defconfig: 8953: Move RCU callbacks processing to kernel threads
Under high load situations RCU callback processing adds a
significant workload to softirq. This may result in CPU
starvation for other time critical entities, waiting to run
in softirq context. This patch eanbles the kernel option
which allows to perform RCU callback processing in separate
kernel threads and thus reducing the softriq workload a lot.
Change-Id: I2f8baee5d315708c76d33490a4be1792fb3fb680
Signed-off-by: Imran Khan <kimran@codeaurora.org>
diff --git a/arch/arm/configs/msmcortex-perf_defconfig b/arch/arm/configs/msmcortex-perf_defconfig
index fc5a36d..00be085 100644
--- a/arch/arm/configs/msmcortex-perf_defconfig
+++ b/arch/arm/configs/msmcortex-perf_defconfig
@@ -5,6 +5,8 @@
CONFIG_HIGH_RES_TIMERS=y
CONFIG_IRQ_TIME_ACCOUNTING=y
CONFIG_RCU_FAST_NO_HZ=y
+CONFIG_RCU_NOCB_CPU=y
+CONFIG_RCU_NOCB_CPU_ALL=y
CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y
CONFIG_CGROUPS=y
diff --git a/arch/arm/configs/msmcortex_defconfig b/arch/arm/configs/msmcortex_defconfig
index 0c5bfd8..191b6d0 100644
--- a/arch/arm/configs/msmcortex_defconfig
+++ b/arch/arm/configs/msmcortex_defconfig
@@ -3,6 +3,9 @@
CONFIG_NO_HZ=y
CONFIG_HIGH_RES_TIMERS=y
CONFIG_IRQ_TIME_ACCOUNTING=y
+CONFIG_RCU_FAST_NO_HZ=y
+CONFIG_RCU_NOCB_CPU=y
+CONFIG_RCU_NOCB_CPU_ALL=y
CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y
CONFIG_CGROUPS=y
diff --git a/arch/arm64/configs/msmcortex-perf_defconfig b/arch/arm64/configs/msmcortex-perf_defconfig
index ee0c3c6..960e0e0 100644
--- a/arch/arm64/configs/msmcortex-perf_defconfig
+++ b/arch/arm64/configs/msmcortex-perf_defconfig
@@ -4,6 +4,8 @@
CONFIG_HIGH_RES_TIMERS=y
CONFIG_IRQ_TIME_ACCOUNTING=y
CONFIG_RCU_FAST_NO_HZ=y
+CONFIG_RCU_NOCB_CPU=y
+CONFIG_RCU_NOCB_CPU_ALL=y
CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y
CONFIG_CGROUPS=y
diff --git a/arch/arm64/configs/msmcortex_defconfig b/arch/arm64/configs/msmcortex_defconfig
index d8f3659..30d53ef 100644
--- a/arch/arm64/configs/msmcortex_defconfig
+++ b/arch/arm64/configs/msmcortex_defconfig
@@ -3,6 +3,8 @@
CONFIG_HIGH_RES_TIMERS=y
CONFIG_IRQ_TIME_ACCOUNTING=y
CONFIG_RCU_FAST_NO_HZ=y
+CONFIG_RCU_NOCB_CPU=y
+CONFIG_RCU_NOCB_CPU_ALL=y
CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y
CONFIG_CGROUPS=y
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 80242f0..c303301 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1601,6 +1601,7 @@
extern int tick_nohz_active;
+#ifndef CONFIG_RCU_NOCB_CPU_ALL
/*
* Does the specified flavor of RCU have non-lazy callbacks pending on
* the specified CPU? Both RCU flavor and CPU are specified by the
@@ -1642,7 +1643,7 @@
__rcu_cpu_has_nonlazy_callbacks(&per_cpu(rcu_bh_data, cpu)) ||
rcu_preempt_cpu_has_nonlazy_callbacks(cpu);
}
-
+#endif
/*
* Allow the CPU to enter dyntick-idle mode if either: (1) There are no
* callbacks on this CPU, (2) this CPU has not yet attempted to enter
