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timestep command

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Syntax

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timers args
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  • args = one or more of off or loop or normal or full or sync or nosync
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+off = do not collect and print timing information
+loop = collect only the total time for the simulation loop
+normal = collect timer information broken down in sections (default)
+full = like normal but also include CPU and thread utilzation
+sync = explicitly synchronize MPI tasks between sections
+nosync = do not synchronize MPI tasks when collecting timer info (default)
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Examples

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timers full sync
+timers loop
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Description

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Select to which level of detail LAMMPS is performing internal profiling.

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During regular runs LAMMPS will collect information about how much time is +spent in different sections of the code and thus can provide valuable +information for determining performance and load imbalance problems. This +can be done at different levels of detail and accuracy. For more +information about the timing output, please have a look at the discussion of screen output.

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The off setting will turn all time measurements off. The loop setting +will only measure the total time of run loop and not collect any detailed +per section information. With the normal setting, timing information for +individual sections of the code are collected and also information about +load imbalances inside those sections presented. The full setting adds +information about CPU utilization and thread utilization, when multi-threading +is enabled.

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With the sync setting, all MPI tasks are synchronized at each timer call +and thus allowing to study load imbalance more accuractly, but this usually +has some performance impact. Using the nosync setting this can be turned +off (which is the default).

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Multiple keywords can be provided and for keywords that are mutually +exclusive, the last one in that group is taking effect.

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Warning

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Using the full and sync options provides the most +detailed and accurate timing information, but also can have a significant +negative performance impact due to the overhead of the many required system +calls. It is thus recommended to use these settings only when making tests +to identify the performance. For calculations with few atoms or a very +large number of performance, even using the normal setting can have +a measurable performance impact. It is recommended in those cases to use +the loop or off setting.

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Restrictions

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none
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Default

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timers normal nosync

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