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37 #include "gmxpre.h"
38
39 #include "walltime_accounting.h"
40
41 #include "config.h"
42
43 #include <ctime>
44
45 #ifdef HAVE_UNISTD_H
46 # include <unistd.h>
47 #endif
48 #ifdef HAVE_SYS_TIME_H
49 # include <sys/time.h>
50 #endif
51
52 #include "gromacs/utility/basedefinitions.h"
53 #include "gromacs/utility/smalloc.h"
54
55 /* TODO in future: convert gmx_walltime_accounting to a class,
56 * resolve who should have responsibility for recording the number of
57 * steps done, consider whether parts of finish_time, print_perf,
58 * wallcycle_print belong in this module.
59 *
60 * If/when any kind of task parallelism is implemented (even OpenMP
61 * regions simultaneously assigned to different tasks), consider
62 * whether this data structure (and/or cycle counters) should be
63 * maintained on a per-OpenMP-thread basis.
64 *
65 * Consider also replacing this with std::chrono. */
66
67 /*! \brief Manages caching wall-clock time measurements for
68 * simulations */
69 typedef struct gmx_walltime_accounting
70 {
71 //! Seconds since the epoch recorded at the start of the simulation
72 double start_time_stamp;
73 /*! \brief Seconds since the epoch recorded at the reset of
74 * counters for the simulation (or the start, if no reset has
75 * occured). */
76 double reset_time_stamp;
77 /*! \brief Seconds since the epoch recorded at the reset of
78 * counters for the simulation for this thread (or the start, if
79 * no reset has occured). */
80 double reset_time_stamp_per_thread;
81 //! Total seconds elapsed over the simulation since counter reset
82 double elapsed_time;
83 //! Total seconds elapsed over the simulation since counter reset running this thread
84 double elapsed_time_over_all_threads;
85 /*! \brief Number of OpenMP threads that will be launched by this
86 * MPI rank.
87 *
88 * This is used to scale elapsed_time_over_all_threads so
89 * that any combination of real MPI, thread MPI and OpenMP (even
90 * mdrun -ntomp_pme) processes/threads would (when run at maximum
91 * efficiency) return values such that the sum of
92 * elapsed_time_over_all_threads over all threads was constant
93 * with respect to parallelism implementation. */
94 int numOpenMPThreads;
95 //! Numbers of steps done before reset of counters
96 int64_t nsteps_done_at_reset;
97 //! Set by integrators to report the amount of work they did
98 int64_t nsteps_done;
99 //! Whether the simulation has finished in a way valid for walltime reporting.
100 bool isValidFinish;
101 } t_gmx_walltime_accounting;
102
103 /*! \brief Calls system timing routines (e.g. clock_gettime) to get
104 * the (fractional) number of seconds elapsed since the epoch when
105 * this thread was executing.
106 *
107 * This can be used to measure system load. This can be unreliable if
108 * threads migrate between sockets. If thread-specific timers are not
109 * supported by the OS (e.g. if the OS is not POSIX-compliant), this
110 * function is implemented by gmx_gettime. */
111 static double gmx_gettime_per_thread();
112
113 // TODO In principle, all this should get protected by checks that
114 // walltime_accounting is not nullptr. In practice, that nullptr condition
115 // does not happen, and future refactoring will likely enforce it by
116 // having the gmx_walltime_accounting_t object be owned by the runner
117 // object. When these become member functions, existence will be
118 // guaranteed.
119
walltime_accounting_init(int numOpenMPThreads)120 gmx_walltime_accounting_t walltime_accounting_init(int numOpenMPThreads)
121 {
122 gmx_walltime_accounting_t walltime_accounting;
123
124 snew(walltime_accounting, 1);
125 walltime_accounting->start_time_stamp = 0;
126 walltime_accounting->reset_time_stamp = 0;
127 walltime_accounting->reset_time_stamp_per_thread = 0;
128 walltime_accounting->elapsed_time = 0;
129 walltime_accounting->nsteps_done_at_reset = 0;
130 walltime_accounting->nsteps_done = 0;
131 walltime_accounting->numOpenMPThreads = numOpenMPThreads;
132 walltime_accounting->isValidFinish = false;
133
134 return walltime_accounting;
135 }
136
walltime_accounting_destroy(gmx_walltime_accounting_t walltime_accounting)137 void walltime_accounting_destroy(gmx_walltime_accounting_t walltime_accounting)
138 {
139 sfree(walltime_accounting);
140 }
141
walltime_accounting_reset_time(gmx_walltime_accounting_t walltime_accounting,int64_t step)142 void walltime_accounting_reset_time(gmx_walltime_accounting_t walltime_accounting, int64_t step)
143 {
144 walltime_accounting->reset_time_stamp = gmx_gettime();
145 walltime_accounting->reset_time_stamp_per_thread = gmx_gettime_per_thread();
146 walltime_accounting->elapsed_time = 0;
147 walltime_accounting->nsteps_done = 0;
148 walltime_accounting->nsteps_done_at_reset = step;
149 }
150
walltime_accounting_start_time(gmx_walltime_accounting_t walltime_accounting)151 void walltime_accounting_start_time(gmx_walltime_accounting_t walltime_accounting)
152 {
153 walltime_accounting_reset_time(walltime_accounting, 0);
154 walltime_accounting->start_time_stamp = walltime_accounting->reset_time_stamp;
155 }
156
walltime_accounting_end_time(gmx_walltime_accounting_t walltime_accounting)157 void walltime_accounting_end_time(gmx_walltime_accounting_t walltime_accounting)
158 {
159 double now, now_per_thread;
160
161 now = gmx_gettime();
162 now_per_thread = gmx_gettime_per_thread();
163
164 walltime_accounting->elapsed_time = now - walltime_accounting->reset_time_stamp;
165 walltime_accounting->elapsed_time_over_all_threads =
166 now_per_thread - walltime_accounting->reset_time_stamp_per_thread;
167 /* For thread-MPI, the per-thread CPU timer makes this just
168 * work. For OpenMP threads, the per-thread CPU timer measurement
169 * needs to be multiplied by the number of OpenMP threads used,
170 * under the current assumption that all regions ever opened
171 * within a process are of the same size, and each thread should
172 * keep one core busy.
173 */
174 walltime_accounting->elapsed_time_over_all_threads *= walltime_accounting->numOpenMPThreads;
175 }
176
walltime_accounting_get_time_since_start(gmx_walltime_accounting_t walltime_accounting)177 double walltime_accounting_get_time_since_start(gmx_walltime_accounting_t walltime_accounting)
178 {
179 return gmx_gettime() - walltime_accounting->start_time_stamp;
180 }
181
walltime_accounting_get_time_since_reset(gmx_walltime_accounting_t walltime_accounting)182 double walltime_accounting_get_time_since_reset(gmx_walltime_accounting_t walltime_accounting)
183 {
184 return gmx_gettime() - walltime_accounting->reset_time_stamp;
185 }
186
walltime_accounting_get_time_since_reset_over_all_threads(gmx_walltime_accounting_t walltime_accounting)187 double walltime_accounting_get_time_since_reset_over_all_threads(gmx_walltime_accounting_t walltime_accounting)
188 {
189 return walltime_accounting->elapsed_time_over_all_threads;
190 }
191
walltime_accounting_get_start_time_stamp(gmx_walltime_accounting_t walltime_accounting)192 double walltime_accounting_get_start_time_stamp(gmx_walltime_accounting_t walltime_accounting)
193 {
194 return walltime_accounting->start_time_stamp;
195 }
196
walltime_accounting_get_nsteps_done_since_reset(gmx_walltime_accounting_t walltime_accounting)197 int64_t walltime_accounting_get_nsteps_done_since_reset(gmx_walltime_accounting_t walltime_accounting)
198 {
199 return walltime_accounting->nsteps_done - walltime_accounting->nsteps_done_at_reset;
200 }
201
walltime_accounting_set_nsteps_done(gmx_walltime_accounting_t walltime_accounting,int64_t nsteps_done)202 void walltime_accounting_set_nsteps_done(gmx_walltime_accounting_t walltime_accounting, int64_t nsteps_done)
203 {
204 walltime_accounting->nsteps_done = nsteps_done;
205 }
206
gmx_gettime()207 double gmx_gettime()
208 {
209 /* Use clock_gettime only if we know linking the C run-time
210 library will work (which is not trivial on e.g. Crays), and its
211 headers claim sufficient support for POSIX (ie not Mac and
212 Windows). */
213 #if HAVE_CLOCK_GETTIME && defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0
214 struct timespec t;
215 double seconds;
216
217 clock_gettime(CLOCK_REALTIME, &t);
218 seconds = static_cast<double>(t.tv_sec) + 1e-9 * t.tv_nsec;
219
220 return seconds;
221 #elif HAVE_GETTIMEOFDAY
222 // Note that gettimeofday() is deprecated by POSIX, but since Mac
223 // and Windows do not yet support POSIX, we are still stuck.
224 struct timeval t;
225 double seconds;
226
227 gettimeofday(&t, nullptr);
228 seconds = static_cast<double>(t.tv_sec) + 1e-6 * t.tv_usec;
229
230 return seconds;
231 #else
232 double seconds;
233
234 seconds = time(nullptr);
235
236 return seconds;
237 #endif
238 }
239
walltime_accounting_set_valid_finish(gmx_walltime_accounting_t walltime_accounting)240 void walltime_accounting_set_valid_finish(gmx_walltime_accounting_t walltime_accounting)
241 {
242 walltime_accounting->isValidFinish = true;
243 }
244
245 //! Return whether the simulation finished in a way valid for reporting walltime.
walltime_accounting_get_valid_finish(const gmx_walltime_accounting * walltime_accounting)246 bool walltime_accounting_get_valid_finish(const gmx_walltime_accounting* walltime_accounting)
247 {
248 return walltime_accounting->isValidFinish;
249 }
250
gmx_gettime_per_thread()251 static double gmx_gettime_per_thread()
252 {
253 /* Use clock_gettime only if we know linking the C run-time
254 library will work (which is not trivial on e.g. Crays), and its
255 headers claim sufficient support for POSIX (ie not Mac and
256 Windows). */
257 #if HAVE_CLOCK_GETTIME && defined(_POSIX_THREAD_CPUTIME) && _POSIX_THREAD_CPUTIME > 0
258 struct timespec t;
259 double seconds;
260
261 clock_gettime(CLOCK_THREAD_CPUTIME_ID, &t);
262 seconds = static_cast<double>(t.tv_sec) + 1e-9 * t.tv_nsec;
263
264 return seconds;
265 #else
266 return gmx_gettime();
267 #endif
268 }
269