From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756476AbaIIJ7C (ORCPT ); Tue, 9 Sep 2014 05:59:02 -0400 Received: from service87.mimecast.com ([91.220.42.44]:43118 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756128AbaIIJ5I (ORCPT ); Tue, 9 Sep 2014 05:57:08 -0400 From: Juri Lelli To: peterz@infradead.org Cc: luca.abeni@unitn.it, rdunlap@infradead.org, mingo@redhat.com, henrik@austad.us, raistlin@linux.it, juri.lelli@gmail.com, juri.lelli@arm.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 5/5] Documentation/scheduler/sched-deadline.txt: add minimal main() appendix Date: Tue, 9 Sep 2014 10:57:16 +0100 Message-Id: <1410256636-26171-6-git-send-email-juri.lelli@arm.com> X-Mailer: git-send-email 2.0.4 In-Reply-To: <1410256636-26171-1-git-send-email-juri.lelli@arm.com> References: <1410256636-26171-1-git-send-email-juri.lelli@arm.com> X-OriginalArrivalTime: 09 Sep 2014 09:57:04.0892 (UTC) FILETIME=[68EEB3C0:01CFCC14] X-MC-Unique: 114090910570701701 Content-Type: text/plain; charset=WINDOWS-1252 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id s899x7QR005212 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 Cc: Randy Dunlap Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Henrik Austad Cc: Dario Faggioli Cc: Juri Lelli Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.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..cd8274c 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; + } -- 2.0.4