rcu: Add boosting to TREE_PREEMPT_RCU tracing (0ea1f2eb) · Commits · e / devices / android_kernel_samsung_universal8895

kernel/rcutree.h

+19 −0

Original line number	Original line	Diff line number	Diff line
	@@ -152,6 +152,25 @@ struct rcu_node {
	wait_queue_head_t boost_wq;		wait_queue_head_t boost_wq;
	/* Wait queue on which to park the boost */		/* Wait queue on which to park the boost */
	/* kthread. */		/* kthread. */
			unsigned long n_tasks_boosted;
			/* Total number of tasks boosted. */
			unsigned long n_exp_boosts;
			/* Number of tasks boosted for expedited GP. */
			unsigned long n_normal_boosts;
			/* Number of tasks boosted for normal GP. */
			unsigned long n_balk_blkd_tasks;
			/* Refused to boost: no blocked tasks. */
			unsigned long n_balk_exp_gp_tasks;
			/* Refused to boost: nothing blocking GP. */
			unsigned long n_balk_boost_tasks;
			/* Refused to boost: already boosting. */
			unsigned long n_balk_notblocked;
			/* Refused to boost: RCU RS CS still running. */
			unsigned long n_balk_notyet;
			/* Refused to boost: not yet time. */
			unsigned long n_balk_nos;
			/* Refused to boost: not sure why, though. */
			/* This can happen due to race conditions. */
	#endif /* #ifdef CONFIG_RCU_BOOST */		#endif /* #ifdef CONFIG_RCU_BOOST */
	struct task_struct *node_kthread_task;		struct task_struct *node_kthread_task;
	/* kthread that takes care of this rcu_node */		/* kthread that takes care of this rcu_node */

kernel/rcutree_plugin.h

+38 −4

Original line number	Original line	Diff line number	Diff line
	@@ -1073,6 +1073,33 @@ static void __init __rcu_init_preempt(void)

	#include "rtmutex_common.h"		#include "rtmutex_common.h"

			#ifdef CONFIG_RCU_TRACE

			static void rcu_initiate_boost_trace(struct rcu_node *rnp)
			{
			if (list_empty(&rnp->blkd_tasks))
			rnp->n_balk_blkd_tasks++;
			else if (rnp->exp_tasks == NULL && rnp->gp_tasks == NULL)
			rnp->n_balk_exp_gp_tasks++;
			else if (rnp->gp_tasks != NULL && rnp->boost_tasks != NULL)
			rnp->n_balk_boost_tasks++;
			else if (rnp->gp_tasks != NULL && rnp->qsmask != 0)
			rnp->n_balk_notblocked++;
			else if (rnp->gp_tasks != NULL &&
			ULONG_CMP_GE(jiffies, rnp->boost_time))
			rnp->n_balk_notyet++;
			else
			rnp->n_balk_nos++;
			}

			#else /* #ifdef CONFIG_RCU_TRACE */

			static void rcu_initiate_boost_trace(struct rcu_node *rnp)
			{
			}

			#endif /* #else #ifdef CONFIG_RCU_TRACE */

	/*		/*
	* Carry out RCU priority boosting on the task indicated by ->exp_tasks		* Carry out RCU priority boosting on the task indicated by ->exp_tasks
	* or ->boost_tasks, advancing the pointer to the next task in the		* or ->boost_tasks, advancing the pointer to the next task in the
	@@ -1108,10 +1135,14 @@ static int rcu_boost(struct rcu_node *rnp)
	* expedited grace period must boost all blocked tasks, including		* expedited grace period must boost all blocked tasks, including
	* those blocking the pre-existing normal grace period.		* those blocking the pre-existing normal grace period.
	*/		*/
	if (rnp->exp_tasks != NULL)		if (rnp->exp_tasks != NULL) {
	tb = rnp->exp_tasks;		tb = rnp->exp_tasks;
	else		rnp->n_exp_boosts++;
			} else {
	tb = rnp->boost_tasks;		tb = rnp->boost_tasks;
			rnp->n_normal_boosts++;
			}
			rnp->n_tasks_boosted++;

	/*		/*
	* We boost task t by manufacturing an rt_mutex that appears to		* We boost task t by manufacturing an rt_mutex that appears to
	@@ -1197,8 +1228,10 @@ static void rcu_initiate_boost(struct rcu_node *rnp)
	{		{
	struct task_struct *t;		struct task_struct *t;

	if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL)		if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL) {
			rnp->n_balk_exp_gp_tasks++;
	return;		return;
			}
	if (rnp->exp_tasks != NULL \|\|		if (rnp->exp_tasks != NULL \|\|
	(rnp->gp_tasks != NULL &&		(rnp->gp_tasks != NULL &&
	rnp->boost_tasks == NULL &&		rnp->boost_tasks == NULL &&
	@@ -1209,7 +1242,8 @@ static void rcu_initiate_boost(struct rcu_node *rnp)
	t = rnp->boost_kthread_task;		t = rnp->boost_kthread_task;
	if (t != NULL)		if (t != NULL)
	wake_up_process(t);		wake_up_process(t);
	}		} else
			rcu_initiate_boost_trace(rnp);
	}		}

	/*		/*

kernel/rcutree_trace.c

+68 −0

Original line number	Original line	Diff line number	Diff line
	@@ -157,6 +157,71 @@ static const struct file_operations rcudata_csv_fops = {
	.release = single_release,		.release = single_release,
	};		};

			#ifdef CONFIG_RCU_BOOST

			static void print_one_rcu_node_boost(struct seq_file m, struct rcu_node rnp)
			{
			seq_printf(m, "%d:%d tasks=%c%c%c%c ntb=%lu neb=%lu nnb=%lu "
			"j=%04x bt=%04x\n",
			rnp->grplo, rnp->grphi,
			"T."[list_empty(&rnp->blkd_tasks)],
			"N."[!rnp->gp_tasks],
			"E."[!rnp->exp_tasks],
			"B."[!rnp->boost_tasks],
			rnp->n_tasks_boosted, rnp->n_exp_boosts,
			rnp->n_normal_boosts,
			(int)(jiffies & 0xffff),
			(int)(rnp->boost_time & 0xffff));
			seq_printf(m, "%s: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
			" balk",
			rnp->n_balk_blkd_tasks,
			rnp->n_balk_exp_gp_tasks,
			rnp->n_balk_boost_tasks,
			rnp->n_balk_notblocked,
			rnp->n_balk_notyet,
			rnp->n_balk_nos);
			}

			static int show_rcu_node_boost(struct seq_file m, void unused)
			{
			struct rcu_node *rnp;

			rcu_for_each_leaf_node(&rcu_preempt_state, rnp)
			print_one_rcu_node_boost(m, rnp);
			return 0;
			}

			static int rcu_node_boost_open(struct inode inode, struct file file)
			{
			return single_open(file, show_rcu_node_boost, NULL);
			}

			static const struct file_operations rcu_node_boost_fops = {
			.owner = THIS_MODULE,
			.open = rcu_node_boost_open,
			.read = seq_read,
			.llseek = seq_lseek,
			.release = single_release,
			};

			/*
			* Create the rcuboost debugfs entry. Standard error return.
			*/
			static int rcu_boost_trace_create_file(struct dentry *rcudir)
			{
			return !debugfs_create_file("rcuboost", 0444, rcudir, NULL,
			&rcu_node_boost_fops);
			}

			#else /* #ifdef CONFIG_RCU_BOOST */

			static int rcu_boost_trace_create_file(struct dentry *rcudir)
			{
			return 0; /* There cannot be an error if we didn't create it! */
			}

			#endif /* #else #ifdef CONFIG_RCU_BOOST */

	static void print_one_rcu_state(struct seq_file m, struct rcu_state rsp)		static void print_one_rcu_state(struct seq_file m, struct rcu_state rsp)
	{		{
	unsigned long gpnum;		unsigned long gpnum;
	@@ -315,6 +380,9 @@ static int __init rcutree_trace_init(void)
	if (!retval)		if (!retval)
	goto free_out;		goto free_out;

			if (rcu_boost_trace_create_file(rcudir))
			goto free_out;

	retval = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops);		retval = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops);
	if (!retval)		if (!retval)
	goto free_out;		goto free_out;