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authorJuri Lelli <juri.lelli@arm.com>2014-10-07 09:52:11 +0100
committerIngo Molnar <mingo@kernel.org>2014-10-28 10:48:00 +0100
commitf82f80426f7afcf55953924e71555984a4bd6ce6 (patch)
tree3a3e15c85f04c11d8f9bc0708b4c8ca439d3431b /kernel/sched
parent7f51412a415d87ea8598d14722fb31e4f5701257 (diff)
downloadblackbird-op-linux-f82f80426f7afcf55953924e71555984a4bd6ce6.tar.gz
blackbird-op-linux-f82f80426f7afcf55953924e71555984a4bd6ce6.zip
sched/deadline: Ensure that updates to exclusive cpusets don't break AC
How we deal with updates to exclusive cpusets is currently broken. As an example, suppose we have an exclusive cpuset composed of two cpus: A[cpu0,cpu1]. We can assign SCHED_DEADLINE task to it up to the allowed bandwidth. If we want now to modify cpusetA's cpumask, we have to check that removing a cpu's amount of bandwidth doesn't break AC guarantees. This thing isn't checked in the current code. This patch fixes the problem above, denying an update if the new cpumask won't have enough bandwidth for SCHED_DEADLINE tasks that are currently active. Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Li Zefan <lizefan@huawei.com> Cc: cgroups@vger.kernel.org Link: http://lkml.kernel.org/r/5433E6AF.5080105@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/core.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9993feeb8b10..0456a55fc27f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4650,6 +4650,25 @@ void init_idle(struct task_struct *idle, int cpu)
#endif
}
+int cpuset_cpumask_can_shrink(const struct cpumask *cur,
+ const struct cpumask *trial)
+{
+ int ret = 1, trial_cpus;
+ struct dl_bw *cur_dl_b;
+ unsigned long flags;
+
+ cur_dl_b = dl_bw_of(cpumask_any(cur));
+ trial_cpus = cpumask_weight(trial);
+
+ raw_spin_lock_irqsave(&cur_dl_b->lock, flags);
+ if (cur_dl_b->bw != -1 &&
+ cur_dl_b->bw * trial_cpus < cur_dl_b->total_bw)
+ ret = 0;
+ raw_spin_unlock_irqrestore(&cur_dl_b->lock, flags);
+
+ return ret;
+}
+
int task_can_attach(struct task_struct *p,
const struct cpumask *cs_cpus_allowed)
{
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