From 39111695b1b88a21e81983a38786d877e770da81 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Tue, 20 Oct 2015 20:02:35 -0700 Subject: samples: bpf: add bpf_perf_event_output example Performance test and example of bpf_perf_event_output(). kprobe is attached to sys_write() and trivial bpf program streams pid+cookie into userspace via PERF_COUNT_SW_BPF_OUTPUT event. Usage: $ sudo ./bld_x64/samples/bpf/trace_output recv 2968913 events per sec Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- samples/bpf/trace_output_user.c | 196 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 196 insertions(+) create mode 100644 samples/bpf/trace_output_user.c (limited to 'samples/bpf/trace_output_user.c') diff --git a/samples/bpf/trace_output_user.c b/samples/bpf/trace_output_user.c new file mode 100644 index 000000000000..661a7d052f2c --- /dev/null +++ b/samples/bpf/trace_output_user.c @@ -0,0 +1,196 @@ +/* This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "libbpf.h" +#include "bpf_load.h" + +static int pmu_fd; + +int page_size; +int page_cnt = 8; +volatile struct perf_event_mmap_page *header; + +typedef void (*print_fn)(void *data, int size); + +static int perf_event_mmap(int fd) +{ + void *base; + int mmap_size; + + page_size = getpagesize(); + mmap_size = page_size * (page_cnt + 1); + + base = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); + if (base == MAP_FAILED) { + printf("mmap err\n"); + return -1; + } + + header = base; + return 0; +} + +static int perf_event_poll(int fd) +{ + struct pollfd pfd = { .fd = fd, .events = POLLIN }; + + return poll(&pfd, 1, 1000); +} + +struct perf_event_sample { + struct perf_event_header header; + __u32 size; + char data[]; +}; + +void perf_event_read(print_fn fn) +{ + __u64 data_tail = header->data_tail; + __u64 data_head = header->data_head; + __u64 buffer_size = page_cnt * page_size; + void *base, *begin, *end; + char buf[256]; + + asm volatile("" ::: "memory"); /* in real code it should be smp_rmb() */ + if (data_head == data_tail) + return; + + base = ((char *)header) + page_size; + + begin = base + data_tail % buffer_size; + end = base + data_head % buffer_size; + + while (begin != end) { + struct perf_event_sample *e; + + e = begin; + if (begin + e->header.size > base + buffer_size) { + long len = base + buffer_size - begin; + + assert(len < e->header.size); + memcpy(buf, begin, len); + memcpy(buf + len, base, e->header.size - len); + e = (void *) buf; + begin = base + e->header.size - len; + } else if (begin + e->header.size == base + buffer_size) { + begin = base; + } else { + begin += e->header.size; + } + + if (e->header.type == PERF_RECORD_SAMPLE) { + fn(e->data, e->size); + } else if (e->header.type == PERF_RECORD_LOST) { + struct { + struct perf_event_header header; + __u64 id; + __u64 lost; + } *lost = (void *) e; + printf("lost %lld events\n", lost->lost); + } else { + printf("unknown event type=%d size=%d\n", + e->header.type, e->header.size); + } + } + + __sync_synchronize(); /* smp_mb() */ + header->data_tail = data_head; +} + +static __u64 time_get_ns(void) +{ + struct timespec ts; + + clock_gettime(CLOCK_MONOTONIC, &ts); + return ts.tv_sec * 1000000000ull + ts.tv_nsec; +} + +static __u64 start_time; + +#define MAX_CNT 100000ll + +static void print_bpf_output(void *data, int size) +{ + static __u64 cnt; + struct { + __u64 pid; + __u64 cookie; + } *e = data; + + if (e->cookie != 0x12345678) { + printf("BUG pid %llx cookie %llx sized %d\n", + e->pid, e->cookie, size); + kill(0, SIGINT); + } + + cnt++; + + if (cnt == MAX_CNT) { + printf("recv %lld events per sec\n", + MAX_CNT * 1000000000ll / (time_get_ns() - start_time)); + kill(0, SIGINT); + } +} + +static void test_bpf_perf_event(void) +{ + struct perf_event_attr attr = { + .sample_type = PERF_SAMPLE_RAW, + .type = PERF_TYPE_SOFTWARE, + .config = PERF_COUNT_SW_BPF_OUTPUT, + }; + int key = 0; + + pmu_fd = perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0); + + assert(pmu_fd >= 0); + assert(bpf_update_elem(map_fd[0], &key, &pmu_fd, BPF_ANY) == 0); + ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0); +} + +int main(int argc, char **argv) +{ + char filename[256]; + FILE *f; + + snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]); + + if (load_bpf_file(filename)) { + printf("%s", bpf_log_buf); + return 1; + } + + test_bpf_perf_event(); + + if (perf_event_mmap(pmu_fd) < 0) + return 1; + + f = popen("taskset 1 dd if=/dev/zero of=/dev/null", "r"); + (void) f; + + start_time = time_get_ns(); + for (;;) { + perf_event_poll(pmu_fd); + perf_event_read(print_bpf_output); + } + + return 0; +} -- cgit v1.2.3-59-g8ed1b