From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753957AbaIPK66 (ORCPT ); Tue, 16 Sep 2014 06:58:58 -0400 Received: from terminus.zytor.com ([198.137.202.10]:43694 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753858AbaIPK6z (ORCPT ); Tue, 16 Sep 2014 06:58:55 -0400 Date: Tue, 16 Sep 2014 03:57:45 -0700 From: tip-bot for Juri Lelli Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, henrik@austad.us, torvalds@linux-foundation.org, peterz@infradead.org, rdunlap@infradead.org, raistlin@linux.it, juri.lelli@arm.com, tglx@linutronix.de, juri.lelli@gmail.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, henrik@austad.us, torvalds@linux-foundation.org, peterz@infradead.org, rdunlap@infradead.org, raistlin@linux.it, juri.lelli@arm.com, tglx@linutronix.de, juri.lelli@gmail.com In-Reply-To: <1410256636-26171-6-git-send-email-juri.lelli@arm.com> References: <1410256636-26171-6-git-send-email-juri.lelli@arm.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] Documentation/scheduler/sched-deadline.txt: Add minimal main() appendix Git-Commit-ID: 13924d2a983fc1557eb737ea59e2324adb538fa2 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 13924d2a983fc1557eb737ea59e2324adb538fa2 Gitweb: http://git.kernel.org/tip/13924d2a983fc1557eb737ea59e2324adb538fa2 Author: Juri Lelli AuthorDate: Tue, 9 Sep 2014 10:57:16 +0100 Committer: Ingo Molnar 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 Reviewed-by: Henrik Austad Cc: Randy Dunlap Cc: Peter Zijlstra Cc: Dario Faggioli Cc: Juri Lelli Cc: Linus Torvalds 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 --- 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 + #include + #include + #include + #include + #include + #include + #include + #include + #include + + #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; + }