[RFC v3] cpuidle : Add support for pseudo-cpuidle driver

[RFC v3] cpuidle : Add support for pseudo-cpuidle driver

[Abhishek Goel]

This option adds support for a testing cpuidle driver, which allows
user to define custom idle states with their respective latencies and
residencies. This is useful for testing the behaviour of governors on
customized set of idle states.

This can be used as of now by specifying a customized set of cpuidle
states in the driver by the user. Will add the capability of this
driver to be used as a module in subsequent patches.

Original idea and discussion for this patch can be found at:
https://lkml.org/lkml/2019/12/17/655

Signed-off-by: Abhishek Goel <huntbag@linux.vnet.ibm.com>
---

 v1->v2 : Changes adapted from reviews of Randy, Dan and Nathan.
	  There was a divergence from expected behaviour of idle loop
	  in v1. That has been fixed.
 v2->v3 : Added simulated latency while entering into idle states.

 drivers/cpuidle/Kconfig        |   9 +
 drivers/cpuidle/Makefile       |   1 +
 drivers/cpuidle/cpuidle-test.c | 289 +++++++++++++++++++++++++++++++++
 3 files changed, 299 insertions(+)
 create mode 100644 drivers/cpuidle/cpuidle-test.c

diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index c0aeedd66f02..1a0f227d61d6 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -71,6 +71,15 @@ config HALTPOLL_CPUIDLE
 	 before halting in the guest (more efficient than polling in the
 	 host via halt_poll_ns for some scenarios).
 
+config TEST_CPUIDLE
+	tristate "cpuidle test driver"
+	default n
+	help
+	  This option enables a testing cpuidle driver, which allows the user
+	  to define custom idle states with their respective latencies & residencies.
+	  This is useful for testing the behaviour of governors on different
+	  sets of idle states.
+
 endif
 
 config ARCH_NEEDS_CPU_IDLE_COUPLED
diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index f07800cbb43f..68ea7dc257b5 100644
--- a/drivers/cpuidle/Makefile
+++ b/drivers/cpuidle/Makefile
@@ -8,6 +8,7 @@ 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
+obj-$(CONFIG_TEST_CPUIDLE)		  += cpuidle-test.o
 
 ##################################################################################
 # ARM SoC drivers
diff --git a/drivers/cpuidle/cpuidle-test.c b/drivers/cpuidle/cpuidle-test.c
new file mode 100644
index 000000000000..17ffce11cafc
--- /dev/null
+++ b/drivers/cpuidle/cpuidle-test.c
@@ -0,0 +1,289 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  cpuidle-test - Test driver for cpuidle.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+#include <linux/cpuidle.h>
+#include <linux/cpu.h>
+#include <linux/module.h>
+#include <linux/sched/idle.h>
+#include <linux/sched/clock.h>
+#include <linux/sched/idle.h>
+
+#define CPUIDLE_STATE_MAX	10
+#define MAX_PARAM_LENGTH	100
+
+static unsigned int nr_states = 4;
+static unsigned int sim_type = 1;
+static char name[MAX_PARAM_LENGTH];
+static char latency_us[MAX_PARAM_LENGTH];
+static char residency_us[MAX_PARAM_LENGTH];
+
+
+module_param(nr_states, uint, 0644);
+module_param(sim_type, uint, 0644);
+module_param_string(name, name, MAX_PARAM_LENGTH, 0644);
+module_param_string(latency_us, latency_us, MAX_PARAM_LENGTH, 0644);
+module_param_string(residency_us, residency_us, MAX_PARAM_LENGTH, 0644);
+
+static struct cpuidle_driver test_cpuidle_driver = {
+	.name		= "test_cpuidle",
+	.owner		= THIS_MODULE,
+};
+
+static struct cpuidle_state *cpuidle_state_table __read_mostly;
+
+static struct cpuidle_device __percpu *test_cpuidle_devices;
+static enum cpuhp_state test_hp_idlestate;
+
+
+static int __cpuidle idle_loop(struct cpuidle_device *dev,
+				struct cpuidle_driver *drv,
+				int index)
+{
+	u64 time_start;
+
+	local_irq_enable();
+
+	time_start = local_clock();
+	/*
+	 * Simulating entry latency into idle state.
+	 */
+	while (local_clock() - time_start < drv->states[index].exit_latency) {
+	}
+
+	if (!current_set_polling_and_test()) {
+		while (!need_resched())
+			cpu_relax();
+	}
+
+	time_start = local_clock();
+	/*
+	 * Simulating exit latency from idle state.
+	 */
+	while (local_clock() - time_start < drv->states[index].exit_latency) {
+	}
+
+	current_clr_polling();
+
+	return index;
+}
+
+	/*
+	 * Defining user specified custome set of idle states.
+	 */
+static struct cpuidle_state cpuidle_states[CPUIDLE_STATE_MAX] = {
+	{	.name = "snooze",
+		.exit_latency = 0,
+		.target_residency = 0,
+		.enter = idle_loop },
+};
+
+static struct cpuidle_state cpuidle_states_ppc[] = {
+	{	.name = "snooze",
+		.exit_latency = 0,
+		.target_residency = 0,
+		.enter = idle_loop },
+	{
+		.name = "stop0",
+		.exit_latency = 2,
+		.target_residency = 20,
+		.enter = idle_loop },
+	{
+		.name = "stop1",
+		.exit_latency = 5,
+		.target_residency = 50,
+		.enter = idle_loop },
+	{
+		.name = "stop2",
+		.exit_latency = 10,
+		.target_residency = 100,
+		.enter = idle_loop },
+};
+
+static struct cpuidle_state cpuidle_states_intel[] = {
+	{	.name = "poll",
+		.exit_latency = 0,
+		.target_residency = 0,
+		.enter = idle_loop },
+	{
+		.name = "c1",
+		.exit_latency = 2,
+		.target_residency = 2,
+		.enter = idle_loop },
+	{
+		.name = "c1e",
+		.exit_latency = 10,
+		.target_residency = 20,
+		.enter = idle_loop },
+	{
+		.name = "c3",
+		.exit_latency = 80,
+		.target_residency = 211,
+		.enter = idle_loop },
+};
+
+static int cpuidle_cpu_online(unsigned int cpu)
+{
+	struct cpuidle_device *dev;
+
+	dev = per_cpu_ptr(test_cpuidle_devices, cpu);
+	if (!dev->registered) {
+		dev->cpu = cpu;
+		if (cpuidle_register_device(dev)) {
+			pr_notice("cpuidle_register_device %d failed!\n", cpu);
+			return -EIO;
+		}
+	}
+
+	return 0;
+}
+
+static int cpuidle_cpu_dead(unsigned int cpu)
+{
+	struct cpuidle_device *dev;
+
+	dev = per_cpu_ptr(test_cpuidle_devices, cpu);
+	if (dev->registered)
+		cpuidle_unregister_device(dev);
+
+	return 0;
+}
+
+static int cpuidle_driver_init(void)
+{
+	int idle_state;
+	struct cpuidle_driver *drv = &test_cpuidle_driver;
+
+	drv->state_count = 0;
+
+	for (idle_state = 0; idle_state < nr_states; ++idle_state) {
+		/* Is the state not enabled? */
+		if (cpuidle_state_table[idle_state].enter == NULL)
+			continue;
+
+		drv->states[drv->state_count] =	/* structure copy */
+			cpuidle_state_table[idle_state];
+
+		drv->state_count += 1;
+	}
+
+	return 0;
+}
+
+static int add_cpuidle_states(void)
+{
+	/* Parse the module param and initialize the idle states here
+	 * in cpuidle_state_table.
+	 */
+	char *this_param;
+	char *input_name = name;
+	char *input_res = residency_us;
+	char *input_lat = latency_us;
+	int index = 1;
+	long temp;
+	int rc;
+
+	switch (sim_type) {
+	case 1:
+		cpuidle_state_table = cpuidle_states_ppc;
+		return 0;
+	case 2:
+		cpuidle_state_table = cpuidle_states_intel;
+		return 0;
+	case 3:
+		break;
+	default:
+		pr_warn("Sim value out of bound\n");
+		break;
+	}
+
+	if (strnlen(input_name, MAX_PARAM_LENGTH)) {
+		while ((this_param = strsep(&input_name, ",")) && index <= nr_states) {
+			strcpy(cpuidle_states[index].name, this_param);
+			cpuidle_states[index].enter = idle_loop;
+			index++;
+		}
+	}
+
+	if (strnlen(input_res, MAX_PARAM_LENGTH)) {
+		index = 1;
+		while ((this_param = strsep(&input_res, ",")) && index <= nr_states) {
+			rc = kstrtol(this_param, 10, &temp);
+			cpuidle_states[index].target_residency = temp;
+			index++;
+		}
+	}
+
+	if (strnlen(input_lat, MAX_PARAM_LENGTH)) {
+		index = 1;
+		while ((this_param = strsep(&input_lat, ",")) && index <= nr_states) {
+			rc = kstrtol(this_param, 10, &temp);
+			cpuidle_states[index].exit_latency = temp;
+			index++;
+		}
+	}
+
+	cpuidle_state_table = cpuidle_states;
+	return nr_states;
+}
+
+static void test_cpuidle_uninit(void)
+{
+	if (test_hp_idlestate)
+		cpuhp_remove_state(test_hp_idlestate);
+	cpuidle_unregister_driver(&test_cpuidle_driver);
+
+	free_percpu(test_cpuidle_devices);
+	test_cpuidle_devices = NULL;
+}
+
+static int __init test_cpuidle_init(void)
+{
+	int retval;
+
+	add_cpuidle_states();
+	cpuidle_driver_init();
+	retval = cpuidle_register(&test_cpuidle_driver, NULL);
+	if (retval) {
+		printk(KERN_DEBUG "Registration of test driver failed.\n");
+		return retval;
+	}
+
+	test_cpuidle_devices = alloc_percpu(struct cpuidle_device);
+	if (test_cpuidle_devices == NULL) {
+		cpuidle_unregister_driver(&test_cpuidle_driver);
+		return -ENOMEM;
+	}
+
+	retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
+					   "cpuidle/powernv:online",
+					   cpuidle_cpu_online,
+					   cpuidle_cpu_dead);
+
+	if (retval < 0) {
+		test_cpuidle_uninit();
+	} else {
+		test_hp_idlestate = retval;
+		retval = 0;
+	}
+
+	return retval;
+}
+
+static void __exit test_cpuidle_exit(void)
+{
+	test_cpuidle_uninit();
+}
+
+module_init(test_cpuidle_init);
+module_exit(test_cpuidle_exit);
+MODULE_DESCRIPTION("Test Cpuidle Driver");
+MODULE_AUTHOR("Abhishek Goel");
+MODULE_LICENSE("GPL");
+
-- 
2.17.1

Re: [RFC v3] cpuidle : Add support for pseudo-cpuidle driver

[kernel test robot]

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Hi Abhishek,

[FYI, it's a private test report for your RFC patch.]
[auto build test WARNING on pm/linux-next]
[also build test WARNING on linus/master linux/master v5.10-rc3 next-20201109]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Abhishek-Goel/cpuidle-Add-support-for-pseudo-cpuidle-driver/20201109-142255
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
config: sh-allmodconfig (attached as .config)
compiler: sh4-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/1fb96577b34f9a7a8ca40bd5f7a8ca712fd2d363
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Abhishek-Goel/cpuidle-Add-support-for-pseudo-cpuidle-driver/20201109-142255
        git checkout 1fb96577b34f9a7a8ca40bd5f7a8ca712fd2d363
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=sh 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   drivers/cpuidle/cpuidle-test.c: In function 'add_cpuidle_states':
>> drivers/cpuidle/cpuidle-test.c:190:6: warning: variable 'rc' set but not used [-Wunused-but-set-variable]
     190 |  int rc;
         |      ^~

vim +/rc +190 drivers/cpuidle/cpuidle-test.c

   178	
   179	static int add_cpuidle_states(void)
   180	{
   181		/* Parse the module param and initialize the idle states here
   182		 * in cpuidle_state_table.
   183		 */
   184		char *this_param;
   185		char *input_name = name;
   186		char *input_res = residency_us;
   187		char *input_lat = latency_us;
   188		int index = 1;
   189		long temp;
 > 190		int rc;
   191	
   192		switch (sim_type) {
   193		case 1:
   194			cpuidle_state_table = cpuidle_states_ppc;
   195			return 0;
   196		case 2:
   197			cpuidle_state_table = cpuidle_states_intel;
   198			return 0;
   199		case 3:
   200			break;
   201		default:
   202			pr_warn("Sim value out of bound\n");
   203			break;
   204		}
   205	
   206		if (strnlen(input_name, MAX_PARAM_LENGTH)) {
   207			while ((this_param = strsep(&input_name, ",")) && index <= nr_states) {
   208				strcpy(cpuidle_states[index].name, this_param);
   209				cpuidle_states[index].enter = idle_loop;
   210				index++;
   211			}
   212		}
   213	
   214		if (strnlen(input_res, MAX_PARAM_LENGTH)) {
   215			index = 1;
   216			while ((this_param = strsep(&input_res, ",")) && index <= nr_states) {
   217				rc = kstrtol(this_param, 10, &temp);
   218				cpuidle_states[index].target_residency = temp;
   219				index++;
   220			}
   221		}
   222	
   223		if (strnlen(input_lat, MAX_PARAM_LENGTH)) {
   224			index = 1;
   225			while ((this_param = strsep(&input_lat, ",")) && index <= nr_states) {
   226				rc = kstrtol(this_param, 10, &temp);
   227				cpuidle_states[index].exit_latency = temp;
   228				index++;
   229			}
   230		}
   231	
   232		cpuidle_state_table = cpuidle_states;
   233		return nr_states;
   234	}
   235	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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