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Groups > comp.lang.c++ > #82916
| From | Bonita Montero <Bonita.Montero@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c++ |
| Subject | A little benchmark: |
| Date | 2022-02-05 13:22 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <stlq6s$8pc$1@dont-email.me> (permalink) |
| References | <stj7m4$bim$1@dont-email.me> |
Here's a little benchmark of mine, Tim's and Ben's variant:
I've stipped the construction of the strging-object because
the memory-allocation could be a major part of the operation.
So I'm just returning a pointer into thread local memory.
#include <iostream>
#include <concepts>
#include <array>
#include <cstdio>
#include <cstring>
#include <chrono>
#include <random>
using namespace std;
using namespace chrono;
#if defined(_MSC_VER)
#pragma warning(disable : 4996) // disable deprecated sprintf
#pragma warning(disable : 6200) // array out of range
#endif
template<typename char_t>
requires same_as<char_t, char> || same_as<char_t, wchar_t>
char_t *formatClockCyclesMine( uint64_t clockCycles );
char *formatClockCyclesTim( uint64_t clockCycles );
char *formatClockCyclesBen( uint64_t clockCycles );
int main()
{
auto bench = []<typename FccFn>( FccFn fn )
requires requires( FccFn fn, uint64_t clockCycles ) { { fn(
clockCycles ) } -> same_as<char *>; }
{
static size_t const N = 10'000'000;
char volatile sum = 0;
mt19937_64 mt;
uniform_int_distribution<uint64_t> uid( 0, -1 );
auto start = high_resolution_clock::now();
for( size_t n = N; n--; )
sum += *fn( uid( mt ) + (char)sum );
return (double)(int64_t)duration_cast<nanoseconds>(
high_resolution_clock::now() - start ).count() / (double)N;
};
cout << "mine: " << bench( &formatClockCyclesMine<char> ) << endl;
cout << "Tim: " << bench( formatClockCyclesTim ) << endl;
cout << "Ben: " << bench( formatClockCyclesBen ) << endl;
}
#if defined(_MSC_VER)
#define NOINLINE __declspec(noinline)
#elif defined(__GNUC__) || defined(__llvm__)
#define NOINLINE __attribute__((noinline))
#endif
template<typename char_t>
requires same_as<char_t, char> || same_as<char_t, wchar_t>
NOINLINE
char_t *formatClockCyclesMine( uint64_t clockCycles )
{
using dig_arr_t = array<uint8_t, 20>; // max 20 digits for 64 bit
using dig_arr_it = typename dig_arr_t::iterator;
dig_arr_t reverseDigits;
dig_arr_it rDigitsEnd = reverseDigits.begin();
do
*rDigitsEnd++ = clockCycles % 10,
clockCycles /= 10;
while( clockCycles );
size_t
digitsLen = rDigitsEnd - reverseDigits.begin(),
groups = (digitsLen - 1) / 3;
using str_arr_t = array<char_t, 20 + (20 - 1) / 3 + 1>;
using str_arr_it = typename str_arr_t::iterator;
thread_local str_arr_t str;
str_arr_it wrt = str.begin() + digitsLen + groups;
*wrt = '\0';
dig_arr_it digit = reverseDigits.begin();
for( dig_arr_it groupsEnd = reverseDigits.begin() + groups * 3; digit
!= groupsEnd; wrt -= 4, digit += 3 )
wrt[-1] = digit[0] + '0',
wrt[-2] = digit[1] + '0',
wrt[-3] = digit[2] + '0',
wrt[-4] = '.';
do
*--wrt = *digit++ + '0';
while( digit != rDigitsEnd );
return &*wrt;
}
NOINLINE
char *formatClockCyclesTim( uint64_t clockCycles )
{
thread_local char result[20 + (20 - 1) / 3 + 1];
size_t n = (unsigned)sprintf( result, "%llu", (unsigned long
long)clockCycles );
char *ep = (&result)[1];
*--ep = 0;
while( n > 3 )
memmove( ep -= 3, &result[n -= 3], 3 ),
*--ep = '.';
do
*--ep = result[--n];
while( n );
return ep;
}
NOINLINE
char *formatClockCyclesBen( uint64_t clockCycles )
{
thread_local char result[20 + (20 - 1) / 3 + 1];
char *ep = (&result)[1];
do
{
// initially with a missing cast, actually would have run only on
little endian machines
sprintf( ep - 4, "%03lu", (unsigned long)(clockCycles % 1000) );
if( ep != (&result)[1] )
ep[-1] = '.';
ep -= 4;
} while( clockCycles /= 1000 );
for( ; *ep == '0' && ep[1]; ++ep );
return ep;
}
These are the results with MSVC in ns per operation:
MSVC 2022:
mine: 45.8883
Tim: 129.673
Ben: 562.441
g++ 11.1.0:
mine: 46.0794
Tim: 128.617
Ben: 586.362
clang++ 10.0.0:
mine: 42.8998
Tim: 110.695
Ben: 580.442
Back to comp.lang.c++ | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
C++20 concepts rocks Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-04 13:54 +0100
Re: C++20 concepts rocks Muttley@dastardlyhq.com - 2022-02-04 14:25 +0000
Re: C++20 concepts rocks Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-04 15:31 +0100
Re: C++20 concepts rocks Muttley@dastardlyhq.com - 2022-02-04 14:54 +0000
Re: C++20 concepts rocks Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-04 17:41 +0100
Re: C++20 concepts rocks Muttley@dastardlyhq.com - 2022-02-05 11:31 +0000
Re: C++20 concepts rocks Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-05 12:49 +0100
Re: C++20 concepts rocks Muttley@dastardlyhq.com - 2022-02-05 12:20 +0000
Re: C++20 concepts rocks Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-02-04 16:15 +0000
Re: C++20 concepts rocks Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-04 17:43 +0100
Re: C++20 concepts rocks "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-02-05 01:51 +0100
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Re: C++20 concepts rocks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-04 23:53 -0800
Re: C++20 concepts rocks red floyd <no.spam.here@its.invalid> - 2022-02-05 10:10 -0800
Re: C++20 concepts rocks Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-05 19:51 +0100
Re: C++20 concepts rocks red floyd <no.spam.here@its.invalid> - 2022-02-05 16:42 -0800
Re: C++20 concepts rocks Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-02-06 01:39 +0000
Re: C++20 concepts rocks red floyd <no.spam.here@its.invalid> - 2022-02-05 18:02 -0800
Re: C++20 concepts rocks Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-06 09:57 +0100
Re: C++20 concepts rocks "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-02-06 10:57 +0100
Re: C++20 concepts rocks Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-06 12:40 +0100
Re: C++20 concepts rocks Öö Tiib <ootiib@hot.ee> - 2022-02-06 03:53 -0800
Re: C++20 concepts rocks Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-02-06 14:35 +0000
Re: C++20 concepts rocks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-06 11:20 -0800
Re: C++20 concepts rocks Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-02-06 21:53 +0000
Re: C++20 concepts rocks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-06 19:03 -0800
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Re: C++20 concepts rocks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-07 06:26 -0800
Re: C++20 concepts rocks Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-02-07 15:48 +0000
Re: C++20 concepts rocks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-07 12:16 -0800
Re: C++20 concepts rocks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-07 22:27 -0800
Re: C++20 concepts rocks Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-02-09 21:43 +0000
Re: C++20 concepts rocks James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-02-09 21:07 -0500
Re: C++20 concepts rocks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-09 21:25 -0800
Re: C++20 concepts rocks Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-02-10 13:05 +0000
Re: C++20 concepts rocks James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-02-10 11:19 -0500
Re: C++20 concepts rocks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-11 05:41 -0800
Re: C++20 concepts rocks "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-02-11 17:06 +0100
Re: C++20 concepts rocks James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-02-11 11:50 -0500
Re: C++20 concepts rocks "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-02-11 21:13 +0100
Re: C++20 concepts rocks scott@slp53.sl.home (Scott Lurndal) - 2022-02-11 17:06 +0000
Re: C++20 concepts rocks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-15 00:10 -0800
Re: C++20 concepts rocks "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-02-15 20:58 +0100
Re: C++20 concepts rocks Juha Nieminen <nospam@thanks.invalid> - 2022-02-16 06:40 +0000
Re: C++20 concepts rocks "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-02-16 09:54 +0100
Re: C++20 concepts rocks Muttley@dastardlyhq.com - 2022-02-16 09:00 +0000
Re: C++20 concepts rocks "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-02-16 20:25 +0100
Re: C++20 concepts rocks Muttley@dastardlyhq.com - 2022-02-17 08:53 +0000
Re: C++20 concepts rocks Paavo Helde <eesnimi@osa.pri.ee> - 2022-02-17 16:11 +0200
Re: C++20 concepts rocks James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-02-17 10:58 -0500
Re: C++20 concepts rocks Juha Nieminen <nospam@thanks.invalid> - 2022-02-17 07:32 +0000
Re: C++20 concepts rocks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-04-19 02:21 -0700
Re: C++20 concepts rocks "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-04-19 11:56 +0200
Re: C++20 concepts rocks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-04-25 03:02 -0700
Re: C++20 concepts rocks Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-02-12 00:01 +0000
Re: C++20 concepts rocks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-14 23:55 -0800
Re: C++20 concepts rocks Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-07 18:31 +0100
Re: C++20 concepts rocks scott@slp53.sl.home (Scott Lurndal) - 2022-02-07 17:43 +0000
Re: C++20 concepts rocks James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-02-06 14:25 -0500
Re: C++20 concepts rocks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-06 02:01 -0800
Re: C++20 concepts rocks red floyd <no.spam.here@its.invalid> - 2022-02-06 19:37 -0800
Re: C++20 concepts rocks Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-07 10:18 +0100
Re: C++20 concepts rocks Paavo Helde <eesnimi@osa.pri.ee> - 2022-02-07 11:32 +0200
Re: C++20 concepts rocks red floyd <no.spam.here@its.invalid> - 2022-02-07 07:55 -0800
Re: C++20 concepts rocks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-06 02:11 -0800
Re: C++20 concepts rocks "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-02-06 13:13 +0100
Re: C++20 concepts rocks Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-06 04:58 -0800
Re: C++20 concepts rocks Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-06 14:08 +0100
Re: C++20 concepts rocks Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-05 12:48 +0100
Re: C++20 concepts rocks Juha Nieminen <nospam@thanks.invalid> - 2022-02-04 20:15 +0000
Re: C++20 concepts rocks Muttley@dastardlyhq.com - 2022-02-05 11:32 +0000
Re: C++20 concepts rocks Juha Nieminen <nospam@thanks.invalid> - 2022-02-06 08:28 +0000
Re: C++20 concepts rocks Muttley@dastardlyhq.com - 2022-02-07 09:52 +0000
Re: C++20 concepts rocks Juha Nieminen <nospam@thanks.invalid> - 2022-02-08 07:05 +0000
Re: C++20 concepts rocks Muttley@dastardlyhq.com - 2022-02-08 09:25 +0000
Re: C++20 concepts rocks Juha Nieminen <nospam@thanks.invalid> - 2022-02-08 10:09 +0000
Re: C++20 concepts rocks Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-02-04 12:10 -0800
Re: C++20 concepts rocks Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-05 13:41 +0100
Re: C++20 concepts rocks "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-02-05 19:28 -0800
A little benchmark: Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-05 13:22 +0100
A better benchmark Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-06 14:56 +0100
A improved routine Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-07 15:19 +0100
Re: A better benchmark Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-07 06:57 -0800
Re: A better benchmark Bonita Montero <Bonita.Montero@gmail.com> - 2022-02-07 18:30 +0100
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