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38 #include "walltime_accounting.h"
47 #ifdef HAVE_SYS_TIME_H
48 # include <sys/time.h>
51 #include "gromacs/utility/basedefinitions.h"
52 #include "gromacs/utility/smalloc.h"
54 /* TODO in future: convert gmx_walltime_accounting to a class,
55 * resolve who should have responsibility for recording the number of
56 * steps done, consider whether parts of finish_time, print_perf,
57 * wallcycle_print belong in this module.
59 * If/when any kind of task parallelism is implemented (even OpenMP
60 * regions simultaneously assigned to different tasks), consider
61 * whether this data structure (and/or cycle counters) should be
62 * maintained on a per-OpenMP-thread basis.
64 * Consider also replacing this with std::chrono. */
66 /*! \brief Manages caching wall-clock time measurements for
68 typedef struct gmx_walltime_accounting
70 //! Seconds since the epoch recorded at the start of the simulation
71 double start_time_stamp;
72 /*! \brief Seconds since the epoch recorded at the reset of
73 * counters for the simulation (or the start, if no reset has
75 double reset_time_stamp;
76 /*! \brief Seconds since the epoch recorded at the reset of
77 * counters for the simulation for this thread (or the start, if
78 * no reset has occured). */
79 double reset_time_stamp_per_thread;
80 //! Total seconds elapsed over the simulation since counter reset
82 //! Total seconds elapsed over the simulation since counter reset running this thread
83 double elapsed_time_over_all_threads;
84 /*! \brief Number of OpenMP threads that will be launched by this
87 * This is used to scale elapsed_time_over_all_threads so
88 * that any combination of real MPI, thread MPI and OpenMP (even
89 * mdrun -ntomp_pme) processes/threads would (when run at maximum
90 * efficiency) return values such that the sum of
91 * elapsed_time_over_all_threads over all threads was constant
92 * with respect to parallelism implementation. */
94 //! Numbers of steps done before reset of counters
95 int64_t nsteps_done_at_reset;
96 //! Set by integrators to report the amount of work they did
98 //! Whether the simulation has finished in a way valid for walltime reporting.
100 } t_gmx_walltime_accounting;
102 /*! \brief Calls system timing routines (e.g. clock_gettime) to get
103 * the (fractional) number of seconds elapsed since the epoch when
104 * this thread was executing.
106 * This can be used to measure system load. This can be unreliable if
107 * threads migrate between sockets. If thread-specific timers are not
108 * supported by the OS (e.g. if the OS is not POSIX-compliant), this
109 * function is implemented by gmx_gettime. */
110 static double gmx_gettime_per_thread();
112 // TODO In principle, all this should get protected by checks that
113 // walltime_accounting is not nullptr. In practice, that nullptr condition
114 // does not happen, and future refactoring will likely enforce it by
115 // having the gmx_walltime_accounting_t object be owned by the runner
116 // object. When these become member functions, existence will be
119 gmx_walltime_accounting_t walltime_accounting_init(int numOpenMPThreads)
121 gmx_walltime_accounting_t walltime_accounting;
123 snew(walltime_accounting, 1);
124 walltime_accounting->start_time_stamp = 0;
125 walltime_accounting->reset_time_stamp = 0;
126 walltime_accounting->reset_time_stamp_per_thread = 0;
127 walltime_accounting->elapsed_time = 0;
128 walltime_accounting->nsteps_done_at_reset = 0;
129 walltime_accounting->nsteps_done = 0;
130 walltime_accounting->numOpenMPThreads = numOpenMPThreads;
131 walltime_accounting->isValidFinish = false;
133 return walltime_accounting;
136 void walltime_accounting_destroy(gmx_walltime_accounting_t walltime_accounting)
138 sfree(walltime_accounting);
141 void walltime_accounting_reset_time(gmx_walltime_accounting_t walltime_accounting, int64_t step)
143 walltime_accounting->reset_time_stamp = gmx_gettime();
144 walltime_accounting->reset_time_stamp_per_thread = gmx_gettime_per_thread();
145 walltime_accounting->elapsed_time = 0;
146 walltime_accounting->nsteps_done = 0;
147 walltime_accounting->nsteps_done_at_reset = step;
150 void walltime_accounting_start_time(gmx_walltime_accounting_t walltime_accounting)
152 walltime_accounting_reset_time(walltime_accounting, 0);
153 walltime_accounting->start_time_stamp = walltime_accounting->reset_time_stamp;
156 void walltime_accounting_end_time(gmx_walltime_accounting_t walltime_accounting)
158 double now, now_per_thread;
161 now_per_thread = gmx_gettime_per_thread();
163 walltime_accounting->elapsed_time = now - walltime_accounting->reset_time_stamp;
164 walltime_accounting->elapsed_time_over_all_threads =
165 now_per_thread - walltime_accounting->reset_time_stamp_per_thread;
166 /* For thread-MPI, the per-thread CPU timer makes this just
167 * work. For OpenMP threads, the per-thread CPU timer measurement
168 * needs to be multiplied by the number of OpenMP threads used,
169 * under the current assumption that all regions ever opened
170 * within a process are of the same size, and each thread should
171 * keep one core busy.
173 walltime_accounting->elapsed_time_over_all_threads *= walltime_accounting->numOpenMPThreads;
176 double walltime_accounting_get_time_since_start(gmx_walltime_accounting_t walltime_accounting)
178 return gmx_gettime() - walltime_accounting->start_time_stamp;
181 double walltime_accounting_get_time_since_reset(gmx_walltime_accounting_t walltime_accounting)
183 return gmx_gettime() - walltime_accounting->reset_time_stamp;
186 double walltime_accounting_get_time_since_reset_over_all_threads(gmx_walltime_accounting_t walltime_accounting)
188 return walltime_accounting->elapsed_time_over_all_threads;
191 double walltime_accounting_get_start_time_stamp(gmx_walltime_accounting_t walltime_accounting)
193 return walltime_accounting->start_time_stamp;
196 int64_t walltime_accounting_get_nsteps_done_since_reset(gmx_walltime_accounting_t walltime_accounting)
198 return walltime_accounting->nsteps_done - walltime_accounting->nsteps_done_at_reset;
201 void walltime_accounting_set_nsteps_done(gmx_walltime_accounting_t walltime_accounting, int64_t nsteps_done)
203 walltime_accounting->nsteps_done = nsteps_done;
208 /* Use clock_gettime only if we know linking the C run-time
209 library will work (which is not trivial on e.g. Crays), and its
210 headers claim sufficient support for POSIX (ie not Mac and
212 #if HAVE_CLOCK_GETTIME && defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0
216 clock_gettime(CLOCK_REALTIME, &t);
217 seconds = static_cast<double>(t.tv_sec) + 1e-9 * t.tv_nsec;
220 #elif HAVE_GETTIMEOFDAY
221 // Note that gettimeofday() is deprecated by POSIX, but since Mac
222 // and Windows do not yet support POSIX, we are still stuck.
226 gettimeofday(&t, nullptr);
227 seconds = static_cast<double>(t.tv_sec) + 1e-6 * t.tv_usec;
233 seconds = time(nullptr);
239 void walltime_accounting_set_valid_finish(gmx_walltime_accounting_t walltime_accounting)
241 walltime_accounting->isValidFinish = true;
244 //! Return whether the simulation finished in a way valid for reporting walltime.
245 bool walltime_accounting_get_valid_finish(const gmx_walltime_accounting* walltime_accounting)
247 return walltime_accounting->isValidFinish;
250 static double gmx_gettime_per_thread()
252 /* Use clock_gettime only if we know linking the C run-time
253 library will work (which is not trivial on e.g. Crays), and its
254 headers claim sufficient support for POSIX (ie not Mac and
256 #if HAVE_CLOCK_GETTIME && defined(_POSIX_THREAD_CPUTIME) && _POSIX_THREAD_CPUTIME > 0
260 clock_gettime(CLOCK_THREAD_CPUTIME_ID, &t);
261 seconds = static_cast<double>(t.tv_sec) + 1e-9 * t.tv_nsec;
265 return gmx_gettime();