diff options
Diffstat (limited to 'samples')
| -rw-r--r-- | samples/bpf/Makefile | 4 | ||||
| -rw-r--r-- | samples/bpf/lathist_kern.c | 99 | ||||
| -rw-r--r-- | samples/bpf/lathist_user.c | 103 |
3 files changed, 206 insertions, 0 deletions
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 46c6a8c..4450fed 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -12,6 +12,7 @@ hostprogs-y += tracex2 hostprogs-y += tracex3 hostprogs-y += tracex4 hostprogs-y += tracex5 +hostprogs-y += lathist test_verifier-objs := test_verifier.o libbpf.o test_maps-objs := test_maps.o libbpf.o @@ -24,6 +25,7 @@ tracex2-objs := bpf_load.o libbpf.o tracex2_user.o tracex3-objs := bpf_load.o libbpf.o tracex3_user.o tracex4-objs := bpf_load.o libbpf.o tracex4_user.o tracex5-objs := bpf_load.o libbpf.o tracex5_user.o +lathist-objs := bpf_load.o libbpf.o lathist_user.o # Tell kbuild to always build the programs always := $(hostprogs-y) @@ -36,6 +38,7 @@ always += tracex3_kern.o always += tracex4_kern.o always += tracex5_kern.o always += tcbpf1_kern.o +always += lathist_kern.o HOSTCFLAGS += -I$(objtree)/usr/include @@ -48,6 +51,7 @@ HOSTLOADLIBES_tracex2 += -lelf HOSTLOADLIBES_tracex3 += -lelf HOSTLOADLIBES_tracex4 += -lelf -lrt HOSTLOADLIBES_tracex5 += -lelf +HOSTLOADLIBES_lathist += -lelf # point this to your LLVM backend with bpf support LLC=$(srctree)/tools/bpf/llvm/bld/Debug+Asserts/bin/llc diff --git a/samples/bpf/lathist_kern.c b/samples/bpf/lathist_kern.c new file mode 100644 index 0000000..18fa088 --- /dev/null +++ b/samples/bpf/lathist_kern.c @@ -0,0 +1,99 @@ +/* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com + * Copyright (c) 2015 BMW Car IT GmbH + * + * 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 <linux/version.h> +#include <linux/ptrace.h> +#include <uapi/linux/bpf.h> +#include "bpf_helpers.h" + +#define MAX_ENTRIES 20 +#define MAX_CPU 4 + +/* We need to stick to static allocated memory (an array instead of + * hash table) because managing dynamic memory from the + * trace_preempt_[on|off] tracepoints hooks is not supported. + */ + +struct bpf_map_def SEC("maps") my_map = { + .type = BPF_MAP_TYPE_ARRAY, + .key_size = sizeof(int), + .value_size = sizeof(u64), + .max_entries = MAX_CPU, +}; + +SEC("kprobe/trace_preempt_off") +int bpf_prog1(struct pt_regs *ctx) +{ + int cpu = bpf_get_smp_processor_id(); + u64 *ts = bpf_map_lookup_elem(&my_map, &cpu); + + if (ts) + *ts = bpf_ktime_get_ns(); + + return 0; +} + +static unsigned int log2(unsigned int v) +{ + unsigned int r; + unsigned int shift; + + r = (v > 0xFFFF) << 4; v >>= r; + shift = (v > 0xFF) << 3; v >>= shift; r |= shift; + shift = (v > 0xF) << 2; v >>= shift; r |= shift; + shift = (v > 0x3) << 1; v >>= shift; r |= shift; + r |= (v >> 1); + + return r; +} + +static unsigned int log2l(unsigned long v) +{ + unsigned int hi = v >> 32; + + if (hi) + return log2(hi) + 32; + else + return log2(v); +} + +struct bpf_map_def SEC("maps") my_lat = { + .type = BPF_MAP_TYPE_ARRAY, + .key_size = sizeof(int), + .value_size = sizeof(long), + .max_entries = MAX_CPU * MAX_ENTRIES, +}; + +SEC("kprobe/trace_preempt_on") +int bpf_prog2(struct pt_regs *ctx) +{ + u64 *ts, cur_ts, delta; + int key, cpu; + long *val; + + cpu = bpf_get_smp_processor_id(); + ts = bpf_map_lookup_elem(&my_map, &cpu); + if (!ts) + return 0; + + cur_ts = bpf_ktime_get_ns(); + delta = log2l(cur_ts - *ts); + + if (delta > MAX_ENTRIES - 1) + delta = MAX_ENTRIES - 1; + + key = cpu * MAX_ENTRIES + delta; + val = bpf_map_lookup_elem(&my_lat, &key); + if (val) + __sync_fetch_and_add((long *)val, 1); + + return 0; + +} + +char _license[] SEC("license") = "GPL"; +u32 _version SEC("version") = LINUX_VERSION_CODE; diff --git a/samples/bpf/lathist_user.c b/samples/bpf/lathist_user.c new file mode 100644 index 0000000..65da8c1 --- /dev/null +++ b/samples/bpf/lathist_user.c @@ -0,0 +1,103 @@ +/* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com + * Copyright (c) 2015 BMW Car IT GmbH + * + * 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 <stdio.h> +#include <unistd.h> +#include <stdlib.h> +#include <signal.h> +#include <linux/bpf.h> +#include "libbpf.h" +#include "bpf_load.h" + +#define MAX_ENTRIES 20 +#define MAX_CPU 4 +#define MAX_STARS 40 + +struct cpu_hist { + long data[MAX_ENTRIES]; + long max; +}; + +static struct cpu_hist cpu_hist[MAX_CPU]; + +static void stars(char *str, long val, long max, int width) +{ + int i; + + for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++) + str[i] = '*'; + if (val > max) + str[i - 1] = '+'; + str[i] = '\0'; +} + +static void print_hist(void) +{ + char starstr[MAX_STARS]; + struct cpu_hist *hist; + int i, j; + + /* clear screen */ + printf("\033[2J"); + + for (j = 0; j < MAX_CPU; j++) { + hist = &cpu_hist[j]; + + /* ignore CPUs without data (maybe offline?) */ + if (hist->max == 0) + continue; + + printf("CPU %d\n", j); + printf(" latency : count distribution\n"); + for (i = 1; i <= MAX_ENTRIES; i++) { + stars(starstr, hist->data[i - 1], hist->max, MAX_STARS); + printf("%8ld -> %-8ld : %-8ld |%-*s|\n", + (1l << i) >> 1, (1l << i) - 1, + hist->data[i - 1], MAX_STARS, starstr); + } + } +} + +static void get_data(int fd) +{ + long key, value; + int c, i; + + for (i = 0; i < MAX_CPU; i++) + cpu_hist[i].max = 0; + + for (c = 0; c < MAX_CPU; c++) { + for (i = 0; i < MAX_ENTRIES; i++) { + key = c * MAX_ENTRIES + i; + bpf_lookup_elem(fd, &key, &value); + + cpu_hist[c].data[i] = value; + if (value > cpu_hist[c].max) + cpu_hist[c].max = value; + } + } +} + +int main(int argc, char **argv) +{ + char filename[256]; + + snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]); + + if (load_bpf_file(filename)) { + printf("%s", bpf_log_buf); + return 1; + } + + while (1) { + get_data(map_fd[1]); + print_hist(); + sleep(5); + } + + return 0; +} |
