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simplify the benchmark

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This commit is contained in:
Daniel Lemire 2025-12-22 21:08:59 -05:00
parent 62fb615be9
commit 62ed60e95f
2 changed files with 85 additions and 52 deletions
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2
benchmarks/CMakeLists.txt
View File

@ -3,7 +3,7 @@ include(FetchContent)
FetchContent_Declare(
counters
GIT_REPOSITORY https://github.com/lemire/counters.git
GIT_TAG v2.0.0
GIT_TAG v2.1.0
)
FetchContent_MakeAvailable(counters)

135
benchmarks/bench_ip.cpp
View File

@ -26,6 +26,28 @@ void pretty_print(size_t volume, size_t bytes, std::string name,
printf("\n");
}
const char *seek_ip_end(const char *p, const char *pend) {
const char *current = p;
size_t count = 0;
for (; current != pend; ++current) {
if (*current == '.') {
count++;
if (count == 3) {
++current;
break;
}
}
}
while (current != pend) {
if (*current <= '9' && *current >= '0') {
++current;
} else {
break;
}
}
return current;
}
int parse_u8_fastfloat(const char *&p, const char *pend, uint8_t *out) {
if (p == pend)
return 0;
@ -39,8 +61,9 @@ int parse_u8_fastfloat(const char *&p, const char *pend, uint8_t *out) {
static inline int parse_u8_fromchars(const char *&p, const char *pend,
uint8_t *out) {
if (p == pend)
if (p == pend) {
return 0;
}
auto r = std::from_chars(p, pend, *out);
if (r.ec == std::errc()) {
p = r.ptr;
@ -50,26 +73,35 @@ static inline int parse_u8_fromchars(const char *&p, const char *pend,
}
template <typename Parser>
static inline int parse_ip_line(const char *&p, const char *pend, uint32_t &sum,
Parser parse_uint8) {
uint8_t o = 0;
for (int i = 0; i < 4; ++i) {
if (!parse_uint8(p, pend, &o))
return 0;
sum += o;
if (i != 3) {
if (p == pend || *p != '.')
return 0;
++p;
}
std::pair<bool, uint32_t> simple_parse_ip_line(const char *p, const char *pend,
Parser parse_uint8) {
uint8_t v1;
if (!parse_uint8(p, pend, &v1)) {
return {false, 0};
}
// consume optional '\r'
if (p != pend && *p == '\r')
++p;
// expect '\n' or end
if (p != pend && *p == '\n')
++p;
return 1;
if (p == pend || *p++ != '.') {
return {false, 0};
}
uint8_t v2;
if (!parse_uint8(p, pend, &v2)) {
return {false, 0};
}
if (p == pend || *p++ != '.') {
return {false, 0};
}
uint8_t v3;
if (!parse_uint8(p, pend, &v3)) {
return {false, 0};
}
if (p == pend || *p++ != '.') {
return {false, 0};
}
uint8_t v4;
if (!parse_uint8(p, pend, &v4)) {
return {false, 0};
}
return {true, (uint32_t(v1) << 24) | (uint32_t(v2) << 16) |
(uint32_t(v3) << 8) | uint32_t(v4)};
}
static std::string make_ip_line(uint8_t a, uint8_t b, uint8_t c, uint8_t d) {
@ -87,19 +119,22 @@ static std::string make_ip_line(uint8_t a, uint8_t b, uint8_t c, uint8_t d) {
}
int main() {
constexpr size_t N = 500000;
constexpr size_t N = 15000;
std::mt19937 rng(1234);
std::uniform_int_distribution<int> dist(0, 255);
std::string buf;
buf.reserve(N * 16);
constexpr size_t ip_size = 16;
buf.reserve(N * ip_size);
for (size_t i = 0; i < N; ++i) {
uint8_t a = (uint8_t)dist(rng);
uint8_t b = (uint8_t)dist(rng);
uint8_t c = (uint8_t)dist(rng);
uint8_t d = (uint8_t)dist(rng);
buf += make_ip_line(a, b, c, d);
std::string ip_line = make_ip_line(a, b, c, d);
ip_line.resize(ip_size, ' '); // pad to fixed size
buf.append(ip_line);
}
// sentinel to allow 4-byte loads at end
@ -108,30 +143,21 @@ int main() {
const size_t bytes = buf.size() - 4; // exclude sentinel from throughput
const size_t volume = N;
// validate correctness
{
const char *start = buf.data();
const char *end = buf.data() + bytes;
const char *p = start;
const char *pend = end;
uint32_t sum = 0;
for (size_t i = 0; i < N; ++i) {
int ok = parse_ip_line(p, pend, sum, parse_u8_fromchars);
if (!ok) {
std::fprintf(stderr, "fromchars parse failed at line %zu\n", i);
std::abort();
}
p = start;
pend = end;
ok = parse_ip_line(p, pend, sum, parse_u8_fastfloat);
if (!ok) {
std::fprintf(stderr, "fastswar parse failed at line %zu\n", i);
std::abort();
}
}
}
volatile uint32_t sink = 0;
uint32_t sink = 0;
pretty_print(volume, bytes, "just_seek_ip_end (no parse)",
counters::bench([&]() {
const char *p = buf.data();
const char *pend = buf.data() + bytes;
uint32_t sum = 0;
int ok = 0;
for (size_t i = 0; i < N; ++i) {
const char *q = seek_ip_end(p, pend);
sum += (uint32_t)(q - p);
p += ip_size;
}
sink += sum;
}));
pretty_print(volume, bytes, "parse_ip_std_fromchars", counters::bench([&]() {
const char *p = buf.data();
@ -139,9 +165,13 @@ int main() {
uint32_t sum = 0;
int ok = 0;
for (size_t i = 0; i < N; ++i) {
ok = parse_ip_line(p, pend, sum, parse_u8_fromchars);
if (!ok)
auto [ok, ip] =
simple_parse_ip_line(p, pend, parse_u8_fromchars);
sum += ip;
if (!ok) {
std::abort();
}
p += ip_size;
}
sink += sum;
}));
@ -152,13 +182,16 @@ int main() {
uint32_t sum = 0;
int ok = 0;
for (size_t i = 0; i < N; ++i) {
ok = parse_ip_line(p, pend, sum, parse_u8_fastfloat);
if (!ok)
auto [ok, ip] =
simple_parse_ip_line(p, pend, parse_u8_fastfloat);
sum += ip;
if (!ok) {
std::abort();
}
p += ip_size;
}
sink += sum;
}));
std::printf("sink=%u\n", sink);
return EXIT_SUCCESS;
}