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Commit 9745512c authored by Arjan van de Ven's avatar Arjan van de Ven Committed by Ingo Molnar
Browse files

sched: latencytop support 



LatencyTOP kernel infrastructure; it measures latencies in the
scheduler and tracks it system wide and per process.

Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 326587b8

arch/x86/kernel/stacktrace.c

+27 −0
Original line number Diff line number Diff line
@@ -33,6 +33,19 @@ static void save_stack_address(void *data, unsigned long addr) 
		trace->entries[trace->nr_entries++] = addr;

}



static void save_stack_address_nosched(void *data, unsigned long addr)

{

	struct stack_trace *trace = (struct stack_trace *)data;

	if (in_sched_functions(addr))

		return;

	if (trace->skip > 0) {

		trace->skip--;

		return;

	}

	if (trace->nr_entries < trace->max_entries)

		trace->entries[trace->nr_entries++] = addr;

}



static const struct stacktrace_ops save_stack_ops = {

	.warning = save_stack_warning,

	.warning_symbol = save_stack_warning_symbol,
@@ -40,6 +53,13 @@ static const struct stacktrace_ops save_stack_ops = { 
	.address = save_stack_address,

};



static const struct stacktrace_ops save_stack_ops_nosched = {

	.warning = save_stack_warning,

	.warning_symbol = save_stack_warning_symbol,

	.stack = save_stack_stack,

	.address = save_stack_address_nosched,

};



/*

 * Save stack-backtrace addresses into a stack_trace buffer.

 */
@@ -50,3 +70,10 @@ void save_stack_trace(struct stack_trace *trace) 
		trace->entries[trace->nr_entries++] = ULONG_MAX;

}

EXPORT_SYMBOL(save_stack_trace);



void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)

{

	dump_trace(tsk, NULL, NULL, &save_stack_ops_nosched, trace);

	if (trace->nr_entries < trace->max_entries)

		trace->entries[trace->nr_entries++] = ULONG_MAX;

}

fs/proc/base.c

+78 −0
Original line number Diff line number Diff line
@@ -310,6 +310,77 @@ static int proc_pid_schedstat(struct task_struct *task, char *buffer) 
}

#endif



#ifdef CONFIG_LATENCYTOP

static int lstats_show_proc(struct seq_file *m, void *v)

{

	int i;

	struct task_struct *task = m->private;

	seq_puts(m, "Latency Top version : v0.1\n");



	for (i = 0; i < 32; i++) {

		if (task->latency_record[i].backtrace[0]) {

			int q;

			seq_printf(m, "%i %li %li ",

				task->latency_record[i].count,

				task->latency_record[i].time,

				task->latency_record[i].max);

			for (q = 0; q < LT_BACKTRACEDEPTH; q++) {

				char sym[KSYM_NAME_LEN];

				char *c;

				if (!task->latency_record[i].backtrace[q])

					break;

				if (task->latency_record[i].backtrace[q] == ULONG_MAX)

					break;

				sprint_symbol(sym, task->latency_record[i].backtrace[q]);

				c = strchr(sym, '+');

				if (c)

					*c = 0;

				seq_printf(m, "%s ", sym);

			}

			seq_printf(m, "\n");

		}



	}

	return 0;

}



static int lstats_open(struct inode *inode, struct file *file)

{

	int ret;

	struct seq_file *m;

	struct task_struct *task = get_proc_task(inode);



	ret = single_open(file, lstats_show_proc, NULL);

	if (!ret) {

		m = file->private_data;

		m->private = task;

	}

	return ret;

}



static ssize_t lstats_write(struct file *file, const char __user *buf,

			    size_t count, loff_t *offs)

{

	struct seq_file *m;

	struct task_struct *task;



	m = file->private_data;

	task = m->private;

	clear_all_latency_tracing(task);



	return count;

}



static const struct file_operations proc_lstats_operations = {

	.open		= lstats_open,

	.read		= seq_read,

	.write		= lstats_write,

	.llseek		= seq_lseek,

	.release	= single_release,

};



#endif



/* The badness from the OOM killer */

unsigned long badness(struct task_struct *p, unsigned long uptime);

static int proc_oom_score(struct task_struct *task, char *buffer)
@@ -1020,6 +1091,7 @@ static const struct file_operations proc_fault_inject_operations = { 
};

#endif





#ifdef CONFIG_SCHED_DEBUG

/*

 * Print out various scheduling related per-task fields:
@@ -2230,6 +2302,9 @@ static const struct pid_entry tgid_base_stuff[] = { 
#ifdef CONFIG_SCHEDSTATS

	INF("schedstat",  S_IRUGO, pid_schedstat),

#endif

#ifdef CONFIG_LATENCYTOP

	REG("latency",  S_IRUGO, lstats),

#endif

#ifdef CONFIG_PROC_PID_CPUSET

	REG("cpuset",     S_IRUGO, cpuset),

#endif
@@ -2555,6 +2630,9 @@ static const struct pid_entry tid_base_stuff[] = { 
#ifdef CONFIG_SCHEDSTATS

	INF("schedstat", S_IRUGO, pid_schedstat),

#endif

#ifdef CONFIG_LATENCYTOP

	REG("latency",  S_IRUGO, lstats),

#endif

#ifdef CONFIG_PROC_PID_CPUSET

	REG("cpuset",    S_IRUGO, cpuset),

#endif

include/linux/latencytop.h

0 → 100644
+44 −0
Original line number Diff line number Diff line 
/*

 * latencytop.h: Infrastructure for displaying latency

 *

 * (C) Copyright 2008 Intel Corporation

 * Author: Arjan van de Ven <arjan@linux.intel.com>

 *

 */



#ifndef _INCLUDE_GUARD_LATENCYTOP_H_

#define _INCLUDE_GUARD_LATENCYTOP_H_



#ifdef CONFIG_LATENCYTOP



#define LT_SAVECOUNT		32

#define LT_BACKTRACEDEPTH	12



struct latency_record {

	unsigned long	backtrace[LT_BACKTRACEDEPTH];

	unsigned int	count;

	unsigned long	time;

	unsigned long	max;

};





struct task_struct;



void account_scheduler_latency(struct task_struct *task, int usecs, int inter);



void clear_all_latency_tracing(struct task_struct *p);



#else



static inline void

account_scheduler_latency(struct task_struct *task, int usecs, int inter)

{

}



static inline void clear_all_latency_tracing(struct task_struct *p)

{

}



#endif



#endif

include/linux/sched.h

+5 −0
Original line number Diff line number Diff line
@@ -88,6 +88,7 @@ struct sched_param { 
#include <linux/hrtimer.h>

#include <linux/task_io_accounting.h>

#include <linux/kobject.h>

#include <linux/latencytop.h>



#include <asm/processor.h>
@@ -1220,6 +1221,10 @@ struct task_struct { 
	int make_it_fail;

#endif

	struct prop_local_single dirties;

#ifdef CONFIG_LATENCYTOP

	int latency_record_count;

	struct latency_record latency_record[LT_SAVECOUNT];

#endif

};



/*

include/linux/stacktrace.h

+3 −0
Original line number Diff line number Diff line
@@ -9,10 +9,13 @@ struct stack_trace { 
};



extern void save_stack_trace(struct stack_trace *trace);

extern void save_stack_trace_tsk(struct task_struct *tsk,

				struct stack_trace *trace);



extern void print_stack_trace(struct stack_trace *trace, int spaces);

#else

# define save_stack_trace(trace)			do { } while (0)

# define save_stack_trace_tsk(tsk, trace)		do { } while (0)

# define print_stack_trace(trace, spaces)		do { } while (0)

#endif