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Commit 92205c23 authored by Steven Rostedt's avatar Steven Rostedt Committed by Thomas Gleixner
Browse files

ftrace: user raw_spin_lock in tracing 



Lock debugging enabled cause huge performance problems for tracing. Having
the lock verification happening for every function that is called
because mcount calls spin_lock can cripple the system.

This patch converts the spin_locks used by ftrace into raw_spin_locks.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent c5f888ca

kernel/trace/trace.c

+30 −21
Original line number Diff line number Diff line
@@ -133,7 +133,8 @@ static const char *trace_options[] = { 
	NULL

};



static DEFINE_SPINLOCK(ftrace_max_lock);

static raw_spinlock_t ftrace_max_lock =

	(raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;



/*

 * Copy the new maximum trace into the separate maximum-trace
@@ -335,7 +336,7 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu) 
	int i;



	WARN_ON_ONCE(!irqs_disabled());

	spin_lock(&ftrace_max_lock);

	__raw_spin_lock(&ftrace_max_lock);

	/* clear out all the previous traces */

	for_each_possible_cpu(i) {

		data = tr->data[i];
@@ -344,7 +345,7 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu) 
	}



	__update_max_tr(tr, tsk, cpu);

	spin_unlock(&ftrace_max_lock);

	__raw_spin_unlock(&ftrace_max_lock);

}



/**
@@ -360,7 +361,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu) 
	int i;



	WARN_ON_ONCE(!irqs_disabled());

	spin_lock(&ftrace_max_lock);

	__raw_spin_lock(&ftrace_max_lock);

	for_each_possible_cpu(i)

		tracing_reset(max_tr.data[i]);
@@ -368,7 +369,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu) 
	tracing_reset(data);



	__update_max_tr(tr, tsk, cpu);

	spin_unlock(&ftrace_max_lock);

	__raw_spin_unlock(&ftrace_max_lock);

}



int register_tracer(struct tracer *type)
@@ -652,13 +653,15 @@ trace_function(struct trace_array *tr, struct trace_array_cpu *data, 
	struct trace_entry *entry;

	unsigned long irq_flags;



	spin_lock_irqsave(&data->lock, irq_flags);

	raw_local_irq_save(irq_flags);

	__raw_spin_lock(&data->lock);

	entry			= tracing_get_trace_entry(tr, data);

	tracing_generic_entry_update(entry, flags);

	entry->type		= TRACE_FN;

	entry->fn.ip		= ip;

	entry->fn.parent_ip	= parent_ip;

	spin_unlock_irqrestore(&data->lock, irq_flags);

	__raw_spin_unlock(&data->lock);

	raw_local_irq_restore(irq_flags);

}



void
@@ -678,14 +681,16 @@ __trace_special(void *__tr, void *__data, 
	struct trace_entry *entry;

	unsigned long irq_flags;



	spin_lock_irqsave(&data->lock, irq_flags);

	raw_local_irq_save(irq_flags);

	__raw_spin_lock(&data->lock);

	entry			= tracing_get_trace_entry(tr, data);

	tracing_generic_entry_update(entry, 0);

	entry->type		= TRACE_SPECIAL;

	entry->special.arg1	= arg1;

	entry->special.arg2	= arg2;

	entry->special.arg3	= arg3;

	spin_unlock_irqrestore(&data->lock, irq_flags);

	__raw_spin_unlock(&data->lock);

	raw_local_irq_restore(irq_flags);



	trace_wake_up();

}
@@ -725,7 +730,8 @@ tracing_sched_switch_trace(struct trace_array *tr, 
	struct trace_entry *entry;

	unsigned long irq_flags;



	spin_lock_irqsave(&data->lock, irq_flags);

	raw_local_irq_save(irq_flags);

	__raw_spin_lock(&data->lock);

	entry			= tracing_get_trace_entry(tr, data);

	tracing_generic_entry_update(entry, flags);

	entry->type		= TRACE_CTX;
@@ -736,7 +742,8 @@ tracing_sched_switch_trace(struct trace_array *tr, 
	entry->ctx.next_prio	= next->prio;

	entry->ctx.next_state	= next->state;

	__trace_stack(tr, data, flags, 4);

	spin_unlock_irqrestore(&data->lock, irq_flags);

	__raw_spin_unlock(&data->lock);

	raw_local_irq_restore(irq_flags);

}



void
@@ -749,7 +756,8 @@ tracing_sched_wakeup_trace(struct trace_array *tr, 
	struct trace_entry *entry;

	unsigned long irq_flags;



	spin_lock_irqsave(&data->lock, irq_flags);

	raw_local_irq_save(irq_flags);

	__raw_spin_lock(&data->lock);

	entry			= tracing_get_trace_entry(tr, data);

	tracing_generic_entry_update(entry, flags);

	entry->type		= TRACE_WAKE;
@@ -760,7 +768,8 @@ tracing_sched_wakeup_trace(struct trace_array *tr, 
	entry->ctx.next_prio	= wakee->prio;

	entry->ctx.next_state	= wakee->state;

	__trace_stack(tr, data, flags, 5);

	spin_unlock_irqrestore(&data->lock, irq_flags);

	__raw_spin_unlock(&data->lock);

	raw_local_irq_restore(irq_flags);



	trace_wake_up();

}
@@ -1824,7 +1833,8 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf, 
	if (err)

		goto err_unlock;



	spin_lock_irq(&ftrace_max_lock);

	raw_local_irq_disable();

	__raw_spin_lock(&ftrace_max_lock);

	for_each_possible_cpu(cpu) {

		/*

		 * Increase/decrease the disabled counter if we are
@@ -1839,7 +1849,8 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf, 
			atomic_dec(&global_trace.data[cpu]->disabled);

		}

	}

	spin_unlock_irq(&ftrace_max_lock);

	__raw_spin_unlock(&ftrace_max_lock);

	raw_local_irq_enable();



	tracing_cpumask = tracing_cpumask_new;
@@ -2299,7 +2310,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, 


	for_each_cpu_mask(cpu, mask) {

		data = iter->tr->data[cpu];

		spin_lock(&data->lock);

		__raw_spin_lock(&data->lock);

	}



	while (find_next_entry_inc(iter) != NULL) {
@@ -2320,7 +2331,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, 


	for_each_cpu_mask(cpu, mask) {

		data = iter->tr->data[cpu];

		spin_unlock(&data->lock);

		__raw_spin_unlock(&data->lock);

	}



	for_each_cpu_mask(cpu, mask) {
@@ -2538,8 +2549,7 @@ static int trace_alloc_page(void) 
	/* Now that we successfully allocate a page per CPU, add them */

	for_each_possible_cpu(i) {

		data = global_trace.data[i];

		spin_lock_init(&data->lock);

		lockdep_set_class(&data->lock, &data->lock_key);

		data->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;

		page = list_entry(pages.next, struct page, lru);

		list_del_init(&page->lru);

		list_add_tail(&page->lru, &data->trace_pages);
@@ -2547,8 +2557,7 @@ static int trace_alloc_page(void) 


#ifdef CONFIG_TRACER_MAX_TRACE

		data = max_tr.data[i];

		spin_lock_init(&data->lock);

		lockdep_set_class(&data->lock, &data->lock_key);

		data->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;

		page = list_entry(pages.next, struct page, lru);

		list_del_init(&page->lru);

		list_add_tail(&page->lru, &data->trace_pages);

kernel/trace/trace.h

+1 −1
Original line number Diff line number Diff line
@@ -76,7 +76,7 @@ struct trace_entry { 
struct trace_array_cpu {

	struct list_head	trace_pages;

	atomic_t		disabled;

	spinlock_t		lock;

	raw_spinlock_t		lock;

	struct lock_class_key	lock_key;



	/* these fields get copied into max-trace: */