cgroup.c revision ed81ee199ec8f3cdfcdc78ff067a0397c3b02f5f 
1/*
2 * Code related to setting up a blkio cgroup
3 */
4#include <stdio.h>
5#include <stdlib.h>
6#include "fio.h"
7#include "flist.h"
8#include "cgroup.h"
9#include "smalloc.h"
10
11static struct fio_mutex *lock;
12
13struct cgroup_member {
14	struct flist_head list;
15	char *root;
16};
17
18static void add_cgroup(const char *name, struct flist_head *clist)
19{
20	struct cgroup_member *cm;
21
22	cm = smalloc(sizeof(*cm));
23	INIT_FLIST_HEAD(&cm->list);
24	cm->root = smalloc_strdup(name);
25
26	fio_mutex_down(lock);
27	flist_add_tail(&cm->list, clist);
28	fio_mutex_up(lock);
29}
30
31void cgroup_kill(struct flist_head *clist)
32{
33	struct flist_head *n, *tmp;
34	struct cgroup_member *cm;
35
36	fio_mutex_down(lock);
37
38	flist_for_each_safe(n, tmp, clist) {
39		cm = flist_entry(n, struct cgroup_member, list);
40		rmdir(cm->root);
41		flist_del(&cm->list);
42		sfree(cm->root);
43		sfree(cm);
44	}
45
46	fio_mutex_up(lock);
47}
48
49/*
50 * Check if the given root appears valid
51 */
52static int cgroup_check_fs(struct thread_data *td)
53{
54	struct stat sb;
55	char tmp[256];
56
57	sprintf(tmp, "%s/tasks", td->o.cgroup_root);
58	return stat(tmp, &sb);
59}
60
61static char *get_cgroup_root(struct thread_data *td)
62{
63	char *str = malloc(64);
64
65	if (td->o.cgroup)
66		sprintf(str, "%s/%s", td->o.cgroup_root, td->o.cgroup);
67	else
68		sprintf(str, "%s/%s", td->o.cgroup_root, td->o.name);
69
70	return str;
71}
72
73static int write_int_to_file(struct thread_data *td, const char *path,
74			     const char *filename, unsigned int val,
75			     const char *onerr)
76{
77	char tmp[256];
78	FILE *f;
79
80	sprintf(tmp, "%s/%s", path, filename);
81	f = fopen(tmp, "w");
82	if (!f) {
83		td_verror(td, errno, onerr);
84		return 1;
85	}
86
87	fprintf(f, "%u", val);
88	fclose(f);
89	return 0;
90
91}
92
93static int cgroup_write_pid(struct thread_data *td, const char *root)
94{
95	unsigned int val = td->pid;
96
97	return write_int_to_file(td, root, "tasks", val, "cgroup write pid");
98}
99
100/*
101 * Move pid to root class
102 */
103static int cgroup_del_pid(struct thread_data *td)
104{
105	return cgroup_write_pid(td, td->o.cgroup_root);
106}
107
108int cgroup_setup(struct thread_data *td, struct flist_head *clist)
109{
110	char *root;
111
112	if (cgroup_check_fs(td)) {
113		log_err("fio: blkio cgroup mount point %s not valid\n",
114							td->o.cgroup_root);
115		return 1;
116	}
117
118	/*
119	 * Create container, if it doesn't exist
120	 */
121	root = get_cgroup_root(td);
122	if (mkdir(root, 0755) < 0) {
123		int __e = errno;
124
125		if (__e != EEXIST) {
126			td_verror(td, __e, "cgroup mkdir");
127			goto err;
128		}
129	} else
130		add_cgroup(root, clist);
131
132	if (td->o.cgroup_weight) {
133		if (write_int_to_file(td, root, "blkio.weight",
134					td->o.cgroup_weight,
135					"cgroup open weight"))
136			goto err;
137	}
138
139	if (!cgroup_write_pid(td, root)) {
140		free(root);
141		return 0;
142	}
143
144err:
145	free(root);
146	return 1;
147}
148
149void cgroup_shutdown(struct thread_data *td)
150{
151	if (cgroup_check_fs(td))
152		return;
153	if (!td->o.cgroup_weight && !td->o.cgroup)
154		return;
155
156	cgroup_del_pid(td);
157}
158
159static void fio_init cgroup_init(void)
160{
161	lock = fio_mutex_init(1);
162}
163
164static void fio_exit cgroup_exit(void)
165{
166	fio_mutex_remove(lock);
167}
168