diff options
Diffstat (limited to 'tools/testing/selftests/bpf/test_kmods/bpf_test_rqspinlock.c')
| -rw-r--r-- | tools/testing/selftests/bpf/test_kmods/bpf_test_rqspinlock.c | 393 |
1 files changed, 393 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_test_rqspinlock.c b/tools/testing/selftests/bpf/test_kmods/bpf_test_rqspinlock.c new file mode 100644 index 000000000000..7b4ae5e81d32 --- /dev/null +++ b/tools/testing/selftests/bpf/test_kmods/bpf_test_rqspinlock.c @@ -0,0 +1,393 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */ +#include <linux/sched.h> +#include <linux/smp.h> +#include <linux/delay.h> +#include <linux/module.h> +#include <linux/prandom.h> +#include <linux/ktime.h> +#include <asm/rqspinlock.h> +#include <linux/perf_event.h> +#include <linux/kthread.h> +#include <linux/atomic.h> +#include <linux/slab.h> + +static struct perf_event_attr hw_attr = { + .type = PERF_TYPE_HARDWARE, + .config = PERF_COUNT_HW_CPU_CYCLES, + .size = sizeof(struct perf_event_attr), + .pinned = 1, + .disabled = 1, + .sample_period = 100000, +}; + +static rqspinlock_t lock_a; +static rqspinlock_t lock_b; +static rqspinlock_t lock_c; + +#define RQSL_SLOW_THRESHOLD_MS 10 +static const unsigned int rqsl_hist_ms[] = { + 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, + 12, 14, 16, 18, 20, 25, 30, 40, 50, 75, + 100, 150, 200, 250, 1000, +}; +#define RQSL_NR_HIST_BUCKETS ARRAY_SIZE(rqsl_hist_ms) + +enum rqsl_context { + RQSL_CTX_NORMAL = 0, + RQSL_CTX_NMI, + RQSL_CTX_MAX, +}; + +struct rqsl_cpu_hist { + atomic64_t hist[RQSL_CTX_MAX][RQSL_NR_HIST_BUCKETS]; + atomic64_t success[RQSL_CTX_MAX]; + atomic64_t failure[RQSL_CTX_MAX]; +}; + +static DEFINE_PER_CPU(struct rqsl_cpu_hist, rqsl_cpu_hists); + +enum rqsl_mode { + RQSL_MODE_AA = 0, + RQSL_MODE_ABBA, + RQSL_MODE_ABBCCA, +}; + +static int test_mode = RQSL_MODE_AA; +module_param(test_mode, int, 0644); +MODULE_PARM_DESC(test_mode, + "rqspinlock test mode: 0 = AA, 1 = ABBA, 2 = ABBCCA"); + +static int normal_delay = 20; +module_param(normal_delay, int, 0644); +MODULE_PARM_DESC(normal_delay, + "rqspinlock critical section length for normal context (20ms default)"); + +static int nmi_delay = 10; +module_param(nmi_delay, int, 0644); +MODULE_PARM_DESC(nmi_delay, + "rqspinlock critical section length for NMI context (10ms default)"); + +static struct perf_event **rqsl_evts; +static int rqsl_nevts; + +static struct task_struct **rqsl_threads; +static int rqsl_nthreads; +static atomic_t rqsl_ready_cpus = ATOMIC_INIT(0); + +static int pause = 0; + +static const char *rqsl_mode_names[] = { + [RQSL_MODE_AA] = "AA", + [RQSL_MODE_ABBA] = "ABBA", + [RQSL_MODE_ABBCCA] = "ABBCCA", +}; + +struct rqsl_lock_pair { + rqspinlock_t *worker_lock; + rqspinlock_t *nmi_lock; +}; + +static struct rqsl_lock_pair rqsl_get_lock_pair(int cpu) +{ + int mode = READ_ONCE(test_mode); + + switch (mode) { + default: + case RQSL_MODE_AA: + return (struct rqsl_lock_pair){ &lock_a, &lock_a }; + case RQSL_MODE_ABBA: + if (cpu & 1) + return (struct rqsl_lock_pair){ &lock_b, &lock_a }; + return (struct rqsl_lock_pair){ &lock_a, &lock_b }; + case RQSL_MODE_ABBCCA: + switch (cpu % 3) { + case 0: + return (struct rqsl_lock_pair){ &lock_a, &lock_b }; + case 1: + return (struct rqsl_lock_pair){ &lock_b, &lock_c }; + default: + return (struct rqsl_lock_pair){ &lock_c, &lock_a }; + } + } +} + +static u32 rqsl_hist_bucket_idx(u32 delta_ms) +{ + int i; + + for (i = 0; i < RQSL_NR_HIST_BUCKETS; i++) { + if (delta_ms <= rqsl_hist_ms[i]) + return i; + } + + return RQSL_NR_HIST_BUCKETS - 1; +} + +static void rqsl_record_lock_result(u64 delta_ns, enum rqsl_context ctx, int ret) +{ + struct rqsl_cpu_hist *hist = this_cpu_ptr(&rqsl_cpu_hists); + u32 delta_ms = DIV_ROUND_UP_ULL(delta_ns, NSEC_PER_MSEC); + u32 bucket = rqsl_hist_bucket_idx(delta_ms); + atomic64_t *buckets = hist->hist[ctx]; + + atomic64_inc(&buckets[bucket]); + if (!ret) + atomic64_inc(&hist->success[ctx]); + else + atomic64_inc(&hist->failure[ctx]); +} + +static int rqspinlock_worker_fn(void *arg) +{ + int cpu = smp_processor_id(); + unsigned long flags; + u64 start_ns; + int ret; + + if (cpu) { + atomic_inc(&rqsl_ready_cpus); + + while (!kthread_should_stop()) { + struct rqsl_lock_pair locks = rqsl_get_lock_pair(cpu); + rqspinlock_t *worker_lock = locks.worker_lock; + + if (READ_ONCE(pause)) { + msleep(1000); + continue; + } + start_ns = ktime_get_mono_fast_ns(); + ret = raw_res_spin_lock_irqsave(worker_lock, flags); + rqsl_record_lock_result(ktime_get_mono_fast_ns() - start_ns, + RQSL_CTX_NORMAL, ret); + mdelay(normal_delay); + if (!ret) + raw_res_spin_unlock_irqrestore(worker_lock, flags); + cpu_relax(); + } + return 0; + } + + while (!kthread_should_stop()) { + int expected = rqsl_nthreads > 0 ? rqsl_nthreads - 1 : 0; + int ready = atomic_read(&rqsl_ready_cpus); + + if (ready == expected && !READ_ONCE(pause)) { + for (int i = 0; i < rqsl_nevts; i++) + perf_event_enable(rqsl_evts[i]); + pr_err("Waiting 5 secs to pause the test\n"); + msleep(1000 * 5); + WRITE_ONCE(pause, 1); + pr_err("Paused the test\n"); + } else { + msleep(1000); + cpu_relax(); + } + } + return 0; +} + +static void nmi_cb(struct perf_event *event, struct perf_sample_data *data, + struct pt_regs *regs) +{ + struct rqsl_lock_pair locks; + int cpu = smp_processor_id(); + unsigned long flags; + u64 start_ns; + int ret; + + if (!cpu || READ_ONCE(pause)) + return; + + locks = rqsl_get_lock_pair(cpu); + start_ns = ktime_get_mono_fast_ns(); + ret = raw_res_spin_lock_irqsave(locks.nmi_lock, flags); + rqsl_record_lock_result(ktime_get_mono_fast_ns() - start_ns, + RQSL_CTX_NMI, ret); + + mdelay(nmi_delay); + + if (!ret) + raw_res_spin_unlock_irqrestore(locks.nmi_lock, flags); +} + +static void free_rqsl_threads(void) +{ + int i; + + if (rqsl_threads) { + for_each_online_cpu(i) { + if (rqsl_threads[i]) + kthread_stop(rqsl_threads[i]); + } + kfree(rqsl_threads); + } +} + +static void free_rqsl_evts(void) +{ + int i; + + if (rqsl_evts) { + for (i = 0; i < rqsl_nevts; i++) { + if (rqsl_evts[i]) + perf_event_release_kernel(rqsl_evts[i]); + } + kfree(rqsl_evts); + } +} + +static int bpf_test_rqspinlock_init(void) +{ + int i, ret; + int ncpus = num_online_cpus(); + + if (test_mode < RQSL_MODE_AA || test_mode > RQSL_MODE_ABBCCA) { + pr_err("Invalid mode %d\n", test_mode); + return -EINVAL; + } + + pr_err("Mode = %s\n", rqsl_mode_names[test_mode]); + + if (ncpus < test_mode + 2) + return -ENOTSUPP; + + raw_res_spin_lock_init(&lock_a); + raw_res_spin_lock_init(&lock_b); + raw_res_spin_lock_init(&lock_c); + + rqsl_evts = kcalloc(ncpus - 1, sizeof(*rqsl_evts), GFP_KERNEL); + if (!rqsl_evts) + return -ENOMEM; + rqsl_nevts = ncpus - 1; + + for (i = 1; i < ncpus; i++) { + struct perf_event *e; + + e = perf_event_create_kernel_counter(&hw_attr, i, NULL, nmi_cb, NULL); + if (IS_ERR(e)) { + ret = PTR_ERR(e); + goto err_perf_events; + } + rqsl_evts[i - 1] = e; + } + + rqsl_threads = kcalloc(ncpus, sizeof(*rqsl_threads), GFP_KERNEL); + if (!rqsl_threads) { + ret = -ENOMEM; + goto err_perf_events; + } + rqsl_nthreads = ncpus; + + for_each_online_cpu(i) { + struct task_struct *t; + + t = kthread_create(rqspinlock_worker_fn, NULL, "rqsl_w/%d", i); + if (IS_ERR(t)) { + ret = PTR_ERR(t); + goto err_threads_create; + } + kthread_bind(t, i); + rqsl_threads[i] = t; + wake_up_process(t); + } + return 0; + +err_threads_create: + free_rqsl_threads(); +err_perf_events: + free_rqsl_evts(); + return ret; +} + +module_init(bpf_test_rqspinlock_init); + +static void rqsl_print_histograms(void) +{ + int cpu, i; + + pr_err("rqspinlock acquisition latency histogram (ms):\n"); + + for_each_online_cpu(cpu) { + struct rqsl_cpu_hist *hist = per_cpu_ptr(&rqsl_cpu_hists, cpu); + u64 norm_counts[RQSL_NR_HIST_BUCKETS]; + u64 nmi_counts[RQSL_NR_HIST_BUCKETS]; + u64 total_counts[RQSL_NR_HIST_BUCKETS]; + u64 norm_success, nmi_success, success_total; + u64 norm_failure, nmi_failure, failure_total; + u64 norm_total = 0, nmi_total = 0, total = 0; + bool has_slow = false; + + for (i = 0; i < RQSL_NR_HIST_BUCKETS; i++) { + norm_counts[i] = atomic64_read(&hist->hist[RQSL_CTX_NORMAL][i]); + nmi_counts[i] = atomic64_read(&hist->hist[RQSL_CTX_NMI][i]); + total_counts[i] = norm_counts[i] + nmi_counts[i]; + norm_total += norm_counts[i]; + nmi_total += nmi_counts[i]; + total += total_counts[i]; + if (rqsl_hist_ms[i] > RQSL_SLOW_THRESHOLD_MS && + total_counts[i]) + has_slow = true; + } + + norm_success = atomic64_read(&hist->success[RQSL_CTX_NORMAL]); + nmi_success = atomic64_read(&hist->success[RQSL_CTX_NMI]); + norm_failure = atomic64_read(&hist->failure[RQSL_CTX_NORMAL]); + nmi_failure = atomic64_read(&hist->failure[RQSL_CTX_NMI]); + success_total = norm_success + nmi_success; + failure_total = norm_failure + nmi_failure; + + if (!total) + continue; + + if (!has_slow) { + pr_err(" cpu%d: total %llu (normal %llu, nmi %llu) | " + "success %llu (normal %llu, nmi %llu) | " + "failure %llu (normal %llu, nmi %llu), all within 0-%ums\n", + cpu, total, norm_total, nmi_total, + success_total, norm_success, nmi_success, + failure_total, norm_failure, nmi_failure, + RQSL_SLOW_THRESHOLD_MS); + continue; + } + + pr_err(" cpu%d: total %llu (normal %llu, nmi %llu) | " + "success %llu (normal %llu, nmi %llu) | " + "failure %llu (normal %llu, nmi %llu)\n", + cpu, total, norm_total, nmi_total, + success_total, norm_success, nmi_success, + failure_total, norm_failure, nmi_failure); + for (i = 0; i < RQSL_NR_HIST_BUCKETS; i++) { + unsigned int start_ms; + + if (!total_counts[i]) + continue; + + start_ms = i == 0 ? 0 : rqsl_hist_ms[i - 1] + 1; + if (i == RQSL_NR_HIST_BUCKETS - 1) { + pr_err(" >= %ums: total %llu (normal %llu, nmi %llu)\n", + start_ms, total_counts[i], + norm_counts[i], nmi_counts[i]); + } else { + pr_err(" %u-%ums: total %llu (normal %llu, nmi %llu)\n", + start_ms, rqsl_hist_ms[i], + total_counts[i], + norm_counts[i], nmi_counts[i]); + } + } + } +} + +static void bpf_test_rqspinlock_exit(void) +{ + WRITE_ONCE(pause, 1); + free_rqsl_threads(); + free_rqsl_evts(); + rqsl_print_histograms(); +} + +module_exit(bpf_test_rqspinlock_exit); + +MODULE_AUTHOR("Kumar Kartikeya Dwivedi"); +MODULE_DESCRIPTION("BPF rqspinlock stress test module"); +MODULE_LICENSE("GPL"); |