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Date: Tue, 16 Sep 2014 03:57:45 -0700 From: tip-bot for Juri Lelli <tipbot@...or.com> To: linux-tip-commits@...r.kernel.org Cc: linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org, henrik@...tad.us, torvalds@...ux-foundation.org, peterz@...radead.org, rdunlap@...radead.org, raistlin@...ux.it, juri.lelli@....com, tglx@...utronix.de, juri.lelli@...il.com Subject: [tip:sched/core] Documentation/scheduler/sched-deadline.txt: Add minimal main() appendix Commit-ID: 13924d2a983fc1557eb737ea59e2324adb538fa2 Gitweb: http://git.kernel.org/tip/13924d2a983fc1557eb737ea59e2324adb538fa2 Author: Juri Lelli <juri.lelli@....com> AuthorDate: Tue, 9 Sep 2014 10:57:16 +0100 Committer: Ingo Molnar <mingo@...nel.org> CommitDate: Tue, 16 Sep 2014 10:23:45 +0200 Documentation/scheduler/sched-deadline.txt: Add minimal main() appendix Add an appendix providing a simple self-contained code snippet showing how SCHED_DEADLINE reservations can be created by application developers. Signed-off-by: Juri Lelli <juri.lelli@....com> Reviewed-by: Henrik Austad <henrik@...tad.us> Cc: Randy Dunlap <rdunlap@...radead.org> Cc: Peter Zijlstra <peterz@...radead.org> Cc: Dario Faggioli <raistlin@...ux.it> Cc: Juri Lelli <juri.lelli@...il.com> Cc: Linus Torvalds <torvalds@...ux-foundation.org> Link: http://lkml.kernel.org/r/1410256636-26171-6-git-send-email-juri.lelli@arm.com [ Fixed some whitespace inconsistencies. ] Signed-off-by: Ingo Molnar <mingo@...nel.org> --- Documentation/scheduler/sched-deadline.txt | 126 +++++++++++++++++++++++++++++ 1 file changed, 126 insertions(+) diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt index b4aad31..21461a0 100644 --- a/Documentation/scheduler/sched-deadline.txt +++ b/Documentation/scheduler/sched-deadline.txt @@ -16,6 +16,7 @@ CONTENTS 5.1 SCHED_DEADLINE and cpusets HOWTO 6. Future plans A. Test suite + B. Minimal main() 0. WARNING @@ -397,3 +398,128 @@ Appendix A. Test suite application, given that you know its pid: # schedtool -E -t 10000000:100000000 my_app_pid + +Appendix B. Minimal main() +========================== + + We provide in what follows a simple (ugly) self-contained code snippet + showing how SCHED_DEADLINE reservations can be created by a real-time + application developer. + + #define _GNU_SOURCE + #include <unistd.h> + #include <stdio.h> + #include <stdlib.h> + #include <string.h> + #include <time.h> + #include <linux/unistd.h> + #include <linux/kernel.h> + #include <linux/types.h> + #include <sys/syscall.h> + #include <pthread.h> + + #define gettid() syscall(__NR_gettid) + + #define SCHED_DEADLINE 6 + + /* XXX use the proper syscall numbers */ + #ifdef __x86_64__ + #define __NR_sched_setattr 314 + #define __NR_sched_getattr 315 + #endif + + #ifdef __i386__ + #define __NR_sched_setattr 351 + #define __NR_sched_getattr 352 + #endif + + #ifdef __arm__ + #define __NR_sched_setattr 380 + #define __NR_sched_getattr 381 + #endif + + static volatile int done; + + struct sched_attr { + __u32 size; + + __u32 sched_policy; + __u64 sched_flags; + + /* SCHED_NORMAL, SCHED_BATCH */ + __s32 sched_nice; + + /* SCHED_FIFO, SCHED_RR */ + __u32 sched_priority; + + /* SCHED_DEADLINE (nsec) */ + __u64 sched_runtime; + __u64 sched_deadline; + __u64 sched_period; + }; + + int sched_setattr(pid_t pid, + const struct sched_attr *attr, + unsigned int flags) + { + return syscall(__NR_sched_setattr, pid, attr, flags); + } + + int sched_getattr(pid_t pid, + struct sched_attr *attr, + unsigned int size, + unsigned int flags) + { + return syscall(__NR_sched_getattr, pid, attr, size, flags); + } + + void *run_deadline(void *data) + { + struct sched_attr attr; + int x = 0; + int ret; + unsigned int flags = 0; + + printf("deadline thread started [%ld]\n", gettid()); + + attr.size = sizeof(attr); + attr.sched_flags = 0; + attr.sched_nice = 0; + attr.sched_priority = 0; + + /* This creates a 10ms/30ms reservation */ + attr.sched_policy = SCHED_DEADLINE; + attr.sched_runtime = 10 * 1000 * 1000; + attr.sched_period = attr.sched_deadline = 30 * 1000 * 1000; + + ret = sched_setattr(0, &attr, flags); + if (ret < 0) { + done = 0; + perror("sched_setattr"); + exit(-1); + } + + while (!done) { + x++; + } + + printf("deadline thread dies [%ld]\n", gettid()); + return NULL; + } + + int main (int argc, char **argv) + { + pthread_t thread; + + printf("main thread [%ld]\n", gettid()); + + pthread_create(&thread, NULL, run_deadline, NULL); + + sleep(10); + + done = 1; + pthread_join(thread, NULL); + + printf("main dies [%ld]\n", gettid()); + return 0; + } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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