[patch 1/5] drivers/cpuidle: add cpuidle-haltpoll driver

Marcelo Tosatti
2019-06-13T22:55:18Z

Add a cpuidle driver that calls the architecture default_idle routine.

To be used in conjunction with the haltpoll governor.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

---
arch/x86/kernel/process.c | 2 -
drivers/cpuidle/Kconfig | 9 +++++
drivers/cpuidle/Makefile | 1
drivers/cpuidle/cpuidle-haltpoll.c | 65 +++++++++++++++++++++++++++++++++++++
4 files changed, 76 insertions(+), 1 deletion(-)

Index: linux-2.6.git/arch/x86/kernel/process.c
===================================================================
--- linux-2.6.git.orig/arch/x86/kernel/process.c 2019-06-13 16:19:27.877064340 -0400
+++ linux-2.6.git/arch/x86/kernel/process.c 2019-06-13 16:19:48.795544892 -0400
@@ -580,7 +580,7 @@
safe_halt();
trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
}
-#ifdef CONFIG_APM_MODULE
+#if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE)
EXPORT_SYMBOL(default_idle);
#endif

Index: linux-2.6.git/drivers/cpuidle/Kconfig
===================================================================
--- linux-2.6.git.orig/drivers/cpuidle/Kconfig 2019-06-13 16:19:27.878064316 -0400
+++ linux-2.6.git/drivers/cpuidle/Kconfig 2019-06-13 18:41:40.599912671 -0400
@@ -51,6 +51,15 @@
source "drivers/cpuidle/Kconfig.powerpc"
endmenu

+config HALTPOLL_CPUIDLE
+ tristate "Halt poll cpuidle driver"
+ depends on X86
+ default y
+ help
+ This option enables halt poll cpuidle driver, which allows to poll
+ before halting in the guest (more efficient than polling in the
+ host via halt_poll_ns for some scenarios).
+
endif

config ARCH_NEEDS_CPU_IDLE_COUPLED
Index: linux-2.6.git/drivers/cpuidle/Makefile
===================================================================
--- linux-2.6.git.orig/drivers/cpuidle/Makefile 2019-06-13 16:19:27.878064316 -0400
+++ linux-2.6.git/drivers/cpuidle/Makefile 2019-06-13 16:19:48.796544867 -0400
@@ -7,6 +7,7 @@
obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o
obj-$(CONFIG_DT_IDLE_STATES) += dt_idle_states.o
obj-$(CONFIG_ARCH_HAS_CPU_RELAX) += poll_state.o
+obj-$(CONFIG_HALTPOLL_CPUIDLE) += cpuidle-haltpoll.o

##################################################################################
# ARM SoC drivers
Index: linux-2.6.git/drivers/cpuidle/cpuidle-haltpoll.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.git/drivers/cpuidle/cpuidle-haltpoll.c 2019-06-13 18:41:39.305933413 -0400
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * cpuidle driver for haltpoll governor.
+ *
+ * Copyright 2019 Red Hat, Inc. and/or its affiliates.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ *
+ * Authors: Marcelo Tosatti <mtosatti@redhat.com>
+ */
+
+#include <linux/init.h>
+#include <linux/cpuidle.h>
+#include <linux/module.h>
+#include <linux/sched/idle.h>
+
+static int default_enter_idle(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
+{
+ if (current_clr_polling_and_test()) {
+ local_irq_enable();
+ return index;
+ }
+ default_idle();
+ return index;
+}
+
+static struct cpuidle_driver haltpoll_driver = {
+ .name = "haltpoll",
+ .owner = THIS_MODULE,
+ .states = {
+ { /* entry 0 is for polling */ },
+ {
+ .enter = default_enter_idle,
+ .exit_latency = 0,
+ .target_residency = 0,
+ .power_usage = -1,
+ .name = "haltpoll idle",
+ .desc = "default architecture idle",
+ },
+ },
+ .safe_state_index = 0,
+ .state_count = 2,
+};
+
+static int __init haltpoll_init(void)
+{
+ struct cpuidle_driver *drv = &haltpoll_driver;
+
+ cpuidle_poll_state_init(drv);
+
+ return cpuidle_register(&haltpoll_driver, NULL);
+}
+
+static void __exit haltpoll_exit(void)
+{
+ cpuidle_unregister(&haltpoll_driver);
+}
+
+module_init(haltpoll_init);
+module_exit(haltpoll_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Marcelo Tosatti <mtosatti@redhat.com>");
+