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-rw-r--r--debian/patches-rt/0218-sched-Disable-TTWU_QUEUE-on-RT.patch38
1 files changed, 38 insertions, 0 deletions
diff --git a/debian/patches-rt/0218-sched-Disable-TTWU_QUEUE-on-RT.patch b/debian/patches-rt/0218-sched-Disable-TTWU_QUEUE-on-RT.patch
new file mode 100644
index 000000000..77eb3b029
--- /dev/null
+++ b/debian/patches-rt/0218-sched-Disable-TTWU_QUEUE-on-RT.patch
@@ -0,0 +1,38 @@
+From 5b867d72795af288909e6370aabef927a70c8d78 Mon Sep 17 00:00:00 2001
+From: Thomas Gleixner <tglx@linutronix.de>
+Date: Tue, 13 Sep 2011 16:42:35 +0200
+Subject: [PATCH 218/323] sched: Disable TTWU_QUEUE on RT
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz
+
+The queued remote wakeup mechanism can introduce rather large
+latencies if the number of migrated tasks is high. Disable it for RT.
+
+Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+---
+ kernel/sched/features.h | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/kernel/sched/features.h b/kernel/sched/features.h
+index f1bf5e12d889..402fd37fb340 100644
+--- a/kernel/sched/features.h
++++ b/kernel/sched/features.h
+@@ -45,11 +45,16 @@ SCHED_FEAT(DOUBLE_TICK, false)
+ */
+ SCHED_FEAT(NONTASK_CAPACITY, true)
+
++#ifdef CONFIG_PREEMPT_RT
++SCHED_FEAT(TTWU_QUEUE, false)
++#else
++
+ /*
+ * Queue remote wakeups on the target CPU and process them
+ * using the scheduler IPI. Reduces rq->lock contention/bounces.
+ */
+ SCHED_FEAT(TTWU_QUEUE, true)
++#endif
+
+ /*
+ * When doing wakeups, attempt to limit superfluous scans of the LLC domain.
+--
+2.43.0
+