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Groups > comp.lang.c++ > #81573
| From | Bonita Montero <Bonita.Montero@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c++ |
| Subject | Re: Some help needed |
| Date | 2021-09-25 19:14 +0200 |
| Organization | A noiseless patient Spider |
| Message-ID | <sinldi$j1h$1@dont-email.me> (permalink) |
| References | <since9$gua$1@dont-email.me> <ir937iFps6uU1@mid.individual.net> |
Am 25.09.2021 um 19:05 schrieb Bo Persson:
>> This is the code:
>>
>> #include <iostream>
>> #include <chrono>
>> #include <cstddef>
>> #include <cstdint>
>> #include <immintrin.h>
>>
>> using namespace std;
>> using namespace chrono;
>>
>> int main( int argc, char **argv )
>> {
>> static uint64_t const PAUSE_ROUNDS = 1'000'000'000;
>> auto start = high_resolution_clock::now();
>> for( uint64_t i = PAUSE_ROUNDS; i; --i )
>> _mm_pause();
>> double ns = (int64_t)duration_cast<nanoseconds>(
>> high_resolution_clock::now() - start ).count() / (double)PAUSE_ROUNDS;
>> cout << ns << endl;
>> }
>
> I get
>
> 30.7635
>
> (Core i9 9900K 5GHz)
Why did AMD decide for such an idiotic timing ? That is neither suitable
for spin-loops with only a single PAUSE-instructions, nor does it save
power while spinning.
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Some help needed Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-25 16:41 +0200
Re: Some help needed Paavo Helde <myfirstname@osa.pri.ee> - 2021-09-25 19:51 +0300
Re: Some help needed Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-25 19:01 +0200
Re: Some help needed Branimir Maksimovic <branimir.maksimovic@gmail.com> - 2021-09-25 17:20 +0000
Re: Some help needed Bo Persson <bo@bo-persson.se> - 2021-09-25 19:05 +0200
Re: Some help needed Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-25 19:14 +0200
Re: Some help needed Branimir Maksimovic <branimir.maksimovic@gmail.com> - 2021-09-25 17:33 +0000
Re: Some help needed Branimir Maksimovic <branimir.maksimovic@gmail.com> - 2021-09-25 17:15 +0000
Re: Some help needed Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-25 19:16 +0200
Re: Some help needed Branimir Maksimovic <branimir.maksimovic@gmail.com> - 2021-09-25 17:29 +0000
Re: Some help needed Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-26 07:26 +0200
Re: Some help needed Branimir Maksimovic <branimir.maksimovic@gmail.com> - 2021-09-26 06:56 +0000
Re: Some help needed - further help Bonita Montero <Bonita.Montero@gmail.com> - 2021-09-27 17:35 +0200
Re: Some help needed - further help Bo Persson <bo@bo-persson.se> - 2021-09-27 19:29 +0200
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