diff options
Diffstat (limited to 'tools/perf/util/bpf_skel/lock_contention.bpf.c')
| -rw-r--r-- | tools/perf/util/bpf_skel/lock_contention.bpf.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c new file mode 100644 index 000000000000..9e8b94eb6320 --- /dev/null +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c @@ -0,0 +1,175 @@ +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +// Copyright (c) 2022 Google +#include "vmlinux.h" +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> +#include <bpf/bpf_core_read.h> + +/* maximum stack trace depth */ +#define MAX_STACKS 8 + +/* default buffer size */ +#define MAX_ENTRIES 10240 + +struct contention_key { + __s32 stack_id; +}; + +struct contention_data { + __u64 total_time; + __u64 min_time; + __u64 max_time; + __u32 count; + __u32 flags; +}; + +struct tstamp_data { + __u64 timestamp; + __u64 lock; + __u32 flags; + __s32 stack_id; +}; + +/* callstack storage */ +struct { + __uint(type, BPF_MAP_TYPE_STACK_TRACE); + __uint(key_size, sizeof(__u32)); + __uint(value_size, MAX_STACKS * sizeof(__u64)); + __uint(max_entries, MAX_ENTRIES); +} stacks SEC(".maps"); + +/* maintain timestamp at the beginning of contention */ +struct { + __uint(type, BPF_MAP_TYPE_TASK_STORAGE); + __uint(map_flags, BPF_F_NO_PREALLOC); + __type(key, int); + __type(value, struct tstamp_data); +} tstamp SEC(".maps"); + +/* actual lock contention statistics */ +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(key_size, sizeof(struct contention_key)); + __uint(value_size, sizeof(struct contention_data)); + __uint(max_entries, MAX_ENTRIES); +} lock_stat SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(key_size, sizeof(__u32)); + __uint(value_size, sizeof(__u8)); + __uint(max_entries, 1); +} cpu_filter SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(key_size, sizeof(__u32)); + __uint(value_size, sizeof(__u8)); + __uint(max_entries, 1); +} task_filter SEC(".maps"); + +/* control flags */ +int enabled; +int has_cpu; +int has_task; + +/* error stat */ +unsigned long lost; + +static inline int can_record(void) +{ + if (has_cpu) { + __u32 cpu = bpf_get_smp_processor_id(); + __u8 *ok; + + ok = bpf_map_lookup_elem(&cpu_filter, &cpu); + if (!ok) + return 0; + } + + if (has_task) { + __u8 *ok; + __u32 pid = bpf_get_current_pid_tgid(); + + ok = bpf_map_lookup_elem(&task_filter, &pid); + if (!ok) + return 0; + } + + return 1; +} + +SEC("tp_btf/contention_begin") +int contention_begin(u64 *ctx) +{ + struct task_struct *curr; + struct tstamp_data *pelem; + + if (!enabled || !can_record()) + return 0; + + curr = bpf_get_current_task_btf(); + pelem = bpf_task_storage_get(&tstamp, curr, NULL, + BPF_LOCAL_STORAGE_GET_F_CREATE); + if (!pelem || pelem->lock) + return 0; + + pelem->timestamp = bpf_ktime_get_ns(); + pelem->lock = (__u64)ctx[0]; + pelem->flags = (__u32)ctx[1]; + pelem->stack_id = bpf_get_stackid(ctx, &stacks, BPF_F_FAST_STACK_CMP); + + if (pelem->stack_id < 0) + lost++; + return 0; +} + +SEC("tp_btf/contention_end") +int contention_end(u64 *ctx) +{ + struct task_struct *curr; + struct tstamp_data *pelem; + struct contention_key key; + struct contention_data *data; + __u64 duration; + + if (!enabled) + return 0; + + curr = bpf_get_current_task_btf(); + pelem = bpf_task_storage_get(&tstamp, curr, NULL, 0); + if (!pelem || pelem->lock != ctx[0]) + return 0; + + duration = bpf_ktime_get_ns() - pelem->timestamp; + + key.stack_id = pelem->stack_id; + data = bpf_map_lookup_elem(&lock_stat, &key); + if (!data) { + struct contention_data first = { + .total_time = duration, + .max_time = duration, + .min_time = duration, + .count = 1, + .flags = pelem->flags, + }; + + bpf_map_update_elem(&lock_stat, &key, &first, BPF_NOEXIST); + pelem->lock = 0; + return 0; + } + + __sync_fetch_and_add(&data->total_time, duration); + __sync_fetch_and_add(&data->count, 1); + + /* FIXME: need atomic operations */ + if (data->max_time < duration) + data->max_time = duration; + if (data->min_time > duration) + data->min_time = duration; + + pelem->lock = 0; + return 0; +} + +char LICENSE[] SEC("license") = "Dual BSD/GPL"; |