| Message ID | 20211130142215.1237217-5-houtao1@huawei.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | introduce bpf_strncmp() helper | expand |
On Tue, Nov 30, 2021 at 6:07 AM Hou Tao <houtao1@huawei.com> wrote: > > Add benchmark to compare the performance between home-made strncmp() > in bpf program and bpf_strncmp() helper. In summary, the performance > win of bpf_strncmp() under x86-64 is greater than 18% when the compared > string length is greater than 64, and is 179% when the length is 4095. > Under arm64 the performance win is even bigger: 33% when the length > is greater than 64 and 600% when the length is 4095. > > The following is the details: > > no-helper-X: use home-made strncmp() to compare X-sized string > helper-Y: use bpf_strncmp() to compare Y-sized string > > Under x86-64: > > no-helper-1 3.504 ± 0.000M/s (drops 0.000 ± 0.000M/s) > helper-1 3.347 ± 0.001M/s (drops 0.000 ± 0.000M/s) > > no-helper-8 3.357 ± 0.001M/s (drops 0.000 ± 0.000M/s) > helper-8 3.307 ± 0.001M/s (drops 0.000 ± 0.000M/s) > > no-helper-32 3.064 ± 0.000M/s (drops 0.000 ± 0.000M/s) > helper-32 3.253 ± 0.001M/s (drops 0.000 ± 0.000M/s) > > no-helper-64 2.563 ± 0.001M/s (drops 0.000 ± 0.000M/s) > helper-64 3.040 ± 0.001M/s (drops 0.000 ± 0.000M/s) > > no-helper-128 1.975 ± 0.000M/s (drops 0.000 ± 0.000M/s) > helper-128 2.641 ± 0.000M/s (drops 0.000 ± 0.000M/s) > > no-helper-512 0.759 ± 0.000M/s (drops 0.000 ± 0.000M/s) > helper-512 1.574 ± 0.000M/s (drops 0.000 ± 0.000M/s) > > no-helper-2048 0.329 ± 0.000M/s (drops 0.000 ± 0.000M/s) > helper-2048 0.602 ± 0.000M/s (drops 0.000 ± 0.000M/s) > > no-helper-4095 0.117 ± 0.000M/s (drops 0.000 ± 0.000M/s) > helper-4095 0.327 ± 0.000M/s (drops 0.000 ± 0.000M/s) > > Under arm64: > > no-helper-1 2.806 ± 0.004M/s (drops 0.000 ± 0.000M/s) > helper-1 2.819 ± 0.002M/s (drops 0.000 ± 0.000M/s) > > no-helper-8 2.797 ± 0.109M/s (drops 0.000 ± 0.000M/s) > helper-8 2.786 ± 0.025M/s (drops 0.000 ± 0.000M/s) > > no-helper-32 2.399 ± 0.011M/s (drops 0.000 ± 0.000M/s) > helper-32 2.703 ± 0.002M/s (drops 0.000 ± 0.000M/s) > > no-helper-64 2.020 ± 0.015M/s (drops 0.000 ± 0.000M/s) > helper-64 2.702 ± 0.073M/s (drops 0.000 ± 0.000M/s) > > no-helper-128 1.604 ± 0.001M/s (drops 0.000 ± 0.000M/s) > helper-128 2.516 ± 0.002M/s (drops 0.000 ± 0.000M/s) > > no-helper-512 0.699 ± 0.000M/s (drops 0.000 ± 0.000M/s) > helper-512 2.106 ± 0.003M/s (drops 0.000 ± 0.000M/s) > > no-helper-2048 0.215 ± 0.000M/s (drops 0.000 ± 0.000M/s) > helper-2048 1.223 ± 0.003M/s (drops 0.000 ± 0.000M/s) > > no-helper-4095 0.112 ± 0.000M/s (drops 0.000 ± 0.000M/s) > helper-4095 0.796 ± 0.000M/s (drops 0.000 ± 0.000M/s) > > Signed-off-by: Hou Tao <houtao1@huawei.com> > --- > tools/testing/selftests/bpf/Makefile | 4 +- > tools/testing/selftests/bpf/bench.c | 6 + > .../selftests/bpf/benchs/bench_strncmp.c | 150 ++++++++++++++++++ > .../selftests/bpf/benchs/run_bench_strncmp.sh | 12 ++ > .../selftests/bpf/progs/strncmp_bench.c | 50 ++++++ > 5 files changed, 221 insertions(+), 1 deletion(-) > create mode 100644 tools/testing/selftests/bpf/benchs/bench_strncmp.c > create mode 100755 tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh > create mode 100644 tools/testing/selftests/bpf/progs/strncmp_bench.c > [...] > diff --git a/tools/testing/selftests/bpf/progs/strncmp_bench.c b/tools/testing/selftests/bpf/progs/strncmp_bench.c > new file mode 100644 > index 000000000000..18373a7df76e > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/strncmp_bench.c > @@ -0,0 +1,50 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (C) 2021. Huawei Technologies Co., Ltd */ > +#include <linux/types.h> > +#include <linux/bpf.h> > +#include <bpf/bpf_helpers.h> > +#include <bpf/bpf_tracing.h> > + > +#define STRNCMP_STR_SZ 4096 > + > +/* Will be updated by benchmark before program loading */ > +const volatile unsigned int cmp_str_len = 1; > +const char target[STRNCMP_STR_SZ]; > + > +long hits = 0; > +char str[STRNCMP_STR_SZ]; > + > +char _license[] SEC("license") = "GPL"; > + > +static __always_inline int local_strncmp(const char *s1, unsigned int sz, > + const char *s2) > +{ > + int ret = 0; > + unsigned int i; > + > + for (i = 0; i < sz; i++) { > + /* E.g. 0xff > 0x31 */ > + ret = (unsigned char)s1[i] - (unsigned char)s2[i]; I'm actually not sure if it will perform subtraction in unsigned form (and thus you'll never have a negative result) and then cast to int, or not. Why not cast to int instead of unsigned char to be sure? > + if (ret || !s1[i]) > + break; > + } > + > + return ret; > +} > + > +SEC("tp/syscalls/sys_enter_getpgid") > +int strncmp_no_helper(void *ctx) > +{ > + if (local_strncmp(str, cmp_str_len + 1, target) < 0) > + __sync_add_and_fetch(&hits, 1); > + return 0; > +} > + > +SEC("tp/syscalls/sys_enter_getpgid") > +int strncmp_helper(void *ctx) > +{ > + if (bpf_strncmp(str, cmp_str_len + 1, target) < 0) > + __sync_add_and_fetch(&hits, 1); > + return 0; > +} > + > -- > 2.29.2 >
Hi, On 12/7/2021 11:01 AM, Andrii Nakryiko wrote: > On Tue, Nov 30, 2021 at 6:07 AM Hou Tao <houtao1@huawei.com> wrote: >> Add benchmark to compare the performance between home-made strncmp() >> in bpf program and bpf_strncmp() helper. In summary, the performance >> win of bpf_strncmp() under x86-64 is greater than 18% when the compared >> string length is greater than 64, and is 179% when the length is 4095. >> Under arm64 the performance win is even bigger: 33% when the length >> is greater than 64 and 600% when the length is 4095. snip >> + >> +long hits = 0; >> +char str[STRNCMP_STR_SZ]; >> + >> +char _license[] SEC("license") = "GPL"; >> + >> +static __always_inline int local_strncmp(const char *s1, unsigned int sz, >> + const char *s2) >> +{ >> + int ret = 0; >> + unsigned int i; >> + >> + for (i = 0; i < sz; i++) { >> + /* E.g. 0xff > 0x31 */ >> + ret = (unsigned char)s1[i] - (unsigned char)s2[i]; > I'm actually not sure if it will perform subtraction in unsigned form > (and thus you'll never have a negative result) and then cast to int, > or not. Why not cast to int instead of unsigned char to be sure? It is used to handle the character which is greater than or equal with 0x80. When casting these character into int, the result will be a negative value, the compare result will always be negative and it is wrong because 0xff should be greater than 0x31.
On Wed, Dec 8, 2021 at 5:47 AM Hou Tao <houtao1@huawei.com> wrote: > > Hi, > > On 12/7/2021 11:01 AM, Andrii Nakryiko wrote: > > On Tue, Nov 30, 2021 at 6:07 AM Hou Tao <houtao1@huawei.com> wrote: > >> Add benchmark to compare the performance between home-made strncmp() > >> in bpf program and bpf_strncmp() helper. In summary, the performance > >> win of bpf_strncmp() under x86-64 is greater than 18% when the compared > >> string length is greater than 64, and is 179% when the length is 4095. > >> Under arm64 the performance win is even bigger: 33% when the length > >> is greater than 64 and 600% when the length is 4095. > snip > >> + > >> +long hits = 0; > >> +char str[STRNCMP_STR_SZ]; > >> + > >> +char _license[] SEC("license") = "GPL"; > >> + > >> +static __always_inline int local_strncmp(const char *s1, unsigned int sz, > >> + const char *s2) > >> +{ > >> + int ret = 0; > >> + unsigned int i; > >> + > >> + for (i = 0; i < sz; i++) { > >> + /* E.g. 0xff > 0x31 */ > >> + ret = (unsigned char)s1[i] - (unsigned char)s2[i]; > > I'm actually not sure if it will perform subtraction in unsigned form > > (and thus you'll never have a negative result) and then cast to int, > > or not. Why not cast to int instead of unsigned char to be sure? > It is used to handle the character which is greater than or equal with 0x80. > When casting these character into int, the result will be a negative value, > the compare result will always be negative and it is wrong because > 0xff should be greater than 0x31. I see about (unsigned char) cast, but I was worried that subtraction result won't be negative I've tested with $ cat test.c #include <stdio.h> int main() { int x = (unsigned char)190 - (unsigned char)255; printf("%d\n", x); } Seems like it behaves sanely (at least on this particular compiler), so I'm fine with it.
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 8ff7060fe754..7719924b01a3 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -531,6 +531,7 @@ $(OUTPUT)/bench_trigger.o: $(OUTPUT)/trigger_bench.skel.h $(OUTPUT)/bench_ringbufs.o: $(OUTPUT)/ringbuf_bench.skel.h \ $(OUTPUT)/perfbuf_bench.skel.h $(OUTPUT)/bench_bloom_filter_map.o: $(OUTPUT)/bloom_filter_bench.skel.h +$(OUTPUT)/bench_strncmp.o: $(OUTPUT)/strncmp_bench.skel.h $(OUTPUT)/bench.o: bench.h testing_helpers.h $(BPFOBJ) $(OUTPUT)/bench: LDLIBS += -lm $(OUTPUT)/bench: $(OUTPUT)/bench.o \ @@ -540,7 +541,8 @@ $(OUTPUT)/bench: $(OUTPUT)/bench.o \ $(OUTPUT)/bench_rename.o \ $(OUTPUT)/bench_trigger.o \ $(OUTPUT)/bench_ringbufs.o \ - $(OUTPUT)/bench_bloom_filter_map.o + $(OUTPUT)/bench_bloom_filter_map.o \ + $(OUTPUT)/bench_strncmp.o $(call msg,BINARY,,$@) $(Q)$(CC) $(LDFLAGS) $(filter %.a %.o,$^) $(LDLIBS) -o $@ diff --git a/tools/testing/selftests/bpf/bench.c b/tools/testing/selftests/bpf/bench.c index 681db8175fe1..8f1a4351fb18 100644 --- a/tools/testing/selftests/bpf/bench.c +++ b/tools/testing/selftests/bpf/bench.c @@ -184,10 +184,12 @@ static const struct argp_option opts[] = { extern struct argp bench_ringbufs_argp; extern struct argp bench_bloom_map_argp; +extern struct argp strncmp_argp; static const struct argp_child bench_parsers[] = { { &bench_ringbufs_argp, 0, "Ring buffers benchmark", 0 }, { &bench_bloom_map_argp, 0, "Bloom filter map benchmark", 0 }, + { &strncmp_argp, 0, "Strncmp benchmark", 0 }, {}, }; @@ -386,6 +388,8 @@ extern const struct bench bench_bloom_update; extern const struct bench bench_bloom_false_positive; extern const struct bench bench_hashmap_without_bloom; extern const struct bench bench_hashmap_with_bloom; +extern const struct bench bench_strncmp_no_helper; +extern const struct bench bench_strncmp_helper; static const struct bench *benchs[] = { &bench_count_global, @@ -417,6 +421,8 @@ static const struct bench *benchs[] = { &bench_bloom_false_positive, &bench_hashmap_without_bloom, &bench_hashmap_with_bloom, + &bench_strncmp_no_helper, + &bench_strncmp_helper, }; static void setup_benchmark() diff --git a/tools/testing/selftests/bpf/benchs/bench_strncmp.c b/tools/testing/selftests/bpf/benchs/bench_strncmp.c new file mode 100644 index 000000000000..57dea095e27a --- /dev/null +++ b/tools/testing/selftests/bpf/benchs/bench_strncmp.c @@ -0,0 +1,150 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2021. Huawei Technologies Co., Ltd */ +#include <argp.h> +#include "bench.h" +#include "strncmp_bench.skel.h" + +struct strncmp_ctx { + struct strncmp_bench *skel; +}; + +struct strncmp_args { + u32 cmp_str_len; +}; + +static struct strncmp_args args = { + .cmp_str_len = 32, +}; + +static struct strncmp_ctx ctx; + +enum { + ARG_CMP_STR_LEN = 4000, +}; + +static const struct argp_option opts[] = { + { "cmp-str-len", ARG_CMP_STR_LEN, "CMP_STR_LEN", 0, + "Set the length of compared string" }, + {}, +}; + +static error_t strncmp_parse_arg(int key, char *arg, struct argp_state *state) +{ + switch (key) { + case ARG_CMP_STR_LEN: + args.cmp_str_len = strtoul(arg, NULL, 10); + if (!args.cmp_str_len || + args.cmp_str_len >= sizeof(ctx.skel->bss->str)) { + fprintf(stderr, "Invalid cmp str len (limit %zu)\n", + sizeof(ctx.skel->bss->str)); + argp_usage(state); + } + break; + default: + return ARGP_ERR_UNKNOWN; + } + + return 0; +} + +const struct argp strncmp_argp = { + .options = opts, + .parser = strncmp_parse_arg, +}; + +static void strncmp_validate(void) +{ + assert_single_consumer("strncmp"); +} + +static void strncmp_setup(void) +{ + int err; + char *target; + size_t i, sz; + + sz = sizeof(ctx.skel->rodata->target); + if (!sz || sz < sizeof(ctx.skel->bss->str)) { + fprintf(stderr, "invalid string size (target %zu, src %zu)\n", + sz, sizeof(ctx.skel->bss->str)); + exit(1); + } + + setup_libbpf(); + + ctx.skel = strncmp_bench__open(); + if (!ctx.skel) { + fprintf(stderr, "failed to open skeleton\n"); + exit(1); + } + + srandom(time(NULL)); + target = ctx.skel->rodata->target; + for (i = 0; i < sz - 1; i++) + target[i] = '1' + random() % 9; + target[sz - 1] = '\0'; + + ctx.skel->rodata->cmp_str_len = args.cmp_str_len; + + memcpy(ctx.skel->bss->str, target, args.cmp_str_len); + ctx.skel->bss->str[args.cmp_str_len] = '\0'; + /* Make bss->str < rodata->target */ + ctx.skel->bss->str[args.cmp_str_len - 1] -= 1; + + err = strncmp_bench__load(ctx.skel); + if (err) { + fprintf(stderr, "failed to load skeleton\n"); + strncmp_bench__destroy(ctx.skel); + exit(1); + } +} + +static void strncmp_attach_prog(struct bpf_program *prog) +{ + struct bpf_link *link; + + link = bpf_program__attach(prog); + if (!link) { + fprintf(stderr, "failed to attach program!\n"); + exit(1); + } +} + +static void strncmp_no_helper_setup(void) +{ + strncmp_setup(); + strncmp_attach_prog(ctx.skel->progs.strncmp_no_helper); +} + +static void strncmp_helper_setup(void) +{ + strncmp_setup(); + strncmp_attach_prog(ctx.skel->progs.strncmp_helper); +} + +static void strncmp_measure(struct bench_res *res) +{ + res->hits = atomic_swap(&ctx.skel->bss->hits, 0); +} + +const struct bench bench_strncmp_no_helper = { + .name = "strncmp-no-helper", + .validate = strncmp_validate, + .setup = strncmp_no_helper_setup, + .producer_thread = getpgid_loop_producer, + .consumer_thread = noop_consumer, + .measure = strncmp_measure, + .report_progress = hits_drops_report_progress, + .report_final = hits_drops_report_final, +}; + +const struct bench bench_strncmp_helper = { + .name = "strncmp-helper", + .validate = strncmp_validate, + .setup = strncmp_helper_setup, + .producer_thread = getpgid_loop_producer, + .consumer_thread = noop_consumer, + .measure = strncmp_measure, + .report_progress = hits_drops_report_progress, + .report_final = hits_drops_report_final, +}; diff --git a/tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh b/tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh new file mode 100755 index 000000000000..142697284b45 --- /dev/null +++ b/tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh @@ -0,0 +1,12 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 + +source ./benchs/run_common.sh + +set -eufo pipefail + +for s in 1 8 64 512 2048 4095; do + for b in no-helper helper; do + summarize ${b}-${s} "$($RUN_BENCH --cmp-str-len=$s strncmp-${b})" + done +done diff --git a/tools/testing/selftests/bpf/progs/strncmp_bench.c b/tools/testing/selftests/bpf/progs/strncmp_bench.c new file mode 100644 index 000000000000..18373a7df76e --- /dev/null +++ b/tools/testing/selftests/bpf/progs/strncmp_bench.c @@ -0,0 +1,50 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2021. Huawei Technologies Co., Ltd */ +#include <linux/types.h> +#include <linux/bpf.h> +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +#define STRNCMP_STR_SZ 4096 + +/* Will be updated by benchmark before program loading */ +const volatile unsigned int cmp_str_len = 1; +const char target[STRNCMP_STR_SZ]; + +long hits = 0; +char str[STRNCMP_STR_SZ]; + +char _license[] SEC("license") = "GPL"; + +static __always_inline int local_strncmp(const char *s1, unsigned int sz, + const char *s2) +{ + int ret = 0; + unsigned int i; + + for (i = 0; i < sz; i++) { + /* E.g. 0xff > 0x31 */ + ret = (unsigned char)s1[i] - (unsigned char)s2[i]; + if (ret || !s1[i]) + break; + } + + return ret; +} + +SEC("tp/syscalls/sys_enter_getpgid") +int strncmp_no_helper(void *ctx) +{ + if (local_strncmp(str, cmp_str_len + 1, target) < 0) + __sync_add_and_fetch(&hits, 1); + return 0; +} + +SEC("tp/syscalls/sys_enter_getpgid") +int strncmp_helper(void *ctx) +{ + if (bpf_strncmp(str, cmp_str_len + 1, target) < 0) + __sync_add_and_fetch(&hits, 1); + return 0; +} +
Add benchmark to compare the performance between home-made strncmp() in bpf program and bpf_strncmp() helper. In summary, the performance win of bpf_strncmp() under x86-64 is greater than 18% when the compared string length is greater than 64, and is 179% when the length is 4095. Under arm64 the performance win is even bigger: 33% when the length is greater than 64 and 600% when the length is 4095. The following is the details: no-helper-X: use home-made strncmp() to compare X-sized string helper-Y: use bpf_strncmp() to compare Y-sized string Under x86-64: no-helper-1 3.504 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper-1 3.347 ± 0.001M/s (drops 0.000 ± 0.000M/s) no-helper-8 3.357 ± 0.001M/s (drops 0.000 ± 0.000M/s) helper-8 3.307 ± 0.001M/s (drops 0.000 ± 0.000M/s) no-helper-32 3.064 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper-32 3.253 ± 0.001M/s (drops 0.000 ± 0.000M/s) no-helper-64 2.563 ± 0.001M/s (drops 0.000 ± 0.000M/s) helper-64 3.040 ± 0.001M/s (drops 0.000 ± 0.000M/s) no-helper-128 1.975 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper-128 2.641 ± 0.000M/s (drops 0.000 ± 0.000M/s) no-helper-512 0.759 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper-512 1.574 ± 0.000M/s (drops 0.000 ± 0.000M/s) no-helper-2048 0.329 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper-2048 0.602 ± 0.000M/s (drops 0.000 ± 0.000M/s) no-helper-4095 0.117 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper-4095 0.327 ± 0.000M/s (drops 0.000 ± 0.000M/s) Under arm64: no-helper-1 2.806 ± 0.004M/s (drops 0.000 ± 0.000M/s) helper-1 2.819 ± 0.002M/s (drops 0.000 ± 0.000M/s) no-helper-8 2.797 ± 0.109M/s (drops 0.000 ± 0.000M/s) helper-8 2.786 ± 0.025M/s (drops 0.000 ± 0.000M/s) no-helper-32 2.399 ± 0.011M/s (drops 0.000 ± 0.000M/s) helper-32 2.703 ± 0.002M/s (drops 0.000 ± 0.000M/s) no-helper-64 2.020 ± 0.015M/s (drops 0.000 ± 0.000M/s) helper-64 2.702 ± 0.073M/s (drops 0.000 ± 0.000M/s) no-helper-128 1.604 ± 0.001M/s (drops 0.000 ± 0.000M/s) helper-128 2.516 ± 0.002M/s (drops 0.000 ± 0.000M/s) no-helper-512 0.699 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper-512 2.106 ± 0.003M/s (drops 0.000 ± 0.000M/s) no-helper-2048 0.215 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper-2048 1.223 ± 0.003M/s (drops 0.000 ± 0.000M/s) no-helper-4095 0.112 ± 0.000M/s (drops 0.000 ± 0.000M/s) helper-4095 0.796 ± 0.000M/s (drops 0.000 ± 0.000M/s) Signed-off-by: Hou Tao <houtao1@huawei.com> --- tools/testing/selftests/bpf/Makefile | 4 +- tools/testing/selftests/bpf/bench.c | 6 + .../selftests/bpf/benchs/bench_strncmp.c | 150 ++++++++++++++++++ .../selftests/bpf/benchs/run_bench_strncmp.sh | 12 ++ .../selftests/bpf/progs/strncmp_bench.c | 50 ++++++ 5 files changed, 221 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/bpf/benchs/bench_strncmp.c create mode 100755 tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh create mode 100644 tools/testing/selftests/bpf/progs/strncmp_bench.c