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56 lines
1.8 KiB
C++
56 lines
1.8 KiB
C++
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2011.
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This program is free software: you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the Free
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Software Foundation, either version 3 of the License, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details.
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You should have received a copy of the GNU General Public License along with
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this program. If not, see <http://www.gnu.org/licenses/>.
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benchctxswitch.cpp
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Benchmarks the speed of context switches.
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*******************************************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <signal.h>
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#include <unistd.h>
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#include <time.h>
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static int uptime(uintmax_t* usecs)
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{
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struct timespec uptime;
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if ( clock_gettime(CLOCK_BOOT, &uptime) < 0 )
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return -1;
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*usecs = uptime.tv_sec * 1000000ULL + uptime.tv_nsec / 1000ULL;
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return 0;
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}
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int main(int /*argc*/, char* /*argv*/[])
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{
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pid_t slavepid = fork();
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if ( slavepid < 0 ) { perror("fork"); return 1; }
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if ( slavepid == 0 ) { while ( true ) { usleep(0); } exit(0); }
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uintmax_t start;
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if ( uptime(&start) ) { perror("uptime"); return 1; }
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uintmax_t end = start + 1ULL * 1000ULL * 1000ULL; // 1 second
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size_t count = 0;
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uintmax_t now;
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while ( !uptime(&now) && now < end ) { usleep(0); count += 2; /* back and forth */ }
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printf("Made %zu context switches in 1 second\n", count);
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kill(slavepid, SIGKILL);
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return 0;
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}
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