Daniel Bristot de Oliveira
df8eac8caf
sched/deadline: Throttle a constrained deadline task activated after the deadline ...
During the activation, CBS checks if it can reuse the current task's
runtime and period. If the deadline of the task is in the past, CBS
cannot use the runtime, and so it replenishes the task. This rule
works fine for implicit deadline tasks (deadline == period), and the
CBS was designed for implicit deadline tasks. However, a task with
constrained deadline (deadine < period) might be awakened after the
deadline, but before the next period. In this case, replenishing the
task would allow it to run for runtime / deadline. As in this case
deadline < period, CBS enables a task to run for more than the
runtime / period. In a very loaded system, this can cause a domino
effect, making other tasks miss their deadlines.
To avoid this problem, in the activation of a constrained deadline
task after the deadline but before the next period, throttle the
task and set the replenishing timer to the begin of the next period,
unless it is boosted.
Reproducer:
--------------- %< ---------------
int main (int argc, char **argv)
{
int ret;
int flags = 0;
unsigned long l = 0;
struct timespec ts;
struct sched_attr attr;
memset(&attr, 0, sizeof(attr));
attr.size = sizeof(attr);
attr.sched_policy = SCHED_DEADLINE;
attr.sched_runtime = 2 * 1000 * 1000; /* 2 ms */
attr.sched_deadline = 2 * 1000 * 1000; /* 2 ms */
attr.sched_period = 2 * 1000 * 1000 * 1000; /* 2 s */
ts.tv_sec = 0;
ts.tv_nsec = 2000 * 1000; /* 2 ms */
ret = sched_setattr(0, &attr, flags);
if (ret < 0) {
perror("sched_setattr");
exit(-1);
}
for(;;) {
/* XXX: you may need to adjust the loop */
for (l = 0; l < 150000; l++);
/*
* The ideia is to go to sleep right before the deadline
* and then wake up before the next period to receive
* a new replenishment.
*/
nanosleep(&ts, NULL);
}
exit(0);
}
--------------- >% ---------------
On my box, this reproducer uses almost 50% of the CPU time, which is
obviously wrong for a task with 2/2000 reservation.
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@santannapisa.it>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Romulo Silva de Oliveira <romulo.deoliveira@ufsc.br>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/edf58354e01db46bf42df8d2dd32418833f68c89.1488392936.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-16 09:37:38 +01:00
bpf: convert htab map to hlist_nulls
2017-03-09 13:27:17 -08:00
Merge branch 'for-4.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
2017-03-14 15:11:19 -07:00
config: android-base: enable hardened usercopy and kernel ASLR
2017-02-27 18:43:46 -08:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>
2017-03-02 08:42:34 +01:00
scripts/spelling.txt: add "disble(d)" pattern and fix typo instances
2017-03-09 17:01:09 -08:00
sched/headers: Prepare to move the get_task_struct()/put_task_struct() and related APIs from <linux/sched.h> to <linux/sched/task.h>
2017-03-02 08:42:40 +01:00
Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2017-03-07 14:33:11 -08:00
Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2017-03-03 10:16:38 -08:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h>
2017-03-02 08:42:36 +01:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>
2017-03-02 08:42:34 +01:00
sched/deadline: Throttle a constrained deadline task activated after the deadline
2017-03-16 09:37:38 +01:00
Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2017-03-07 14:45:22 -08:00
scripts/spelling.txt: add "overide" pattern and fix typo instances
2017-03-09 17:01:09 -08:00
sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h>
2017-03-02 08:42:39 +01:00
Merge branch 'stable-4.11' of git://git.infradead.org/users/pcmoore/audit
2017-02-21 13:25:50 -08:00
Merge branch 'stable-4.11' of git://git.infradead.org/users/pcmoore/audit
2017-02-21 13:25:50 -08:00
Merge branch 'stable-4.11' of git://git.infradead.org/users/pcmoore/audit
2017-02-21 13:25:50 -08:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>
2017-03-02 08:42:35 +01:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/coredump.h>
2017-03-02 08:42:28 +01:00
sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h>
2017-03-02 08:42:39 +01:00
userfaultfd: non-cooperative: rollback userfaultfd_exit
2017-03-09 17:01:09 -08:00
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
2017-02-22 10:15:09 -08:00
sched/headers, RCU: Move rcu_copy_process() from <linux/sched/task.h> to kernel/fork.c
2017-03-03 01:43:46 +01:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/mm.h>
2017-03-02 08:42:28 +01:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>
2017-03-02 08:42:34 +01:00
This release has no new tracing features, just clean ups, minor fixes
2017-02-27 13:26:17 -08:00
bpf: make jited programs visible in traces
2017-02-17 13:40:05 -05:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk
2017-02-22 17:33:34 -08:00
kexec, x86/purgatory: Unbreak it and clean it up
2017-03-10 20:55:09 +01:00
kexec, x86/purgatory: Unbreak it and clean it up
2017-03-10 20:55:09 +01:00
sched/headers, vfs/execve: Prepare to move the do_execve*() prototypes from <linux/sched.h> to <linux/binfmts.h>
2017-03-02 08:42:39 +01:00
powerpc updates for 4.11 part 1.
2017-02-22 10:30:38 -08:00
kernel/ksysfs.c: add __ro_after_init to bin_attribute structure
2017-02-24 17:46:56 -08:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>
2017-03-02 08:42:35 +01:00
sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h>
2017-03-02 08:42:39 +01:00
mm, devm_memremap_pages: hold device_hotplug lock over mem_hotplug_{begin, done}
2017-02-24 17:46:53 -08:00
Modules updates for v4.11
2017-02-22 17:08:33 -08:00
kernel/notifier.c: simplify expression
2017-02-24 17:46:56 -08:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>
2017-03-02 08:42:34 +01:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>
2017-03-02 08:42:35 +01:00
sched/headers: Prepare for the reduction of <linux/sched.h>'s signal API dependency
2017-03-02 08:42:37 +01:00
sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h>
2017-03-02 08:42:39 +01:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>
2017-03-02 08:42:35 +01:00
lib/vsprintf.c: remove %Z support
2017-02-27 18:43:47 -08:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h>
2017-03-02 08:42:36 +01:00
sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h>
2017-03-02 08:42:39 +01:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/idle.h>
2017-03-02 08:42:26 +01:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>
2017-03-02 08:42:35 +01:00
stacktrace, lockdep: Fix address, newline ugliness
2017-02-08 08:21:31 +01:00
sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h>
2017-03-02 08:42:39 +01:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/coredump.h>
2017-03-02 08:42:28 +01:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/clock.h>
2017-03-02 08:42:27 +01:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h>
2017-03-02 08:42:35 +01:00
sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h>
2017-03-02 08:42:39 +01:00
ucount: Remove the atomicity from ucount->count
2017-03-06 15:26:37 -06:00
sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h>
2017-03-02 08:42:31 +01:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/user.h>
2017-03-02 08:42:29 +01:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/signal.h>
2017-03-02 08:42:29 +01:00
sched/headers: Prepare to move the task_lock()/unlock() APIs to <linux/sched/task.h>
2017-03-02 08:42:38 +01:00
sched/headers: Remove <linux/rwsem.h> from <linux/sched.h>
2017-03-03 01:45:36 +01:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>
2017-03-02 08:42:34 +01:00
sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h>
2017-03-02 08:42:34 +01:00
workqueue: trigger WARN if queue_delayed_work() is called with NULL @wq
2017-03-06 15:33:42 -05:00
df8eac8caf