diff mbox

[IDLESTAT,2/2] Add cpu topology info.

Message ID 1376038372-15666-1-git-send-email-shaojie.sun@linaro.com
State New
Headers show

Commit Message

sunshaojie Aug. 9, 2013, 8:52 a.m. UTC
When it can read cpu topology info, CPU idle state is shown ordered
by topology.
When it can't read cpu topology info, CPU idle state is shown in
old order.

Signed-off-by: Shaojie Sun <shaojie.sun@linaro.com>
---
 Makefile   |    2 +-
 idlestat.c |  237 ++++++++++++++++---------
 idlestat.h |   38 ++++
 list.h     |  563 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 topology.c |  485 +++++++++++++++++++++++++++++++++++++++++++++++++++
 topology.h |   51 ++++++
 utils.c    |   36 ++++
 utils.h    |    2 +
 8 files changed, 1331 insertions(+), 83 deletions(-)
 create mode 100644 idlestat.h
 create mode 100644 list.h
 create mode 100644 topology.c
 create mode 100644 topology.h

Comments

sunshaojie Aug. 9, 2013, 9:04 a.m. UTC | #1
Hi daniel.
      I do some test. And the test resultes are same.

./idlestat -t 10 foo
./idlestat foo

 And I create a mirror of idlesat tool in here.
https://git.linaro.org/gitweb?p=people/shaojie.sun/public_git/idlestat.git;a=summary
Daniel Lezcano Sept. 2, 2013, 2:22 p.m. UTC | #2
On 08/09/2013 11:04 AM, Shaojie Sun wrote:
> Hi daniel.
>       I do some test. And the test resultes are same.
> 
> ./idlestat -t 10 foo
> ./idlestat foo
> 
>  And I create a mirror of idlesat tool in here.
> https://git.linaro.org/gitweb?p=people/shaojie.sun/public_git/idlestat.git;a=summary

Hi Shaojie,

could you send a patchset based on:

git://git.linaro.org/people/dlezcano/idlestat.git

I will do some review, testing and commit the patches.

If Vincent or Viresh can also do some testing on it, that would be nice.

At this point, you will take the maintainership of the tool. I will
update JIRA with a set of tasks for you to improve the tool.

Thanks
  -- Daniel
diff mbox

Patch

diff --git a/Makefile b/Makefile
index 05c3f4f..7f2ff07 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@ 
 CFLAGS?=-g -Wall
 CC?=gcc
 
-OBJS = idlestat.o trace.o utils.o
+OBJS = idlestat.o topology.o trace.o utils.o
 
 default: idlestat
 
diff --git a/idlestat.c b/idlestat.c
index 069a1f3..e3794a8 100644
--- a/idlestat.c
+++ b/idlestat.c
@@ -12,43 +12,14 @@ 
 #include <sys/signal.h>
 #include <sys/resource.h>
 
+#include "list.h"
+#include "idlestat.h"
 #include "utils.h"
 #include "trace.h"
-
-#define BUFSIZE 256
-#define MAXCSTATE 8
-#define MAX(A,B) (A > B ? A : B)
-#define MIN(A,B) (A < B ? A : B)
-#define AVG(A,B,I) ((A) + ((B - A) / (I)))
+#include "topology.h"
 
 static char buffer[BUFSIZE];
 
-struct cpuidle_data {
-	double begin;
-	double end;
-	double duration;
-};
-
-struct cpuidle_cstate {
-	struct cpuidle_data *data;
-	int nrdata;
-	double avg_time;
-	double max_time;
-	double min_time;
-	double duration;
-};
-
-struct cpuidle_cstates {
-	struct cpuidle_cstate cstate[MAXCSTATE];
-	int last_cstate;
-	int cstate_max;
-};
-
-struct cpuidle_datas {
-	struct cpuidle_cstates *cstates;
-	int nrcpus;
-};
-
 static inline int error(const char *str)
 {
 	perror(str);
@@ -61,65 +32,70 @@  static inline void *ptrerror(const char *str)
 	return NULL;
 }
 
-static int dump_data(struct cpuidle_datas *datas, int state, int count)
+static int dump_cstates(struct cpuidle_cstates *cstates, int state,
+			int count, char *str)
 {
-	int i = 0, j, k, nrcpus = datas->nrcpus;
-	struct cpuidle_cstates *cstates;
+	int j, k;
 	struct cpuidle_cstate *cstate;
 
-	do {
-		cstates = &datas->cstates[i];
+	for (j = 0; j < cstates->cstate_max + 1; j++) {
 
-		for (j = 0; j < cstates->cstate_max + 1; j++) {
+		if (state != -1 && state != j)
+			continue;
 
-			if (state != -1 && state != j)
-				continue;
+		cstate = &cstates->cstate[j];
 
-			cstate = &cstates->cstate[j];
+		for (k = 0; k < MIN(count, cstate->nrdata); k++) {
+			printf("%lf %d\n", cstate->data[k].begin, j);
+			printf("%lf 0\n", cstate->data[k].end);
+		}
 
-			for (k = 0; k < MIN(count, cstate->nrdata); k++) {
-				printf("%lf %d\n", cstate->data[k].begin, j);
-				printf("%lf 0\n", cstate->data[k].end);
-			}
+		/* add a break */
+		printf("\n");
+	}
 
-			/* add a break */
-			printf("\n");
-		}
+	return 0;
+}
 
-		i++;
+static int display_cstates(struct cpuidle_cstates *cstates, int state,
+			int count, char *str)
+{
+	int j;
+	struct cpuidle_cstate *cstate;
 
-	} while (i < nrcpus && nrcpus != -1);
+	for (j = 0; j < cstates->cstate_max + 1; j++) {
+
+		if (state != -1 && state != j)
+			continue;
+
+		cstate = &cstates->cstate[j];
+
+		printf("%s", str);
+		printf("/state%d, %d hits, total %.2lfus," \
+		       "avg %.2lfus, min %.2lfus, max %.2lfus\n",
+		       j, cstate->nrdata, cstate->duration,
+		       cstate->avg_time, cstate->min_time,
+		       cstate->max_time);
+	}
 
 	return 0;
 }
 
-static int display_data(struct cpuidle_datas *datas, int state)
+int dump_all_data(struct cpuidle_datas *datas, int state, int count,
+		int (*dump)(struct cpuidle_cstates *, int,  int, char *))
 {
-	int i = 0, j, nrcpus = datas->nrcpus;
+	int i = 0, nrcpus = datas->nrcpus;
 	struct cpuidle_cstates *cstates;
-	struct cpuidle_cstate *cstate;
 
 	do {
 		cstates = &datas->cstates[i];
 
-		for (j = 0; j < cstates->cstate_max + 1; j++) {
-
-			if (state != -1 && state != j)
-				continue;
-
-			cstate = &cstates->cstate[j];
+		if (nrcpus == -1)
+			sprintf(buffer, "cluster");
+		else
+			sprintf(buffer, "cpu%d", i);
 
-			if (nrcpus == -1)
-				printf("cluster");
-			else
-				printf("cpu%d", i);
-
-			printf("/state%d, %d hits, total %.2lfus, "\
-			       "avg %.2lfus, min %.2lfus, max %.2lfus\n",
-			       j, cstate->nrdata, cstate->duration,
-			       cstate->avg_time, cstate->min_time,
-			       cstate->max_time);
-		}
+		dump(cstates, state, count, buffer);
 
 		i++;
 
@@ -311,7 +287,8 @@  static struct cpuidle_datas *idlestat_load(const char *path)
 
 	datas->nrcpus = nrcpus;
 
-	/* TODO: read topology information */
+	/* read topology information */
+	read_cpu_topo_info(f);
 
 	for (start = 1; fgets(buffer, BUFSIZE, f); count++) {
 
@@ -376,6 +353,75 @@  struct cpuidle_datas *cluster_data(struct cpuidle_datas *datas)
 	return result;
 }
 
+
+struct cpuidle_cstates *core_cluster_data(struct cpu_core *s_core)
+{
+	struct cpuidle_cstate *c1, *cstates;
+	struct cpuidle_cstates *result;
+	struct cpu_cpu      *s_cpu;
+	int i;
+	int cstate_max = -1;
+
+	if (!s_core->is_ht)
+		list_for_each_entry(s_cpu, &s_core->cpu_head, list_cpu)
+			return s_cpu->cstates;
+
+	result = calloc(sizeof(*result), 1);
+	if (!result)
+		return NULL;
+
+	/* hack but negligeable overhead */
+	list_for_each_entry(s_cpu, &s_core->cpu_head, list_cpu)
+		cstate_max = MAX(cstate_max, s_cpu->cstates->cstate_max);
+	result->cstate_max = cstate_max;
+
+	for (i = 0; i < cstate_max + 1; i++) {
+		list_for_each_entry(s_cpu, &s_core->cpu_head, list_cpu) {
+			c1 = &s_cpu->cstates->cstate[i];
+
+			cstates = inter(cstates, c1);
+			if (!cstates)
+				continue;
+		}
+
+		result->cstate[i] = *cstates;
+	}
+
+	return result;
+}
+
+struct cpuidle_cstates *physical_cluster_data(struct cpu_physical *s_phy)
+{
+	struct cpuidle_cstate *c1, *cstates;
+	struct cpuidle_cstates *result;
+	struct cpu_core      *s_core;
+	int i;
+	int cstate_max = -1;
+
+	result = calloc(sizeof(*result), 1);
+	if (!result)
+		return NULL;
+
+	/* hack but negligeable overhead */
+	list_for_each_entry(s_core, &s_phy->core_head, list_core)
+		cstate_max = MAX(cstate_max, s_core->cstates->cstate_max);
+	result->cstate_max = cstate_max;
+
+	for (i = 0; i < cstate_max + 1; i++) {
+		list_for_each_entry(s_core, &s_phy->core_head, list_core) {
+			c1 = &s_core->cstates->cstate[i];
+
+			cstates = inter(cstates, c1);
+			if (!cstates)
+				continue;
+		}
+
+		result->cstate[i] = *cstates;
+	}
+
+	return result;
+}
+
 static int help(const char *cmd)
 {
 	fprintf(stderr, "%s [-d/--dump] [-c/--cstate=x] <file>\n", cmd);
@@ -506,7 +552,8 @@  static int idlestat_store(const char *path)
 	fprintf(f, "version = 1\n");
 	fprintf(f, "cpus=%d\n", ret);
 
-	/* TODO: add topology information here */
+	/* output topology information */
+	output_cpu_topo_info(f);
 
 	ret = idlestat_file_for_each_line(TRACE_FILE, f, store_line);
 
@@ -549,6 +596,7 @@  int main(int argc, char *argv[])
 	struct cpuidle_datas *cluster;
 	struct idledebug_options options;
 	struct rusage rusage;
+	int    ret;
 
 	/* We have to manipulate some files only accessible to root */
 	if (getuid()) {
@@ -559,9 +607,15 @@  int main(int argc, char *argv[])
 	if (getoptions(argc, argv, &options))
 		return 1;
 
+	/* init cpu topoinfo */
+	init_cpu_topo_info();
+
 	/* Acquisition time specified means we will get the traces */
 	if (options.duration) {
 
+		/* Read cpu topology info from sysfs */
+		read_sysfs_cpu_topo();
+
 		/* Stop tracing (just in case) */
 		if (idlestat_trace_enable(false))
 			return -1;
@@ -610,18 +664,34 @@  int main(int argc, char *argv[])
 
 	/* Compute cluster idle intersection between cpus belonging to
 	 * the same cluster
-	 * TODO: add topology information
 	 */
-	cluster = cluster_data(datas);
-	if (!cluster)
-		return 1;
-
-	if (options.dump > 0) {
-		dump_data(datas, options.cstate, options.iterations);
-		dump_data(cluster, options.cstate, options.iterations);
+	ret = establish_idledata_to_topo(datas);
+	if (!ret) {
+		if (options.dump > 0)
+			dump_cpu_topo_info(options.cstate, options.iterations,
+						dump_cstates);
+		else
+			dump_cpu_topo_info(options.cstate, options.iterations,
+						display_cstates);
 	} else {
-		display_data(datas, options.cstate);
-		display_data(cluster, options.cstate);
+		cluster = cluster_data(datas);
+		if (!cluster)
+			return 1;
+
+		if (options.dump > 0) {
+			dump_all_data(datas, options.cstate,
+					options.iterations, dump_cstates);
+			dump_all_data(cluster, options.cstate,
+					options.iterations, dump_cstates);
+		} else {
+			dump_all_data(datas, options.cstate,
+					options.iterations, display_cstates);
+			dump_all_data(cluster, options.cstate,
+					options.iterations, display_cstates);
+		}
+
+		free(cluster->cstates);
+		free(cluster);
 	}
 
 	/* Computation could be heavy, let's give some information
@@ -631,5 +701,8 @@  int main(int argc, char *argv[])
 		printf("max rss : %ld kB\n", rusage.ru_maxrss);
 	}
 
+	release_cpu_topo_cstates();
+	release_cpu_topo_info();
+
 	return 0;
 }
diff --git a/idlestat.h b/idlestat.h
new file mode 100644
index 0000000..de74ead
--- /dev/null
+++ b/idlestat.h
@@ -0,0 +1,38 @@ 
+
+#ifndef __IDLESTAT_H
+#define __IDLESTAT_H
+
+#define BUFSIZE 256
+#define MAXCSTATE 8
+#define MAX(A, B) (A > B ? A : B)
+#define MIN(A, B) (A < B ? A : B)
+#define AVG(A, B, I) ((A) + ((B - A) / (I)))
+
+struct cpuidle_data {
+	double begin;
+	double end;
+	double duration;
+};
+
+struct cpuidle_cstate {
+	struct cpuidle_data *data;
+	int nrdata;
+	double avg_time;
+	double max_time;
+	double min_time;
+	double duration;
+};
+
+struct cpuidle_cstates {
+	struct cpuidle_cstate cstate[MAXCSTATE];
+	int last_cstate;
+	int cstate_max;
+};
+
+struct cpuidle_datas {
+	struct cpuidle_cstates *cstates;
+	int nrcpus;
+};
+
+#endif
+
diff --git a/list.h b/list.h
new file mode 100644
index 0000000..6db4c62
--- /dev/null
+++ b/list.h
@@ -0,0 +1,563 @@ 
+#ifndef _LINUX_LIST_H
+#define _LINUX_LIST_H
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+#define LIST_POISON1 ((void *)0x00100100)
+#define LIST_POISON2 ((void *)0x00200200)
+
+struct list_head {
+	struct list_head *next, *prev;
+};
+
+/*
+ * Simple doubly linked list implementation.
+ *
+ * Some of the internal functions ("__xxx") are useful when
+ * manipulating whole lists rather than single entries, as
+ * sometimes we already know the next/prev entries and we can
+ * generate better code by using them directly rather than
+ * using the generic single-entry routines.
+ */
+
+#define LIST_HEAD_INIT(name) { &(name), &(name) }
+
+#define LIST_HEAD(name) \
+	struct list_head name = LIST_HEAD_INIT(name)
+
+static inline void INIT_LIST_HEAD(struct list_head *list)
+{
+	list->next = list;
+	list->prev = list;
+}
+
+/*
+ * Insert a new entry between two known consecutive entries.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ */
+static inline void __list_add(struct list_head *new,
+			      struct list_head *prev,
+			      struct list_head *next)
+{
+	next->prev = new;
+	new->next = next;
+	new->prev = prev;
+	prev->next = new;
+}
+
+/**
+ * list_add - add a new entry
+ * @new: new entry to be added
+ * @head: list head to add it after
+ *
+ * Insert a new entry after the specified head.
+ * This is good for implementing stacks.
+ */
+static inline void list_add(struct list_head *new, struct list_head *head)
+{
+	__list_add(new, head, head->next);
+}
+
+
+/**
+ * list_add_tail - add a new entry
+ * @new: new entry to be added
+ * @head: list head to add it before
+ *
+ * Insert a new entry before the specified head.
+ * This is useful for implementing queues.
+ */
+static inline void list_add_tail(struct list_head *new, struct list_head *head)
+{
+	__list_add(new, head->prev, head);
+}
+
+/*
+ * Delete a list entry by making the prev/next entries
+ * point to each other.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ */
+static inline void __list_del(struct list_head *prev, struct list_head *next)
+{
+	next->prev = prev;
+	prev->next = next;
+}
+
+/**
+ * list_del - deletes entry from list.
+ * @entry: the element to delete from the list.
+ * Note: list_empty() on entry does not return true after this, the entry is
+ * in an undefined state.
+ */
+static inline void __list_del_entry(struct list_head *entry)
+{
+	__list_del(entry->prev, entry->next);
+}
+
+static inline void list_del(struct list_head *entry)
+{
+	__list_del(entry->prev, entry->next);
+	entry->next = LIST_POISON1;
+	entry->prev = LIST_POISON2;
+}
+
+/**
+ * list_replace - replace old entry by new one
+ * @old : the element to be replaced
+ * @new : the new element to insert
+ *
+ * If @old was empty, it will be overwritten.
+ */
+static inline void list_replace(struct list_head *old,
+				struct list_head *new)
+{
+	new->next = old->next;
+	new->next->prev = new;
+	new->prev = old->prev;
+	new->prev->next = new;
+}
+
+static inline void list_replace_init(struct list_head *old,
+					struct list_head *new)
+{
+	list_replace(old, new);
+	INIT_LIST_HEAD(old);
+}
+
+/**
+ * list_del_init - deletes entry from list and reinitialize it.
+ * @entry: the element to delete from the list.
+ */
+static inline void list_del_init(struct list_head *entry)
+{
+	__list_del_entry(entry);
+	INIT_LIST_HEAD(entry);
+}
+
+/**
+ * list_move - delete from one list and add as another's head
+ * @list: the entry to move
+ * @head: the head that will precede our entry
+ */
+static inline void list_move(struct list_head *list, struct list_head *head)
+{
+	__list_del_entry(list);
+	list_add(list, head);
+}
+
+/**
+ * list_move_tail - delete from one list and add as another's tail
+ * @list: the entry to move
+ * @head: the head that will follow our entry
+ */
+static inline void list_move_tail(struct list_head *list,
+				  struct list_head *head)
+{
+	__list_del_entry(list);
+	list_add_tail(list, head);
+}
+
+/**
+ * list_is_last - tests whether @list is the last entry in list @head
+ * @list: the entry to test
+ * @head: the head of the list
+ */
+static inline int list_is_last(const struct list_head *list,
+				const struct list_head *head)
+{
+	return list->next == head;
+}
+
+/**
+ * list_empty - tests whether a list is empty
+ * @head: the list to test.
+ */
+static inline int list_empty(const struct list_head *head)
+{
+	return head->next == head;
+}
+
+/**
+ * list_empty_careful - tests whether a list is empty and not being modified
+ * @head: the list to test
+ *
+ * Description:
+ * tests whether a list is empty _and_ checks that no other CPU might be
+ * in the process of modifying either member (next or prev)
+ *
+ * NOTE: using list_empty_careful() without synchronization
+ * can only be safe if the only activity that can happen
+ * to the list entry is list_del_init(). Eg. it cannot be used
+ * if another CPU could re-list_add() it.
+ */
+static inline int list_empty_careful(const struct list_head *head)
+{
+	struct list_head *next = head->next;
+	return (next == head) && (next == head->prev);
+}
+
+/**
+ * list_rotate_left - rotate the list to the left
+ * @head: the head of the list
+ */
+static inline void list_rotate_left(struct list_head *head)
+{
+	struct list_head *first;
+
+	if (!list_empty(head)) {
+		first = head->next;
+		list_move_tail(first, head);
+	}
+}
+
+/**
+ * list_is_singular - tests whether a list has just one entry.
+ * @head: the list to test.
+ */
+static inline int list_is_singular(const struct list_head *head)
+{
+	return !list_empty(head) && (head->next == head->prev);
+}
+
+static inline void __list_cut_position(struct list_head *list,
+		struct list_head *head, struct list_head *entry)
+{
+	struct list_head *new_first = entry->next;
+	list->next = head->next;
+	list->next->prev = list;
+	list->prev = entry;
+	entry->next = list;
+	head->next = new_first;
+	new_first->prev = head;
+}
+
+/**
+ * list_cut_position - cut a list into two
+ * @list: a new list to add all removed entries
+ * @head: a list with entries
+ * @entry: an entry within head, could be the head itself
+ *	and if so we won't cut the list
+ *
+ * This helper moves the initial part of @head, up to and
+ * including @entry, from @head to @list. You should
+ * pass on @entry an element you know is on @head. @list
+ * should be an empty list or a list you do not care about
+ * losing its data.
+ *
+ */
+static inline void list_cut_position(struct list_head *list,
+		struct list_head *head, struct list_head *entry)
+{
+	if (list_empty(head))
+		return;
+	if (list_is_singular(head) &&
+		(head->next != entry && head != entry))
+		return;
+	if (entry == head)
+		INIT_LIST_HEAD(list);
+	else
+		__list_cut_position(list, head, entry);
+}
+
+static inline void __list_splice(const struct list_head *list,
+				 struct list_head *prev,
+				 struct list_head *next)
+{
+	struct list_head *first = list->next;
+	struct list_head *last = list->prev;
+
+	first->prev = prev;
+	prev->next = first;
+
+	last->next = next;
+	next->prev = last;
+}
+
+/**
+ * list_splice - join two lists, this is designed for stacks
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ */
+static inline void list_splice(const struct list_head *list,
+				struct list_head *head)
+{
+	if (!list_empty(list))
+		__list_splice(list, head, head->next);
+}
+
+/**
+ * list_splice_tail - join two lists, each list being a queue
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ */
+static inline void list_splice_tail(struct list_head *list,
+				struct list_head *head)
+{
+	if (!list_empty(list))
+		__list_splice(list, head->prev, head);
+}
+
+/**
+ * list_splice_init - join two lists and reinitialise the emptied list.
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ *
+ * The list at @list is reinitialised
+ */
+static inline void list_splice_init(struct list_head *list,
+				    struct list_head *head)
+{
+	if (!list_empty(list)) {
+		__list_splice(list, head, head->next);
+		INIT_LIST_HEAD(list);
+	}
+}
+
+/**
+ * list_splice_tail_init - join two lists and reinitialise the emptied list
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ *
+ * Each of the lists is a queue.
+ * The list at @list is reinitialised
+ */
+static inline void list_splice_tail_init(struct list_head *list,
+					 struct list_head *head)
+{
+	if (!list_empty(list)) {
+		__list_splice(list, head->prev, head);
+		INIT_LIST_HEAD(list);
+	}
+}
+
+#undef offsetof
+#define offsetof(s, m)      ((size_t)&(((s *)0)->m))
+
+#undef container_of
+#define container_of(ptr, type, member) ({			\
+	const typeof(((type *)0)->member) * __mptr = (ptr);	\
+	(type *)((char *)__mptr - offsetof(type, member)); })
+
+/**
+ * list_entry - get the struct for this entry
+ * @ptr:	the &struct list_head pointer.
+ * @type:	the type of the struct this is embedded in.
+ * @member:	the name of the list_struct within the struct.
+ */
+#define list_entry(ptr, type, member) \
+	container_of(ptr, type, member)
+
+/**
+ * list_first_entry - get the first element from a list
+ * @ptr:	the list head to take the element from.
+ * @type:	the type of the struct this is embedded in.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Note, that list is expected to be not empty.
+ */
+#define list_first_entry(ptr, type, member) \
+	list_entry((ptr)->next, type, member)
+
+/**
+ * list_for_each	-	iterate over a list
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @head:	the head for your list.
+ */
+#define list_for_each(pos, head) \
+	for (pos = (head)->next; pos != (head); pos = pos->next)
+
+/**
+ * __list_for_each	-	iterate over a list
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @head:	the head for your list.
+ *
+ * This variant doesn't differ from list_for_each() any more.
+ * We don't do prefetching in either case.
+ */
+#define __list_for_each(pos, head) \
+	for (pos = (head)->next; pos != (head); pos = pos->next)
+
+/**
+ * list_for_each_prev	-	iterate over a list backwards
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @head:	the head for your list.
+ */
+#define list_for_each_prev(pos, head) \
+	for (pos = (head)->prev; pos != (head); pos = pos->prev)
+
+/**
+ * list_for_each_safe - iterate over a list safe against removal of list entry
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @n:		another &struct list_head to use as temporary storage
+ * @head:	the head for your list.
+ */
+#define list_for_each_safe(pos, n, head) \
+	for (pos = (head)->next, n = pos->next; pos != (head); \
+		pos = n, n = pos->next)
+
+/**
+ * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @n:		another &struct list_head to use as temporary storage
+ * @head:	the head for your list.
+ */
+#define list_for_each_prev_safe(pos, n, head) \
+	for (pos = (head)->prev, n = pos->prev; \
+	     pos != (head); \
+	     pos = n, n = pos->prev)
+
+/**
+ * list_for_each_entry	-	iterate over list of given type
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ */
+#define list_for_each_entry(pos, head, member)				\
+	for (pos = list_entry((head)->next, typeof(*pos), member);	\
+	     &pos->member != (head);	\
+	     pos = list_entry(pos->member.next, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_reverse - iterate backwards over list of given type.
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ */
+#define list_for_each_entry_reverse(pos, head, member)			\
+	for (pos = list_entry((head)->prev, typeof(*pos), member);	\
+	     &pos->member != (head);	\
+	     pos = list_entry(pos->member.prev, typeof(*pos), member))
+
+/**
+ * list_prepare_entry - prepare a entry for use in list_for_each_entry_continue()
+ * @pos:	the type * to use as a start point
+ * @head:	the head of the list
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Prepares a entry for use as a start point in list_for_each_entry_continue().
+ */
+#define list_prepare_entry(pos, head, member) \
+	((pos) ? : list_entry(head, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_continue - continue iteration over list of given type
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Continue to iterate over list of given type, continuing after
+ * the current position.
+ */
+#define list_for_each_entry_continue(pos, head, member)		\
+	for (pos = list_entry(pos->member.next, typeof(*pos), member);	\
+	     &pos->member != (head);	\
+	     pos = list_entry(pos->member.next, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_continue_reverse - iterate backwards from the given point
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Start to iterate over list of given type backwards, continuing after
+ * the current position.
+ */
+#define list_for_each_entry_continue_reverse(pos, head, member)		\
+	for (pos = list_entry(pos->member.prev, typeof(*pos), member);	\
+	     &pos->member != (head);	\
+	     pos = list_entry(pos->member.prev, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_from - iterate over list of given type from the current point
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Iterate over list of given type, continuing from current position.
+ */
+#define list_for_each_entry_from(pos, head, member)			\
+	for (; &pos->member != (head);	\
+	     pos = list_entry(pos->member.next, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
+ * @pos:	the type * to use as a loop cursor.
+ * @n:		another type * to use as temporary storage
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ */
+#define list_for_each_entry_safe(pos, n, head, member)			\
+	for (pos = list_entry((head)->next, typeof(*pos), member),	\
+		n = list_entry(pos->member.next, typeof(*pos), member);	\
+	     &pos->member != (head);					\
+	     pos = n, n = list_entry(n->member.next, typeof(*n), member))
+
+/**
+ * list_for_each_entry_safe_continue - continue list iteration safe against removal
+ * @pos:	the type * to use as a loop cursor.
+ * @n:		another type * to use as temporary storage
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Iterate over list of given type, continuing after current point,
+ * safe against removal of list entry.
+ */
+#define list_for_each_entry_safe_continue(pos, n, head, member)		\
+	for (pos = list_entry(pos->member.next, typeof(*pos), member),	\
+		n = list_entry(pos->member.next, typeof(*pos), member);	\
+	     &pos->member != (head);					\
+	     pos = n, n = list_entry(n->member.next, typeof(*n), member))
+
+/**
+ * list_for_each_entry_safe_from - iterate over list from current point safe against removal
+ * @pos:	the type * to use as a loop cursor.
+ * @n:		another type * to use as temporary storage
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Iterate over list of given type from current point, safe against
+ * removal of list entry.
+ */
+#define list_for_each_entry_safe_from(pos, n, head, member)		\
+	for (n = list_entry(pos->member.next, typeof(*pos), member);	\
+	     &pos->member != (head);					\
+	     pos = n, n = list_entry(n->member.next, typeof(*n), member))
+
+/**
+ * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
+ * @pos:	the type * to use as a loop cursor.
+ * @n:		another type * to use as temporary storage
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Iterate backwards over list of given type, safe against removal
+ * of list entry.
+ */
+#define list_for_each_entry_safe_reverse(pos, n, head, member)		\
+	for (pos = list_entry((head)->prev, typeof(*pos), member),	\
+		n = list_entry(pos->member.prev, typeof(*pos), member);	\
+	     &pos->member != (head);					\
+	     pos = n, n = list_entry(n->member.prev, typeof(*n), member))
+
+/**
+ * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
+ * @pos:	the loop cursor used in the list_for_each_entry_safe loop
+ * @n:		temporary storage used in list_for_each_entry_safe
+ * @member:	the name of the list_struct within the struct.
+ *
+ * list_safe_reset_next is not safe to use in general if the list may be
+ * modified concurrently (eg. the lock is dropped in the loop body). An
+ * exception to this is if the cursor element (pos) is pinned in the list,
+ * and list_safe_reset_next is called after re-taking the lock and before
+ * completing the current iteration of the loop body.
+ */
+#define list_safe_reset_next(pos, n, member)				\
+	(n = list_entry(pos->member.next, typeof(*pos), member))
+
+#endif
diff --git a/topology.c b/topology.c
new file mode 100644
index 0000000..e93381c
--- /dev/null
+++ b/topology.c
@@ -0,0 +1,485 @@ 
+/*****************************************************************************
+ * Copyright (C) 2013, Linaro Limited.
+ *
+ * This file is part of cpu_topology.
+ *
+ * All rights reserved.
+ *
+ * Contributors:
+ *     Shaojie Sun <shaojie.sun@linaro.org> (Hislicon technologies)
+ *       - initial API and implementation
+ *
+ *****************************************************************************/
+
+#define  _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include <string.h>
+#include <dirent.h>
+#include <ctype.h>
+#include <sys/stat.h>
+
+#include "list.h"
+#include "utils.h"
+#include "topology.h"
+#include "idlestat.h"
+
+struct cpu_topology g_cpu_topo_list;
+
+struct topology_info {
+	int physical_id;
+	int core_id;
+	int cpu_id;
+};
+
+struct list_info {
+	struct list_head hlist;
+	int id;
+};
+
+struct list_head *check_exist_from_head(struct list_head *head, int id)
+{
+	struct list_head *tmp;
+
+	list_for_each(tmp, head) {
+		if (id == ((struct list_info *)tmp)->id)
+			return tmp;
+	}
+
+	return NULL;
+}
+
+struct list_head *check_pos_from_head(struct list_head *head, int id)
+{
+	struct list_head *tmp;
+
+	list_for_each(tmp, head) {
+		if (id < ((struct list_info *)tmp)->id)
+			break;
+	}
+
+	return tmp->prev;
+}
+
+int add_topo_info(struct cpu_topology *topo_list, struct topology_info *info)
+{
+	struct cpu_physical *s_phy;
+	struct cpu_core     *s_core;
+	struct cpu_cpu      *s_cpu = NULL;
+	struct list_head    *ptr;
+
+	/* add cpu physical info */
+	ptr = check_exist_from_head(&topo_list->physical_head,
+					info->physical_id);
+	if (!ptr) {
+		s_phy = calloc(sizeof(struct cpu_physical), 1);
+		if (!s_phy)
+			return -1;
+
+		s_phy->core_num = 0;
+		s_phy->physical_id = info->physical_id;
+		INIT_LIST_HEAD(&s_phy->core_head);
+
+		ptr = check_pos_from_head(&topo_list->physical_head,
+						s_phy->physical_id);
+		list_add(&s_phy->list_physical, ptr);
+		topo_list->physical_num++;
+	} else {
+		s_phy = list_entry(ptr, struct cpu_physical,
+						list_physical);
+	}
+
+	/* add cpu core info */
+	ptr = check_exist_from_head(&s_phy->core_head, info->core_id);
+	if (!ptr) {
+		s_core = calloc(sizeof(struct cpu_core), 1);
+		if (!s_core)
+			return -1;
+
+		s_core->cpu_num = 0;
+		s_core->is_ht = false;
+		s_core->core_id = info->core_id;
+		INIT_LIST_HEAD(&s_core->cpu_head);
+
+		ptr = check_pos_from_head(&s_phy->core_head,
+						s_core->core_id);
+		list_add(&s_core->list_core, ptr);
+		s_phy->core_num++;
+
+	} else {
+		s_core = list_entry(ptr, struct cpu_core, list_core);
+	}
+
+	/* add cpu info */
+	ptr = check_exist_from_head(&s_core->cpu_head, info->cpu_id);
+	if (!ptr) {
+		s_cpu = calloc(sizeof(struct cpu_cpu), 1);
+		if (!s_core)
+			return -1;
+
+		s_cpu->cpu_id = info->cpu_id;
+
+		ptr = check_pos_from_head(&s_core->cpu_head, s_cpu->cpu_id);
+		list_add(&s_cpu->list_cpu, ptr);
+		s_core->cpu_num++;
+		if (s_core->cpu_num > 1)
+			s_core->is_ht = true;
+	}
+
+	return 0;
+}
+
+void free_cpu_cpu_list(struct list_head *head)
+{
+	struct cpu_cpu *lcpu, *n;
+
+	list_for_each_entry_safe(lcpu, n, head, list_cpu) {
+		list_del(&lcpu->list_cpu);
+		free(lcpu);
+	}
+}
+
+void free_cpu_core_list(struct list_head *head)
+{
+	struct cpu_core *lcore, *n;
+
+	list_for_each_entry_safe(lcore, n, head, list_core) {
+		free_cpu_cpu_list(&lcore->cpu_head);
+		list_del(&lcore->list_core);
+		free(lcore);
+	}
+}
+
+void free_cpu_topology(struct list_head *head)
+{
+	struct cpu_physical *lphysical, *n;
+
+	list_for_each_entry_safe(lphysical, n, head, list_physical) {
+		free_cpu_core_list(&lphysical->core_head);
+		list_del(&lphysical->list_physical);
+		free(lphysical);
+	}
+}
+
+int output_topo_info(struct cpu_topology *topo_list)
+{
+	struct cpu_physical *s_phy;
+	struct cpu_core     *s_core;
+	struct cpu_cpu      *s_cpu;
+
+	list_for_each_entry(s_phy, &topo_list->physical_head, list_physical) {
+		printf("cluster%c:\n", s_phy->physical_id + 'A');
+		list_for_each_entry(s_core, &s_phy->core_head, list_core) {
+			if (s_core->is_ht) {
+				printf("\tcore%d\n", s_core->core_id);
+				list_for_each_entry(s_cpu, &s_core->cpu_head, list_cpu)
+					printf("\t\tcpu%d\n", s_cpu->cpu_id);
+			} else {
+				list_for_each_entry(s_cpu, &s_core->cpu_head, list_cpu)
+					printf("\tcpu%d\n", s_cpu->cpu_id);
+			}
+		}
+	}
+
+	return 0;
+}
+
+int outfile_topo_info(FILE *f, struct cpu_topology *topo_list)
+{
+	struct cpu_physical *s_phy;
+	struct cpu_core     *s_core;
+	struct cpu_cpu      *s_cpu;
+
+	list_for_each_entry(s_phy, &topo_list->physical_head, list_physical) {
+		fprintf(f, "cluster%c:\n", s_phy->physical_id + 'A');
+		list_for_each_entry(s_core, &s_phy->core_head, list_core) {
+			if (s_core->is_ht) {
+				fprintf(f, "\tcore%d\n", s_core->core_id);
+				list_for_each_entry(s_cpu, &s_core->cpu_head, list_cpu)
+					fprintf(f, "\t\tcpu%d\n", s_cpu->cpu_id);
+			} else {
+				list_for_each_entry(s_cpu, &s_core->cpu_head, list_cpu)
+					fprintf(f, "\tcpu%d\n", s_cpu->cpu_id);
+			}
+		}
+	}
+
+	return 0;
+}
+
+struct cpu_cpu *find_cpu_point(struct cpu_topology *topo_list, int cpuid)
+{
+	struct cpu_physical *s_phy;
+	struct cpu_core     *s_core;
+	struct cpu_cpu      *s_cpu;
+
+	list_for_each_entry(s_phy, &topo_list->physical_head, list_physical)
+		list_for_each_entry(s_core, &s_phy->core_head, list_core)
+			list_for_each_entry(s_cpu, &s_core->cpu_head, list_cpu)
+				if (s_cpu->cpu_id == cpuid)
+					return s_cpu;
+
+	return NULL;
+}
+
+static inline int read_topology_cb(char *path, struct topology_info *info)
+{
+	file_read_value(path, "core_id", "%d", &info->core_id);
+	file_read_value(path, "physical_package_id", "%d", &info->physical_id);
+
+	return 0;
+}
+
+typedef int (*folder_filter_t)(const char *name);
+
+static int cpu_filter_cb(const char *name)
+{
+	/* let's ignore some directories in order to avoid to be
+	 * pulled inside the sysfs circular symlinks mess/hell
+	 * (choose the word which fit better)*/
+	if (!strcmp(name, "cpuidle"))
+		return 1;
+
+	if (!strcmp(name, "cpufreq"))
+		return 1;
+
+	return 0;
+}
+
+/*
+ * This function will browse the directory structure and build a
+ * reflecting the content of the directory tree.
+ *
+ * @path   : the root node of the folder
+ * @filter : a callback to filter out the directories
+ * Returns 0 on success, -1 otherwise
+ */
+static int topo_folder_scan(char *path, folder_filter_t filter)
+{
+	DIR *dir, *dir_topology;
+	char *basedir, *newpath;
+	struct dirent dirent, *direntp;
+	struct stat s;
+	int ret = 0;
+
+	dir = opendir(path);
+	if (!dir) {
+		printf("error: unable to open directory %s\n", path);
+		return -1;
+	}
+
+	ret = asprintf(&basedir, "%s", path);
+	if (ret < 0)
+		return -1;
+
+	while (!readdir_r(dir, &dirent, &direntp)) {
+
+		if (!direntp)
+			break;
+
+		if (direntp->d_name[0] == '.')
+			continue;
+
+		if (filter && filter(direntp->d_name))
+			continue;
+
+		if (!strstr(direntp->d_name, "cpu"))
+			continue;
+
+		ret = asprintf(&newpath, "%s/%s/%s", basedir,
+				direntp->d_name, "topology");
+		if (ret < 0)
+			goto out_free_basedir;
+
+		ret = stat(newpath, &s);
+		if (ret)
+			goto out_free_newpath;
+
+		if (S_ISDIR(s.st_mode) || (S_ISLNK(s.st_mode))) {
+			struct topology_info cpu_info;
+
+			dir_topology = opendir(path);
+			if (!dir_topology)
+				continue;
+
+			read_topology_cb(newpath, &cpu_info);
+			sscanf(direntp->d_name, "cpu%d", &cpu_info.cpu_id);
+			add_topo_info(&g_cpu_topo_list, &cpu_info);
+		}
+
+	out_free_newpath:
+		free(newpath);
+
+		if (ret)
+			break;
+	}
+
+out_free_basedir:
+	free(basedir);
+
+	closedir(dir);
+
+	return ret;
+}
+
+
+int init_cpu_topo_info(void)
+{
+	INIT_LIST_HEAD(&g_cpu_topo_list.physical_head);
+	g_cpu_topo_list.physical_num = 0;
+
+	return 0;
+}
+
+int read_sysfs_cpu_topo(void)
+{
+	topo_folder_scan("/sys/devices/system/cpu", cpu_filter_cb);
+
+	return 0;
+}
+
+int read_cpu_topo_info(FILE *f)
+{
+	int ret = 0;
+	struct topology_info cpu_info;
+	bool is_ht = false;
+	char buffer[BUFSIZE];
+	char pid;
+
+	fgets(buffer, BUFSIZE, f);
+	do {
+		ret = sscanf(buffer, "cluster%c", &pid);
+		if (!ret)
+			break;
+
+		cpu_info.physical_id = pid - 'A';
+
+		fgets(buffer, BUFSIZE, f);
+		ret = sscanf(buffer, "\tcore%u", &cpu_info.core_id);
+		if (ret) {
+			is_ht = true;
+			fgets(buffer, BUFSIZE, f);
+		} else {
+			is_ht = false;
+		}
+
+		do {
+			if (!is_ht) {
+				ret = sscanf(buffer, "\tcpu%u", &cpu_info.cpu_id);
+				cpu_info.core_id = cpu_info.cpu_id;
+			} else {
+				ret = sscanf(buffer, "\t\tcpu%u", &cpu_info.cpu_id);
+			}
+
+			if (!ret)
+				break;
+
+			add_topo_info(&g_cpu_topo_list, &cpu_info);
+
+			fgets(buffer, BUFSIZE, f);
+		} while (1);
+
+	} while (1);
+
+	/* output_topo_info(&g_cpu_topo_list); */
+
+	return 0;
+}
+
+int release_cpu_topo_info(void)
+{
+	/* free alloced memory */
+	free_cpu_topology(&g_cpu_topo_list.physical_head);
+
+	return 0;
+}
+
+int output_cpu_topo_info(FILE *f)
+{
+	outfile_topo_info(f, &g_cpu_topo_list);
+
+	return 0;
+}
+
+int establish_idledata_to_topo(struct cpuidle_datas *datas)
+{
+	struct cpu_physical *s_phy;
+	struct cpu_core     *s_core;
+	struct cpu_cpu      *s_cpu;
+	int    i;
+	int    has_topo = 0;
+
+	for (i = 0; i < datas->nrcpus; i++) {
+		s_cpu = find_cpu_point(&g_cpu_topo_list, i);
+		if (s_cpu) {
+			s_cpu->cstates = &datas->cstates[i];
+			has_topo = 1;
+		}
+	}
+
+	if (!has_topo)
+		return -1;
+
+	list_for_each_entry(s_phy, &g_cpu_topo_list.physical_head, list_physical)
+		list_for_each_entry(s_core, &s_phy->core_head, list_core)
+			s_core->cstates = core_cluster_data(s_core);
+
+	list_for_each_entry(s_phy, &g_cpu_topo_list.physical_head, list_physical)
+		s_phy->cstates = physical_cluster_data(s_phy);
+
+	return 0;
+}
+
+int dump_cpu_topo_info(int state, int count,
+	int (*dump)(struct cpuidle_cstates *, int,  int, char *))
+{
+	struct cpu_physical *s_phy;
+	struct cpu_core     *s_core;
+	struct cpu_cpu      *s_cpu;
+	char   tmp[30];
+	int    tab = 0;
+
+	list_for_each_entry(s_phy, &g_cpu_topo_list.physical_head, list_physical) {
+		sprintf(tmp, "cluster%c", s_phy->physical_id + 'A');
+		dump(s_phy->cstates, state, count, tmp);
+
+		list_for_each_entry(s_core, &s_phy->core_head, list_core) {
+			if (s_core->is_ht) {
+				sprintf(tmp, "\tcore%d", s_core->core_id);
+				dump(s_core->cstates, state, count, tmp);
+
+				tab = 1;
+			} else {
+				tab = 0;
+			}
+
+			list_for_each_entry(s_cpu, &s_core->cpu_head, list_cpu) {
+				sprintf(tmp, "%scpu%d", tab ? "\t\t" : "\t", s_cpu->cpu_id);
+				dump(s_cpu->cstates, state, count, tmp);
+			}
+		}
+	}
+
+	return 0;
+}
+
+int release_cpu_topo_cstates(void)
+{
+	struct cpu_physical *s_phy;
+	struct cpu_core     *s_core;
+
+	list_for_each_entry(s_phy, &g_cpu_topo_list.physical_head, list_physical) {
+		free(s_phy->cstates);
+		s_phy->cstates = NULL;
+		list_for_each_entry(s_core, &s_phy->core_head, list_core)
+			if (s_core->is_ht) {
+				free(s_core->cstates);
+				s_core->cstates = NULL;
+			}
+	}
+
+	return 0;
+}
diff --git a/topology.h b/topology.h
new file mode 100644
index 0000000..b7d5a0e
--- /dev/null
+++ b/topology.h
@@ -0,0 +1,51 @@ 
+
+#ifndef __TOPOLOGY_H
+#define __TOPOLOGY_H
+
+#include "list.h"
+#include "idlestat.h"
+
+struct cpu_cpu {
+	struct list_head list_cpu;
+	int cpu_id;
+	struct cpuidle_cstates *cstates;
+};
+
+struct cpu_core {
+	struct list_head list_core;
+	int core_id;
+	struct list_head cpu_head;
+	int cpu_num;
+	bool is_ht;
+	struct cpuidle_cstates *cstates;
+};
+
+struct cpu_physical {
+	struct list_head list_physical;
+	int physical_id;
+	struct list_head core_head;
+	int core_num;
+	struct cpuidle_cstates *cstates;
+};
+
+struct cpu_topology {
+	struct list_head physical_head;
+	int physical_num;
+};
+
+extern int init_cpu_topo_info(void);
+extern int read_cpu_topo_info(FILE *f);
+extern int read_sysfs_cpu_topo(void);
+extern int release_cpu_topo_info(void);
+extern int output_cpu_topo_info(FILE *f);
+extern int establish_idledata_to_topo(struct cpuidle_datas *datas);
+extern int release_cpu_topo_cstates(void);
+extern int dump_cpu_topo_info(int state, int count,
+		int (*dump)(struct cpuidle_cstates *, int,  int, char *));
+
+
+extern struct cpuidle_cstates *core_cluster_data(struct cpu_core *s_core);
+extern struct cpuidle_cstates *physical_cluster_data(struct cpu_physical *s_phy);
+
+#endif
+
diff --git a/utils.c b/utils.c
index 2b2cac1..e391a6d 100644
--- a/utils.c
+++ b/utils.c
@@ -53,3 +53,39 @@  int store_line(const char *line, void *data)
 
 	return 0;
 }
+
+/*
+ * This functions is a helper to read a specific file content and store
+ * the content inside a variable pointer passed as parameter, the format
+ * parameter gives the variable type to be read from the file.
+ *
+ * @path : directory path containing the file
+ * @name : name of the file to be read
+ * @format : the format of the format
+ * @value : a pointer to a variable to store the content of the file
+ * Returns 0 on success, -1 otherwise
+ */
+int file_read_value(const char *path, const char *name,
+			const char *format, void *value)
+{
+	FILE *file;
+	char *rpath;
+	int ret;
+
+	ret = asprintf(&rpath, "%s/%s", path, name);
+	if (ret < 0)
+		return ret;
+
+	file = fopen(rpath, "r");
+	if (!file) {
+		ret = -1;
+		goto out_free;
+	}
+
+	ret = fscanf(file, format, value) == EOF ? -1 : 0;
+
+	fclose(file);
+out_free:
+	free(rpath);
+	return ret;
+}
diff --git a/utils.h b/utils.h
index 950cf26..acd226a 100644
--- a/utils.h
+++ b/utils.h
@@ -5,5 +5,7 @@ 
 extern int write_int(const char *path, int val);
 extern int read_int(const char *path, int *val);
 extern int store_line(const char *line, void *data);
+extern int file_read_value(const char *path, const char *name,
+				const char *format, void *value);
 
 #endif