| Message ID | 20220418124834.829064-5-jolsa@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | bpf: Speed up symbol resolving in kprobe multi link | expand |
On Mon, Apr 18, 2022 at 5:49 AM Jiri Olsa <jolsa@kernel.org> wrote: > > Adding test that reads all functions from ftrace available_filter_functions > file and attach them all through kprobe_multi API. > > It also prints stats info with -v option, like on my setup: > > test_bench_attach: found 48712 functions > test_bench_attach: attached in 1.069s > test_bench_attach: detached in 0.373s > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- > .../bpf/prog_tests/kprobe_multi_test.c | 136 ++++++++++++++++++ > .../selftests/bpf/progs/kprobe_multi_empty.c | 12 ++ > 2 files changed, 148 insertions(+) > create mode 100644 tools/testing/selftests/bpf/progs/kprobe_multi_empty.c > > diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c > index b9876b55fc0c..05f0fab8af89 100644 > --- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c > +++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c > @@ -2,6 +2,9 @@ > #include <test_progs.h> > #include "kprobe_multi.skel.h" > #include "trace_helpers.h" > +#include "kprobe_multi_empty.skel.h" > +#include "bpf/libbpf_internal.h" > +#include "bpf/hashmap.h" > > static void kprobe_multi_test_run(struct kprobe_multi *skel, bool test_return) > { > @@ -301,6 +304,137 @@ static void test_attach_api_fails(void) > kprobe_multi__destroy(skel); > } > > +static inline __u64 get_time_ns(void) > +{ > + struct timespec t; > + > + clock_gettime(CLOCK_MONOTONIC, &t); > + return (__u64) t.tv_sec * 1000000000 + t.tv_nsec; > +} > + > +static size_t symbol_hash(const void *key, void *ctx __maybe_unused) > +{ > + return str_hash((const char *) key); > +} > + > +static bool symbol_equal(const void *key1, const void *key2, void *ctx __maybe_unused) > +{ > + return strcmp((const char *) key1, (const char *) key2) == 0; > +} > + > +#define DEBUGFS "/sys/kernel/debug/tracing/" > + > +static int get_syms(char ***symsp, size_t *cntp) > +{ > + size_t cap = 0, cnt = 0, i; > + char *name, **syms = NULL; > + struct hashmap *map; > + char buf[256]; > + FILE *f; > + int err; > + > + /* > + * The available_filter_functions contains many duplicates, > + * but other than that all symbols are usable in kprobe multi > + * interface. > + * Filtering out duplicates by using hashmap__add, which won't > + * add existing entry. > + */ > + f = fopen(DEBUGFS "available_filter_functions", "r"); nit: DEBUGFS "constant" just makes it harder to follow the code and doesn't add anything, please just use the full path here directly > + if (!f) > + return -EINVAL; > + > + map = hashmap__new(symbol_hash, symbol_equal, NULL); > + err = libbpf_get_error(map); hashmap__new() is an internal API, so please use IS_ERR() directly here. libbpf_get_error() should be used for public libbpf APIs, and preferably not in libbpf 1.0 mode > + if (err) > + goto error; > + > + while (fgets(buf, sizeof(buf), f)) { > + /* skip modules */ > + if (strchr(buf, '[')) > + continue; [...] > + attach_delta = (attach_end_ns - attach_start_ns) / 1000000000.0; > + detach_delta = (detach_end_ns - detach_start_ns) / 1000000000.0; > + > + fprintf(stderr, "%s: found %lu functions\n", __func__, cnt); > + fprintf(stderr, "%s: attached in %7.3lfs\n", __func__, attach_delta); > + fprintf(stderr, "%s: detached in %7.3lfs\n", __func__, detach_delta); why stderr? just do printf() and let test_progs handle output > + > +cleanup: > + kprobe_multi_empty__destroy(skel); > + if (syms) { > + for (i = 0; i < cnt; i++) > + free(syms[i]); > + free(syms); > + } > +} > + > void test_kprobe_multi_test(void) > { > if (!ASSERT_OK(load_kallsyms(), "load_kallsyms")) > @@ -320,4 +454,6 @@ void test_kprobe_multi_test(void) > test_attach_api_syms(); > if (test__start_subtest("attach_api_fails")) > test_attach_api_fails(); > + if (test__start_subtest("bench_attach")) > + test_bench_attach(); > } > diff --git a/tools/testing/selftests/bpf/progs/kprobe_multi_empty.c b/tools/testing/selftests/bpf/progs/kprobe_multi_empty.c > new file mode 100644 > index 000000000000..be9e3d891d46 > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/kprobe_multi_empty.c > @@ -0,0 +1,12 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#include <linux/bpf.h> > +#include <bpf/bpf_helpers.h> > +#include <bpf/bpf_tracing.h> > + > +char _license[] SEC("license") = "GPL"; > + > +SEC("kprobe.multi/*") use SEC("kprobe.multi") to make it clear that we are attaching it "manually"? > +int test_kprobe_empty(struct pt_regs *ctx) > +{ > + return 0; > +} > -- > 2.35.1 >
On Wed, Apr 20, 2022 at 02:56:53PM -0700, Andrii Nakryiko wrote: SNIP > > +#define DEBUGFS "/sys/kernel/debug/tracing/" > > + > > +static int get_syms(char ***symsp, size_t *cntp) > > +{ > > + size_t cap = 0, cnt = 0, i; > > + char *name, **syms = NULL; > > + struct hashmap *map; > > + char buf[256]; > > + FILE *f; > > + int err; > > + > > + /* > > + * The available_filter_functions contains many duplicates, > > + * but other than that all symbols are usable in kprobe multi > > + * interface. > > + * Filtering out duplicates by using hashmap__add, which won't > > + * add existing entry. > > + */ > > + f = fopen(DEBUGFS "available_filter_functions", "r"); > > nit: DEBUGFS "constant" just makes it harder to follow the code and > doesn't add anything, please just use the full path here directly there's another one DEBUGFS in trace_helpers.c, we could put it in trace_helpers.h > > > + if (!f) > > + return -EINVAL; > > + > > + map = hashmap__new(symbol_hash, symbol_equal, NULL); > > + err = libbpf_get_error(map); > > hashmap__new() is an internal API, so please use IS_ERR() directly > here. libbpf_get_error() should be used for public libbpf APIs, and > preferably not in libbpf 1.0 mode ok > > > + if (err) > > + goto error; > > + > > + while (fgets(buf, sizeof(buf), f)) { > > + /* skip modules */ > > + if (strchr(buf, '[')) > > + continue; > > [...] > > > + attach_delta = (attach_end_ns - attach_start_ns) / 1000000000.0; > > + detach_delta = (detach_end_ns - detach_start_ns) / 1000000000.0; > > + > > + fprintf(stderr, "%s: found %lu functions\n", __func__, cnt); > > + fprintf(stderr, "%s: attached in %7.3lfs\n", __func__, attach_delta); > > + fprintf(stderr, "%s: detached in %7.3lfs\n", __func__, detach_delta); > > > why stderr? just do printf() and let test_progs handle output ok > > > > + > > +cleanup: > > + kprobe_multi_empty__destroy(skel); > > + if (syms) { > > + for (i = 0; i < cnt; i++) > > + free(syms[i]); > > + free(syms); > > + } > > +} > > + > > void test_kprobe_multi_test(void) > > { > > if (!ASSERT_OK(load_kallsyms(), "load_kallsyms")) > > @@ -320,4 +454,6 @@ void test_kprobe_multi_test(void) > > test_attach_api_syms(); > > if (test__start_subtest("attach_api_fails")) > > test_attach_api_fails(); > > + if (test__start_subtest("bench_attach")) > > + test_bench_attach(); > > } > > diff --git a/tools/testing/selftests/bpf/progs/kprobe_multi_empty.c b/tools/testing/selftests/bpf/progs/kprobe_multi_empty.c > > new file mode 100644 > > index 000000000000..be9e3d891d46 > > --- /dev/null > > +++ b/tools/testing/selftests/bpf/progs/kprobe_multi_empty.c > > @@ -0,0 +1,12 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +#include <linux/bpf.h> > > +#include <bpf/bpf_helpers.h> > > +#include <bpf/bpf_tracing.h> > > + > > +char _license[] SEC("license") = "GPL"; > > + > > +SEC("kprobe.multi/*") > > use SEC("kprobe.multi") to make it clear that we are attaching it "manually"? yep, will do thanks, jirka
diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c index b9876b55fc0c..05f0fab8af89 100644 --- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c +++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c @@ -2,6 +2,9 @@ #include <test_progs.h> #include "kprobe_multi.skel.h" #include "trace_helpers.h" +#include "kprobe_multi_empty.skel.h" +#include "bpf/libbpf_internal.h" +#include "bpf/hashmap.h" static void kprobe_multi_test_run(struct kprobe_multi *skel, bool test_return) { @@ -301,6 +304,137 @@ static void test_attach_api_fails(void) kprobe_multi__destroy(skel); } +static inline __u64 get_time_ns(void) +{ + struct timespec t; + + clock_gettime(CLOCK_MONOTONIC, &t); + return (__u64) t.tv_sec * 1000000000 + t.tv_nsec; +} + +static size_t symbol_hash(const void *key, void *ctx __maybe_unused) +{ + return str_hash((const char *) key); +} + +static bool symbol_equal(const void *key1, const void *key2, void *ctx __maybe_unused) +{ + return strcmp((const char *) key1, (const char *) key2) == 0; +} + +#define DEBUGFS "/sys/kernel/debug/tracing/" + +static int get_syms(char ***symsp, size_t *cntp) +{ + size_t cap = 0, cnt = 0, i; + char *name, **syms = NULL; + struct hashmap *map; + char buf[256]; + FILE *f; + int err; + + /* + * The available_filter_functions contains many duplicates, + * but other than that all symbols are usable in kprobe multi + * interface. + * Filtering out duplicates by using hashmap__add, which won't + * add existing entry. + */ + f = fopen(DEBUGFS "available_filter_functions", "r"); + if (!f) + return -EINVAL; + + map = hashmap__new(symbol_hash, symbol_equal, NULL); + err = libbpf_get_error(map); + if (err) + goto error; + + while (fgets(buf, sizeof(buf), f)) { + /* skip modules */ + if (strchr(buf, '[')) + continue; + if (sscanf(buf, "%ms$*[^\n]\n", &name) != 1) + continue; + err = hashmap__add(map, name, NULL); + if (err) { + free(name); + if (err == -EEXIST) + continue; + goto error; + } + err = libbpf_ensure_mem((void **) &syms, &cap, + sizeof(*syms), cnt + 1); + if (err) { + free(name); + goto error; + } + syms[cnt] = name; + cnt++; + } + + *symsp = syms; + *cntp = cnt; + +error: + fclose(f); + hashmap__free(map); + if (err) { + for (i = 0; i < cnt; i++) + free(syms[cnt]); + free(syms); + } + return err; +} + +static void test_bench_attach(void) +{ + LIBBPF_OPTS(bpf_kprobe_multi_opts, opts); + struct kprobe_multi_empty *skel = NULL; + long attach_start_ns, attach_end_ns; + long detach_start_ns, detach_end_ns; + double attach_delta, detach_delta; + struct bpf_link *link = NULL; + char **syms = NULL; + size_t cnt, i; + + if (!ASSERT_OK(get_syms(&syms, &cnt), "get_syms")) + return; + + skel = kprobe_multi_empty__open_and_load(); + if (!ASSERT_OK_PTR(skel, "kprobe_multi_empty__open_and_load")) + goto cleanup; + + opts.syms = (const char **) syms; + opts.cnt = cnt; + + attach_start_ns = get_time_ns(); + link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe_empty, + NULL, &opts); + attach_end_ns = get_time_ns(); + + if (!ASSERT_OK_PTR(link, "bpf_program__attach_kprobe_multi_opts")) + goto cleanup; + + detach_start_ns = get_time_ns(); + bpf_link__destroy(link); + detach_end_ns = get_time_ns(); + + attach_delta = (attach_end_ns - attach_start_ns) / 1000000000.0; + detach_delta = (detach_end_ns - detach_start_ns) / 1000000000.0; + + fprintf(stderr, "%s: found %lu functions\n", __func__, cnt); + fprintf(stderr, "%s: attached in %7.3lfs\n", __func__, attach_delta); + fprintf(stderr, "%s: detached in %7.3lfs\n", __func__, detach_delta); + +cleanup: + kprobe_multi_empty__destroy(skel); + if (syms) { + for (i = 0; i < cnt; i++) + free(syms[i]); + free(syms); + } +} + void test_kprobe_multi_test(void) { if (!ASSERT_OK(load_kallsyms(), "load_kallsyms")) @@ -320,4 +454,6 @@ void test_kprobe_multi_test(void) test_attach_api_syms(); if (test__start_subtest("attach_api_fails")) test_attach_api_fails(); + if (test__start_subtest("bench_attach")) + test_bench_attach(); } diff --git a/tools/testing/selftests/bpf/progs/kprobe_multi_empty.c b/tools/testing/selftests/bpf/progs/kprobe_multi_empty.c new file mode 100644 index 000000000000..be9e3d891d46 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/kprobe_multi_empty.c @@ -0,0 +1,12 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/bpf.h> +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +char _license[] SEC("license") = "GPL"; + +SEC("kprobe.multi/*") +int test_kprobe_empty(struct pt_regs *ctx) +{ + return 0; +}
Adding test that reads all functions from ftrace available_filter_functions file and attach them all through kprobe_multi API. It also prints stats info with -v option, like on my setup: test_bench_attach: found 48712 functions test_bench_attach: attached in 1.069s test_bench_attach: detached in 0.373s Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- .../bpf/prog_tests/kprobe_multi_test.c | 136 ++++++++++++++++++ .../selftests/bpf/progs/kprobe_multi_empty.c | 12 ++ 2 files changed, 148 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/kprobe_multi_empty.c