diff options
Diffstat (limited to 'tools/perf/util/bpf_skel/func_latency.bpf.c')
| -rw-r--r-- | tools/perf/util/bpf_skel/func_latency.bpf.c | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/tools/perf/util/bpf_skel/func_latency.bpf.c b/tools/perf/util/bpf_skel/func_latency.bpf.c new file mode 100644 index 000000000000..621e2022c8bc --- /dev/null +++ b/tools/perf/util/bpf_skel/func_latency.bpf.c @@ -0,0 +1,199 @@ +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +// Copyright (c) 2021 Google +#include "vmlinux.h" +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +// This should be in sync with "util/ftrace.h" +#define NUM_BUCKET 22 + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(key_size, sizeof(__u64)); + __uint(value_size, sizeof(__u64)); + __uint(max_entries, 10000); +} functime 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"); + +struct { + __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); + __uint(key_size, sizeof(__u32)); + __uint(value_size, sizeof(__u64)); + __uint(max_entries, NUM_BUCKET); +} latency SEC(".maps"); + + +int enabled = 0; + +// stats +__s64 total; +__s64 count; +__s64 max; +__s64 min; + +const volatile int has_cpu = 0; +const volatile int has_task = 0; +const volatile int use_nsec = 0; +const volatile unsigned int bucket_range; +const volatile unsigned int min_latency; +const volatile unsigned int max_latency; +const volatile unsigned int bucket_num = NUM_BUCKET; + +static bool 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 false; + } + + if (has_task) { + __u32 pid = bpf_get_current_pid_tgid(); + __u8 *ok; + + ok = bpf_map_lookup_elem(&task_filter, &pid); + if (!ok) + return false; + } + return true; +} + +static void update_latency(__s64 delta) +{ + __u64 val = delta; + __u32 key = 0; + __u64 *hist; + __u64 cmp_base = use_nsec ? 1 : 1000; + + if (delta < 0) + return; + + if (bucket_range != 0) { + val = delta / cmp_base; + + if (min_latency > 0) { + if (val > min_latency) + val -= min_latency; + else + goto do_lookup; + } + + // Less than 1 unit (ms or ns), or, in the future, + // than the min latency desired. + if (val > 0) { // 1st entry: [ 1 unit .. bucket_range units ) + key = val / bucket_range + 1; + if (key >= bucket_num) + key = bucket_num - 1; + } + + goto do_lookup; + } + // calculate index using delta + for (key = 0; key < (bucket_num - 1); key++) { + if (delta < (cmp_base << key)) + break; + } + +do_lookup: + hist = bpf_map_lookup_elem(&latency, &key); + if (!hist) + return; + + __sync_fetch_and_add(hist, 1); + + __sync_fetch_and_add(&total, delta); // always in nsec + __sync_fetch_and_add(&count, 1); + + if (delta > max) + max = delta; + if (delta < min) + min = delta; +} + +SEC("kprobe/func") +int BPF_PROG(func_begin) +{ + __u64 key, now; + + if (!enabled || !can_record()) + return 0; + + key = bpf_get_current_pid_tgid(); + now = bpf_ktime_get_ns(); + + // overwrite timestamp for nested functions + bpf_map_update_elem(&functime, &key, &now, BPF_ANY); + return 0; +} + +SEC("kretprobe/func") +int BPF_PROG(func_end) +{ + __u64 tid; + __u64 *start; + + if (!enabled) + return 0; + + tid = bpf_get_current_pid_tgid(); + + start = bpf_map_lookup_elem(&functime, &tid); + if (start) { + update_latency(bpf_ktime_get_ns() - *start); + bpf_map_delete_elem(&functime, &tid); + } + + return 0; +} + +SEC("raw_tp") +int BPF_PROG(event_begin) +{ + __u64 key, now; + + if (!enabled || !can_record()) + return 0; + + key = bpf_get_current_pid_tgid(); + now = bpf_ktime_get_ns(); + + // overwrite timestamp for nested events + bpf_map_update_elem(&functime, &key, &now, BPF_ANY); + return 0; +} + +SEC("raw_tp") +int BPF_PROG(event_end) +{ + __u64 tid; + __u64 *start; + + if (!enabled) + return 0; + + tid = bpf_get_current_pid_tgid(); + + start = bpf_map_lookup_elem(&functime, &tid); + if (start) { + update_latency(bpf_ktime_get_ns() - *start); + bpf_map_delete_elem(&functime, &tid); + } + + return 0; +} |