From f6e659b7f97c76d0471d12bf274ea2a097cf3c5c Mon Sep 17 00:00:00 2001 From: Joanne Koong Date: Mon, 29 Nov 2021 19:06:21 -0800 Subject: [PATCH] selftests/bpf: Measure bpf_loop verifier performance This patch tests bpf_loop in pyperf and strobemeta, and measures the verifier performance of replacing the traditional for loop with bpf_loop. The results are as follows: ~strobemeta~ Baseline verification time 6808200 usec stack depth 496 processed 554252 insns (limit 1000000) max_states_per_insn 16 total_states 15878 peak_states 13489 mark_read 3110 #192 verif_scale_strobemeta:OK (unrolled loop) Using bpf_loop verification time 31589 usec stack depth 96+400 processed 1513 insns (limit 1000000) max_states_per_insn 2 total_states 106 peak_states 106 mark_read 60 #193 verif_scale_strobemeta_bpf_loop:OK ~pyperf600~ Baseline verification time 29702486 usec stack depth 368 processed 626838 insns (limit 1000000) max_states_per_insn 7 total_states 30368 peak_states 30279 mark_read 748 #182 verif_scale_pyperf600:OK (unrolled loop) Using bpf_loop verification time 148488 usec stack depth 320+40 processed 10518 insns (limit 1000000) max_states_per_insn 10 total_states 705 peak_states 517 mark_read 38 #183 verif_scale_pyperf600_bpf_loop:OK Using the bpf_loop helper led to approximately a 99% decrease in the verification time and in the number of instructions. Signed-off-by: Joanne Koong Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20211130030622.4131246-4-joannekoong@fb.com --- .../selftests/bpf/prog_tests/bpf_verif_scale.c | 12 ++++ tools/testing/selftests/bpf/progs/pyperf.h | 71 +++++++++++++++++++- .../selftests/bpf/progs/pyperf600_bpf_loop.c | 6 ++ tools/testing/selftests/bpf/progs/strobemeta.h | 75 +++++++++++++++++++++- .../selftests/bpf/progs/strobemeta_bpf_loop.c | 9 +++ 5 files changed, 169 insertions(+), 4 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/pyperf600_bpf_loop.c create mode 100644 tools/testing/selftests/bpf/progs/strobemeta_bpf_loop.c diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c b/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c index 27f5d8e..1fb16f8 100644 --- a/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c +++ b/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c @@ -115,6 +115,12 @@ void test_verif_scale_pyperf600() scale_test("pyperf600.o", BPF_PROG_TYPE_RAW_TRACEPOINT, false); } +void test_verif_scale_pyperf600_bpf_loop(void) +{ + /* use the bpf_loop helper*/ + scale_test("pyperf600_bpf_loop.o", BPF_PROG_TYPE_RAW_TRACEPOINT, false); +} + void test_verif_scale_pyperf600_nounroll() { /* no unroll at all. @@ -165,6 +171,12 @@ void test_verif_scale_strobemeta() scale_test("strobemeta.o", BPF_PROG_TYPE_RAW_TRACEPOINT, false); } +void test_verif_scale_strobemeta_bpf_loop(void) +{ + /* use the bpf_loop helper*/ + scale_test("strobemeta_bpf_loop.o", BPF_PROG_TYPE_RAW_TRACEPOINT, false); +} + void test_verif_scale_strobemeta_nounroll1() { /* no unroll, tiny loops */ diff --git a/tools/testing/selftests/bpf/progs/pyperf.h b/tools/testing/selftests/bpf/progs/pyperf.h index 2fb7ada..1ed2888 100644 --- a/tools/testing/selftests/bpf/progs/pyperf.h +++ b/tools/testing/selftests/bpf/progs/pyperf.h @@ -159,6 +159,59 @@ struct { __uint(value_size, sizeof(long long) * 127); } stackmap SEC(".maps"); +#ifdef USE_BPF_LOOP +struct process_frame_ctx { + int cur_cpu; + int32_t *symbol_counter; + void *frame_ptr; + FrameData *frame; + PidData *pidData; + Symbol *sym; + Event *event; + bool done; +}; + +#define barrier_var(var) asm volatile("" : "=r"(var) : "0"(var)) + +static int process_frame_callback(__u32 i, struct process_frame_ctx *ctx) +{ + int zero = 0; + void *frame_ptr = ctx->frame_ptr; + PidData *pidData = ctx->pidData; + FrameData *frame = ctx->frame; + int32_t *symbol_counter = ctx->symbol_counter; + int cur_cpu = ctx->cur_cpu; + Event *event = ctx->event; + Symbol *sym = ctx->sym; + + if (frame_ptr && get_frame_data(frame_ptr, pidData, frame, sym)) { + int32_t new_symbol_id = *symbol_counter * 64 + cur_cpu; + int32_t *symbol_id = bpf_map_lookup_elem(&symbolmap, sym); + + if (!symbol_id) { + bpf_map_update_elem(&symbolmap, sym, &zero, 0); + symbol_id = bpf_map_lookup_elem(&symbolmap, sym); + if (!symbol_id) { + ctx->done = true; + return 1; + } + } + if (*symbol_id == new_symbol_id) + (*symbol_counter)++; + + barrier_var(i); + if (i >= STACK_MAX_LEN) + return 1; + + event->stack[i] = *symbol_id; + + event->stack_len = i + 1; + frame_ptr = frame->f_back; + } + return 0; +} +#endif /* USE_BPF_LOOP */ + #ifdef GLOBAL_FUNC __noinline #elif defined(SUBPROGS) @@ -228,11 +281,26 @@ int __on_event(struct bpf_raw_tracepoint_args *ctx) int32_t* symbol_counter = bpf_map_lookup_elem(&symbolmap, &sym); if (symbol_counter == NULL) return 0; +#ifdef USE_BPF_LOOP + struct process_frame_ctx ctx = { + .cur_cpu = cur_cpu, + .symbol_counter = symbol_counter, + .frame_ptr = frame_ptr, + .frame = &frame, + .pidData = pidData, + .sym = &sym, + .event = event, + }; + + bpf_loop(STACK_MAX_LEN, process_frame_callback, &ctx, 0); + if (ctx.done) + return 0; +#else #ifdef NO_UNROLL #pragma clang loop unroll(disable) #else #pragma clang loop unroll(full) -#endif +#endif /* NO_UNROLL */ /* Unwind python stack */ for (int i = 0; i < STACK_MAX_LEN; ++i) { if (frame_ptr && get_frame_data(frame_ptr, pidData, &frame, &sym)) { @@ -251,6 +319,7 @@ int __on_event(struct bpf_raw_tracepoint_args *ctx) frame_ptr = frame.f_back; } } +#endif /* USE_BPF_LOOP */ event->stack_complete = frame_ptr == NULL; } else { event->stack_complete = 1; diff --git a/tools/testing/selftests/bpf/progs/pyperf600_bpf_loop.c b/tools/testing/selftests/bpf/progs/pyperf600_bpf_loop.c new file mode 100644 index 0000000..5c2059d --- /dev/null +++ b/tools/testing/selftests/bpf/progs/pyperf600_bpf_loop.c @@ -0,0 +1,6 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2021 Facebook */ + +#define STACK_MAX_LEN 600 +#define USE_BPF_LOOP +#include "pyperf.h" diff --git a/tools/testing/selftests/bpf/progs/strobemeta.h b/tools/testing/selftests/bpf/progs/strobemeta.h index 60c93ae..7537185 100644 --- a/tools/testing/selftests/bpf/progs/strobemeta.h +++ b/tools/testing/selftests/bpf/progs/strobemeta.h @@ -445,6 +445,48 @@ static __always_inline void *read_map_var(struct strobemeta_cfg *cfg, return payload; } +#ifdef USE_BPF_LOOP +enum read_type { + READ_INT_VAR, + READ_MAP_VAR, + READ_STR_VAR, +}; + +struct read_var_ctx { + struct strobemeta_payload *data; + void *tls_base; + struct strobemeta_cfg *cfg; + void *payload; + /* value gets mutated */ + struct strobe_value_generic *value; + enum read_type type; +}; + +static int read_var_callback(__u32 index, struct read_var_ctx *ctx) +{ + switch (ctx->type) { + case READ_INT_VAR: + if (index >= STROBE_MAX_INTS) + return 1; + read_int_var(ctx->cfg, index, ctx->tls_base, ctx->value, ctx->data); + break; + case READ_MAP_VAR: + if (index >= STROBE_MAX_MAPS) + return 1; + ctx->payload = read_map_var(ctx->cfg, index, ctx->tls_base, + ctx->value, ctx->data, ctx->payload); + break; + case READ_STR_VAR: + if (index >= STROBE_MAX_STRS) + return 1; + ctx->payload += read_str_var(ctx->cfg, index, ctx->tls_base, + ctx->value, ctx->data, ctx->payload); + break; + } + return 0; +} +#endif /* USE_BPF_LOOP */ + /* * read_strobe_meta returns NULL, if no metadata was read; otherwise returns * pointer to *right after* payload ends @@ -475,11 +517,36 @@ static void *read_strobe_meta(struct task_struct *task, */ tls_base = (void *)task; +#ifdef USE_BPF_LOOP + struct read_var_ctx ctx = { + .cfg = cfg, + .tls_base = tls_base, + .value = &value, + .data = data, + .payload = payload, + }; + int err; + + ctx.type = READ_INT_VAR; + err = bpf_loop(STROBE_MAX_INTS, read_var_callback, &ctx, 0); + if (err != STROBE_MAX_INTS) + return NULL; + + ctx.type = READ_STR_VAR; + err = bpf_loop(STROBE_MAX_STRS, read_var_callback, &ctx, 0); + if (err != STROBE_MAX_STRS) + return NULL; + + ctx.type = READ_MAP_VAR; + err = bpf_loop(STROBE_MAX_MAPS, read_var_callback, &ctx, 0); + if (err != STROBE_MAX_MAPS) + return NULL; +#else #ifdef NO_UNROLL #pragma clang loop unroll(disable) #else #pragma unroll -#endif +#endif /* NO_UNROLL */ for (int i = 0; i < STROBE_MAX_INTS; ++i) { read_int_var(cfg, i, tls_base, &value, data); } @@ -487,7 +554,7 @@ static void *read_strobe_meta(struct task_struct *task, #pragma clang loop unroll(disable) #else #pragma unroll -#endif +#endif /* NO_UNROLL */ for (int i = 0; i < STROBE_MAX_STRS; ++i) { payload += read_str_var(cfg, i, tls_base, &value, data, payload); } @@ -495,10 +562,12 @@ static void *read_strobe_meta(struct task_struct *task, #pragma clang loop unroll(disable) #else #pragma unroll -#endif +#endif /* NO_UNROLL */ for (int i = 0; i < STROBE_MAX_MAPS; ++i) { payload = read_map_var(cfg, i, tls_base, &value, data, payload); } +#endif /* USE_BPF_LOOP */ + /* * return pointer right after end of payload, so it's possible to * calculate exact amount of useful data that needs to be sent diff --git a/tools/testing/selftests/bpf/progs/strobemeta_bpf_loop.c b/tools/testing/selftests/bpf/progs/strobemeta_bpf_loop.c new file mode 100644 index 0000000..d18b992 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/strobemeta_bpf_loop.c @@ -0,0 +1,9 @@ +// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) +/* Copyright (c) 2021 Facebook */ + +#define STROBE_MAX_INTS 2 +#define STROBE_MAX_STRS 25 +#define STROBE_MAX_MAPS 100 +#define STROBE_MAX_MAP_ENTRIES 20 +#define USE_BPF_LOOP +#include "strobemeta.h" -- 2.7.4