sizeof(buf))) + return -1; + if (sscanf(buf, "some avg10=%*f avg60=%*f avg300=%*f total=%ld", + &total) != 1) + return -1; + return total; +} + +/* + * Socket memory charged from softirq can push a memcg over memory.high. + * The reclaim then runs from high_work on a kworker. The memcg's only task + * sleeps the whole time here, so its cpu.stat and memory.pressure only move + * if that reclaim is charged to the memcg. + */ +static int test_memcg_high_work(const char *root) +{ + int ret = KSFT_FAIL, pid = -1, i, sk[HIGH_WORK_NCONN]; + long usage, high, some, current, sent = 0; + struct high_work_args args; + char *memcg, *buf = NULL, c; + in_port_t port; + time_t last; + + for (i = 0; i < HIGH_WORK_NCONN; i++) + sk[i] = -1; + + if (!is_swap_enabled()) + return KSFT_SKIP; + + memcg = cg_name(root, "memcg_test"); + if (!memcg) + goto cleanup; + if (cg_create(memcg)) + goto cleanup; + if (pipe(args.ctl)) + goto cleanup; + + pid = cg_run_nowait(memcg, high_work_receiver, &args); + if (pid < 0) + goto cleanup; + close(args.ctl[1]); + if (read(args.ctl[0], &port, sizeof(port)) != sizeof(port)) + goto cleanup; + + for (i = 0; i < HIGH_WORK_NCONN; i++) { + struct sockaddr_in sa = { .sin_family = AF_INET, .sin_port = port }; + + sa.sin_addr.s_addr = htonl(INADDR_LOOPBACK); + sk[i] = socket(AF_INET, SOCK_STREAM, 0); + if (sk[i] < 0 || connect(sk[i], (struct sockaddr *)&sa, sizeof(sa))) + goto cleanup; + } + if (read(args.ctl[0], &c, 1) != 1) + goto cleanup; + + /* Just above the current usage, so this write does not reclaim. */ + current = cg_read_long(memcg, "memory.current"); + if (current < 0 || cg_write_numeric(memcg, "memory.high", current + MB(2))) + goto cleanup; + + usage = cg_read_key_long(memcg, "cpu.stat", "usage_usec "); + high = cg_read_key_long(memcg, "memory.events", "high "); + some = psi_some_total(memcg, "memory.pressure"); + + /* Fill all sockets until they stop taking data. */ + buf = calloc(1, MB(1)); + if (!buf) + goto cleanup; + last = time(NULL); + while (time(NULL) - last < 2) { + for (i = 0; i < HIGH_WORK_NCONN; i++) { + long n = send(sk[i], buf, MB(1), MSG_DONTWAIT); + + if (n > 0) { + sent += n; + last = time(NULL); + } + } + } + sleep(2); + + if (cg_read_key_long(memcg, "memory.events", "high ") <= high) { + ksft_print_msg("high_work did not run, sent %ld bytes\n", sent); + goto cleanup; + } + if (cg_read_key_long(memcg, "cpu.stat", "usage_usec ") <= usage) { + ksft_print_msg("high_work CPU time not charged to the memcg\n"); + goto cleanup; + } + if (some >= 0 && psi_some_total(memcg, "memory.pressure") <= some) { + ksft_print_msg("high_work stall not in memcg memory.pressure\n"); + goto cleanup; + } + + ret = KSFT_PASS; + +cleanup: + for (i = 0; i < HIGH_WORK_NCONN; i++) + if (sk[i] >= 0) + close(sk[i]); + if (pid > 0) { + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + } + free(buf); + cg_destroy(memcg); + free(memcg); + + return ret; +} + +static int high_work_spinner(const char *cgroup, void *arg) +{ + for (;;) + ; + return 0; +} + +/* CPU time @pid has used so far, in microseconds. */ +static long task_cpu_usec(int pid) +{ + unsigned long long ns; + char buf[128]; + + if (proc_read_text(pid, false, "schedstat", buf, sizeof(buf)) <= 0 || + sscanf(buf, "%llu", &ns) != 1) + return -1; + return ns / 1000; +} + +static long now_usec(void) +{ + struct timespec ts; + + clock_gettime(CLOCK_MONOTONIC, &ts); + return ts.tv_sec * 1000000L + ts.tv_nsec / 1000; +} + +/* + * The setup of test_memcg_high_work, plus a CPU hog in the memcg and a + * cpu.max limit. The reclaim that high_work does for the memcg should come + * out of the memcg's CPU quota, so the hog should get less CPU while + * high_work is busy than it gets otherwise. + */ +static int test_memcg_high_work_cpu_max(const char *root) +{ + int ret = KSFT_FAIL, pid = -1, hog = -1, i, sk[HIGH_WORK_NCONN]; + long current, h0, h1, h2, t0, t1, t2, u1, u2, reclaim, lost; + bool cpu_enabled = false; + struct high_work_args args; + char *memcg = NULL, *buf = NULL, c; + in_port_t port; + time_t last; + + for (i = 0; i < HIGH_WORK_NCONN; i++) + sk[i] = -1; + + if (!is_swap_enabled()) + return KSFT_SKIP; + if (cg_read_strstr(root, "cgroup.controllers", "cpu")) + return KSFT_SKIP; + if (cg_read_strstr(root, "cgroup.subtree_control", "cpu")) { + if (cg_write(root, "cgroup.subtree_control", "+cpu")) + return KSFT_SKIP; + cpu_enabled = true; + } + + memcg = cg_name(root, "memcg_test"); + if (!memcg || cg_create(memcg)) + goto cleanup; + /* 20% of a CPU, in short periods so the numbers come out smooth. */ + if (cg_write(memcg, "cpu.max", "2000 10000")) + goto cleanup; + if (pipe(args.ctl)) + goto cleanup; + + pid = cg_run_nowait(memcg, high_work_receiver, &args); + if (pid < 0) + goto cleanup; + close(args.ctl[1]); + if (read(args.ctl[0], &port, sizeof(port)) != sizeof(port)) + goto cleanup; + + for (i = 0; i < HIGH_WORK_NCONN; i++) { + struct sockaddr_in sa = { .sin_family = AF_INET, .sin_port = port }; + + sa.sin_addr.s_addr = htonl(INADDR_LOOPBACK); + sk[i] = socket(AF_INET, SOCK_STREAM, 0); + if (sk[i] < 0 || connect(sk[i], (struct sockaddr *)&sa, sizeof(sa))) + goto cleanup; + } + if (read(args.ctl[0], &c, 1) != 1) + goto cleanup; + + hog = cg_run_nowait(memcg, high_work_spinner, NULL); + if (hog < 0) + goto cleanup; + + current = cg_read_long(memcg, "memory.current"); + if (current < 0 || cg_write_numeric(memcg, "memory.high", current + MB(2))) + goto cleanup; + + /* How much CPU the hog gets without high_work. */ + sleep(1); + h0 = task_cpu_usec(hog); + t0 = now_usec(); + sleep(3); + h1 = task_cpu_usec(hog); + t1 = now_usec(); + u1 = cg_read_key_long(memcg, "cpu.stat", "usage_usec "); + + /* Fill the sockets slowly, so high_work runs many times. */ + buf = calloc(1, 64 << 10); + if (!buf) + goto cleanup; + last = time(NULL); + while (time(NULL) - last < 2) { + for (i = 0; i < HIGH_WORK_NCONN; i++) + if (send(sk[i], buf, 64 << 10, MSG_DONTWAIT) > 0) + last = time(NULL); + usleep(15000); + } + h2 = task_cpu_usec(hog); + t2 = now_usec(); + u2 = cg_read_key_long(memcg, "cpu.stat", "usage_usec "); + + if (h0 < 0 || h1 <= h0 || h2 < 0 || u1 < 0 || u2 < 0) + goto cleanup; + + /* The receiver sleeps, so the rest of the memcg's time is high_work. */ + reclaim = (u2 - u1) - (h2 - h1); + lost = (h1 - h0) * (t2 - t1) / (t1 - t0) - (h2 - h1); + if (reclaim < 30000) { + ksft_print_msg("high_work used only %ld us, too little to test\n", + reclaim); + ret = KSFT_SKIP; + goto cleanup; + } + if (lost < reclaim / 3) { + ksft_print_msg("hog lost %ld us, high_work used %ld us\n", + lost, reclaim); + goto cleanup; + } + + ret = KSFT_PASS; + +cleanup: + for (i = 0; i < HIGH_WORK_NCONN; i++) + if (sk[i] >= 0) + close(sk[i]); + if (hog > 0) { + kill(hog, SIGKILL); + waitpid(hog, NULL, 0); + } + if (pid > 0) { + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + } + free(buf); + if (memcg) + cg_destroy(memcg); + free(memcg); + if (cpu_enabled) + cg_write(root, "cgroup.subtree_control", "-cpu"); + + return ret; +} + /* * This test disables swapping and tries to allocate anonymous memory * up to OOM with memory.group.oom set. Then it checks that all @@ -1780,6 +2110,8 @@ struct memcg_test { T(test_memcg_oom_events), T(test_memcg_swap_max_peak), T(test_memcg_sock), + T(test_memcg_high_work), + T(test_memcg_high_work_cpu_max), T(test_memcg_oom_group_leaf_events), T(test_memcg_oom_group_parent_events), T(test_memcg_oom_group_score_events), -- 2.53.0-Meta
