1/*
2 * getrusage04 - accuracy of getrusage() with RUSAGE_THREAD
3 *
4 * This program is used for testing the following upstream commit:
5 * 761b1d26df542fd5eb348837351e4d2f3bc7bffe.
6 *
7 * getrusage() returns cpu resource usage with accuracy of 10ms
8 * when RUSAGE_THREAD is specified to the argument who. Meanwhile,
9 * accuracy is 1ms when RUSAGE_SELF is specified. This bad accuracy
10 * of getrusage() caused a big impact on some application which is
11 * critical to accuracy of cpu usage. The upstream fix removed
12 * casts to clock_t in task_u/stime(), to keep granularity of
13 * cputime_t over the calculation.
14 *
15 * Note that the accuracy on powerpc and s390x systems is always
16 * 10ms when either RUSAGE_THREAD or RUSAGE_SELF specified, so
17 * this test won't be executed on those platforms.
18 *
19 * Copyright (C) 2011  Red Hat, Inc.
20 * Copyright (C) 2013  Cyril Hrubis <chrubis@suse.cz>
21 *
22 * This program is free software; you can redistribute it and/or
23 * modify it under the terms of version 2 of the GNU General Public
24 * License as published by the Free Software Foundation.
25 *
26 * This program is distributed in the hope that it would be useful,
27 * but WITHOUT ANY WARRANTY; without even the implied warranty of
28 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
29 *
30 * Further, this software is distributed without any warranty that it
31 * is free of the rightful claim of any third person regarding
32 * infringement or the like.  Any license provided herein, whether
33 * implied or otherwise, applies only to this software file.  Patent
34 * licenses, if any, provided herein do not apply to combinations of
35 * this program with other software, or any other product whatsoever.
36 *
37 * You should have received a copy of the GNU General Public License
38 * along with this program; if not, write the Free Software
39 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
40 * 02110-1301, USA.
41 */
42
43#define _GNU_SOURCE
44#include <sys/types.h>
45#include <sys/resource.h>
46#include <sys/time.h>
47#include <errno.h>
48#include <stdio.h>
49#include <stdlib.h>
50#include <time.h>
51
52#include "test.h"
53#include "safe_macros.h"
54#include "lapi/posix_clocks.h"
55
56char *TCID = "getrusage04";
57int TST_TOTAL = 1;
58
59#define RECORD_MAX    20
60#define FACTOR_MAX    10
61
62#ifndef RUSAGE_THREAD
63#define RUSAGE_THREAD 1
64#endif
65
66static long BIAS_MAX;
67
68static int opt_factor;
69static char *factor_str;
70static long factor_nr = 1;
71
72option_t child_options[] = {
73	{"m:", &opt_factor, &factor_str},
74	{NULL, NULL, NULL}
75};
76
77static void fusage(void);
78static void busyloop(long wait);
79static void setup(void);
80static void cleanup(void);
81
82int main(int argc, char *argv[])
83{
84	struct rusage usage;
85	unsigned long ulast, udelta, slast, sdelta;
86	int i, lc;
87	char msg_string[BUFSIZ];
88
89	tst_parse_opts(argc, argv, child_options, fusage);
90
91#if (__powerpc__) || (__powerpc64__) || (__s390__) || (__s390x__)
92	tst_brkm(TCONF, NULL, "This test is not designed for current system");
93#endif
94
95	setup();
96
97	if (opt_factor)
98		factor_nr = SAFE_STRTOL(cleanup, factor_str, 0, FACTOR_MAX);
99
100	tst_resm(TINFO, "Using %ld as multiply factor for max [us]time "
101		 "increment (1000+%ldus)!", factor_nr, BIAS_MAX * factor_nr);
102
103	for (lc = 0; TEST_LOOPING(lc); lc++) {
104		tst_count = 0;
105		i = 0;
106		SAFE_GETRUSAGE(cleanup, RUSAGE_THREAD, &usage);
107		tst_resm(TINFO, "utime:%12lldus; stime:%12lldus",
108			 (long long)usage.ru_utime.tv_usec,
109			 (long long)usage.ru_stime.tv_usec);
110		ulast = usage.ru_utime.tv_usec;
111		slast = usage.ru_stime.tv_usec;
112
113		while (i < RECORD_MAX) {
114			SAFE_GETRUSAGE(cleanup, RUSAGE_THREAD, &usage);
115			udelta = usage.ru_utime.tv_usec - ulast;
116			sdelta = usage.ru_stime.tv_usec - slast;
117			if (udelta > 0 || sdelta > 0) {
118				i++;
119				tst_resm(TINFO, "utime:%12lldus; stime:%12lldus",
120					 (long long)usage.ru_utime.tv_usec,
121					 (long long)usage.ru_stime.tv_usec);
122				if ((long)udelta > 1000 + (BIAS_MAX * factor_nr)) {
123					sprintf(msg_string,
124						"utime increased > %ldus:",
125						1000 + BIAS_MAX * factor_nr);
126					tst_brkm(TFAIL, cleanup, msg_string,
127						 " delta = %luus", udelta);
128				}
129				if ((long)sdelta > 1000 + (BIAS_MAX * factor_nr)) {
130					sprintf(msg_string,
131						"stime increased > %ldus:",
132						1000 + BIAS_MAX * factor_nr);
133					tst_brkm(TFAIL, cleanup, msg_string,
134						 " delta = %luus", sdelta);
135				}
136			}
137			ulast = usage.ru_utime.tv_usec;
138			slast = usage.ru_stime.tv_usec;
139			busyloop(100000);
140		}
141	}
142
143	tst_resm(TPASS, "Test Passed");
144
145	cleanup();
146	tst_exit();
147}
148
149static void fusage(void)
150{
151	printf("  -m n    use n as multiply factor for max [us]time "
152	       "increment (1000+(1000*n)us),\n          default value is 1\n");
153}
154
155static void busyloop(long wait)
156{
157	while (wait--) ;
158}
159
160/*
161 * The resolution of getrusage timers currently depends on CONFIG_HZ settings,
162 * as they are measured in jiffies.
163 *
164 * The problem is that there is no reasonable API to get either getrusage
165 * timers resolution or duration of jiffie.
166 *
167 * Here we use clock_getres() with linux specific CLOCK_REALTIME_COARSE (added
168 * in 2.6.32) which is also based on jiffies. This timer has the same
169 * granularity as getrusage but it's not guaranteed and it may change in the
170 * future.
171 *
172 * The default value for resolution was choosen to be 4ms as it corresponds to
173 * CONFIG_HZ=250 which seems to be default value.
174 */
175static unsigned long guess_timer_resolution(void)
176{
177	struct timespec res;
178
179	if (clock_getres(CLOCK_REALTIME_COARSE, &res)) {
180		tst_resm(TINFO,
181		        "CLOCK_REALTIME_COARSE not supported, using 4000 us");
182		return 4000;
183	}
184
185	if (res.tv_nsec < 1000000 || res.tv_nsec > 10000000) {
186		tst_resm(TINFO, "Unexpected CLOCK_REALTIME_COARSE resolution,"
187		        " using 4000 us");
188		return 4000;
189	}
190
191	tst_resm(TINFO, "Expected timers granularity is %li us",
192	         res.tv_nsec / 1000);
193
194	return res.tv_nsec / 1000;
195}
196
197static void setup(void)
198{
199	tst_sig(NOFORK, DEF_HANDLER, cleanup);
200
201	if (tst_is_virt(VIRT_XEN) || tst_is_virt(VIRT_KVM) || tst_is_virt(VIRT_HYPERV))
202		tst_brkm(TCONF, NULL, "This testcase is not supported on this"
203		        " virtual machine.");
204
205	BIAS_MAX = guess_timer_resolution();
206
207	TEST_PAUSE;
208}
209
210static void cleanup(void)
211{
212}
213