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34 #include "gromacs/timing/walltime_accounting.h"
40 #include "gromacs/legacyheaders/smalloc.h"
41 #include "gromacs/legacyheaders/types/simple.h"
47 #ifdef HAVE_SYS_TIME_H
51 /* TODO in future: convert gmx_walltime_accounting to a class,
52 * resolve who should have responsibility for recording the number of
53 * steps done, consider whether parts of finish_time, print_perf,
54 * wallcycle_print belong in this module.
56 * If/when any kind of task parallelism is implemented (even OpenMP
57 * regions simultaneously assigned to different tasks), consider
58 * whether this data structure (and/or cycle counters) should be
59 * maintained on a per-OpenMP-thread basis. */
61 /*! \brief Manages caching wall-clock time measurements for
63 typedef struct gmx_walltime_accounting {
64 //! Seconds since the epoch recorded at the start of the simulation
65 double start_time_stamp;
66 //! Seconds since the epoch recorded at the start of the simulation for this thread
67 double start_time_stamp_per_thread;
68 //! Total seconds elapsed over the simulation
70 //! Total seconds elapsed over the simulation running this thread
71 double elapsed_time_over_all_threads;
72 /*! \brief Number of OpenMP threads that will be launched by this
75 * This is used to scale elapsed_time_over_all_threads so
76 * that any combination of real MPI, thread MPI and OpenMP (even
77 * mdrun -ntomp_pme) processes/threads would (when run at maximum
78 * efficiency) return values such that the sum of
79 * elapsed_time_over_all_threads over all threads was constant
80 * with respect to parallelism implementation. */
82 //! Set by integrators to report the amount of work they did
83 gmx_large_int_t nsteps_done;
84 } t_gmx_walltime_accounting;
86 /*! \brief Calls system timing routines (e.g. clock_gettime) to get
87 * the (fractional) number of seconds elapsed since the epoch when
88 * this thread was executing.
90 * This can be used to measure system load. This can be unreliable if
91 * threads migrate between sockets. If thread-specific timers are not
92 * supported by the OS (e.g. if the OS is not POSIX-compliant), this
93 * function is implemented by gmx_gettime. */
94 static double gmx_gettime_per_thread();
96 // TODO In principle, all this should get protected by checks that
97 // walltime_accounting is not null. In practice, that NULL condition
98 // does not happen, and future refactoring will likely enforce it by
99 // having the gmx_walltime_accounting_t object be owned by the runner
100 // object. When these become member functions, existence will be
103 gmx_walltime_accounting_t
104 walltime_accounting_init(int numOpenMPThreads)
106 gmx_walltime_accounting_t walltime_accounting;
108 snew(walltime_accounting, 1);
109 walltime_accounting->start_time_stamp = 0;
110 walltime_accounting->start_time_stamp_per_thread = 0;
111 walltime_accounting->elapsed_time = 0;
112 walltime_accounting->nsteps_done = 0;
113 walltime_accounting->numOpenMPThreads = numOpenMPThreads;
115 return walltime_accounting;
119 walltime_accounting_destroy(gmx_walltime_accounting_t walltime_accounting)
121 sfree(walltime_accounting);
125 walltime_accounting_start(gmx_walltime_accounting_t walltime_accounting)
127 walltime_accounting->start_time_stamp = gmx_gettime();
128 walltime_accounting->start_time_stamp_per_thread = gmx_gettime_per_thread();
129 walltime_accounting->elapsed_time = 0;
130 walltime_accounting->nsteps_done = 0;
134 walltime_accounting_end(gmx_walltime_accounting_t walltime_accounting)
136 double now, now_per_thread;
139 now_per_thread = gmx_gettime_per_thread();
141 walltime_accounting->elapsed_time = now - walltime_accounting->start_time_stamp;
142 walltime_accounting->elapsed_time_over_all_threads = now_per_thread - walltime_accounting->start_time_stamp_per_thread;
143 /* For thread-MPI, the per-thread CPU timer makes this just
144 * work. For OpenMP threads, the per-thread CPU timer measurement
145 * needs to be multiplied by the number of OpenMP threads used,
146 * under the current assumption that all regions ever opened
147 * within a process are of the same size, and each thread should
148 * keep one core busy.
150 walltime_accounting->elapsed_time_over_all_threads *= walltime_accounting->numOpenMPThreads;
154 walltime_accounting_get_current_elapsed_time(gmx_walltime_accounting_t walltime_accounting)
156 return gmx_gettime() - walltime_accounting->start_time_stamp;
160 walltime_accounting_get_elapsed_time(gmx_walltime_accounting_t walltime_accounting)
162 return walltime_accounting->elapsed_time;
166 walltime_accounting_get_elapsed_time_over_all_threads(gmx_walltime_accounting_t walltime_accounting)
168 return walltime_accounting->elapsed_time_over_all_threads;
172 walltime_accounting_get_start_time_stamp(gmx_walltime_accounting_t walltime_accounting)
174 return walltime_accounting->start_time_stamp;
178 walltime_accounting_get_nsteps_done(gmx_walltime_accounting_t walltime_accounting)
180 return walltime_accounting->nsteps_done;
184 walltime_accounting_set_nsteps_done(gmx_walltime_accounting_t walltime_accounting,
185 gmx_large_int_t nsteps_done)
187 walltime_accounting->nsteps_done = nsteps_done;
193 #if defined HAVE_CLOCK_GETTIME && _POSIX_TIMERS >= 0
194 /* Mac and Windows do not support this. For added fun, Windows
195 * defines _POSIX_TIMERS without actually providing the
200 clock_gettime(CLOCK_REALTIME, &t);
201 seconds = (double) t.tv_sec + 1e-9*(double)t.tv_nsec;
204 #elif defined HAVE_GETTIMEOFDAY
205 // Note that gettimeofday() is deprecated by POSIX, but since Mac
206 // and Windows do not yet support POSIX, we are still stuck.
210 gettimeofday(&t, NULL);
211 seconds = (double) t.tv_sec + 1e-6*(double)t.tv_usec;
217 seconds = time(NULL);
224 gmx_gettime_per_thread()
226 #if defined HAVE_CLOCK_GETTIME && _POSIX_THREAD_CPUTIME >= 0
230 clock_gettime(CLOCK_THREAD_CPUTIME_ID, &t);
231 seconds = (double) t.tv_sec + 1e-9*(double)t.tv_nsec;
235 return gmx_gettime();