Built-in timers¶
Basic timers¶
Basic built-in timers keep track of the time NEST spent for network construction and actual simulation (propagation of the network state). These timers are active in all simulations with NEST, and the measured times can be checked by querying the corresponding kernel attributes. For example:
nest.time_simulate
The following basic time measurements are available:
Name |
Explanation |
---|---|
|
Cumulative time NEST spent creating neurons and devices |
|
Cumulative time NEST spent creating connections |
|
Time NEST spent in the last
|
Note
While preparing the actual simulation after network construction,
NEST needs to build the pre-synaptic part of the connection
infrastructure, which requires MPI communication (Jordan et
al. 2018). This
happens only for the first call to Simulate()
unless
connectivity changed in the meantime, and it may cause significant
overhead by adding to time_simulate
. Therefore, the cumulative
time NEST spent for building the pre-synaptic connection
infrastructure is also tracked by a basic timer and available as
kernel attribute time_communicate_prepare
.
In the context of NEST performance monitoring, other useful kernel attributes are:
Name |
Explanation |
---|---|
|
Cumulative simulated time |
|
Number of spikes emitted by the
neurons represented on this MPI
rank during the last
|
Note
nest.ResetKernel()
resets all time measurements as well as
biological_time
and local_spike_counter
.
Detailed timers¶
Detailed built-in timers can be activated (and again deactivated)
prior to compilation through the CMake flag
-Dwith-detailed-timers=ON
. They provide further insights into the
time NEST spends in different phases of the simulation cycle, but they
can impact the runtime. Therefore, detailed timers are by default
inactive.
If detailed timers are active, the following time measurements are available as kernel attributes:
Name |
Explanation |
Part of |
---|---|---|
|
Cumulative time for communicating connection information from postsynaptic to presynaptic side |
|
|
Cumulative time for core MPI communication when gathering target data |
|
|
Time for neuron update |
|
|
Time for complete spike exchange after update phase |
|
|
Time to collocate MPI send buffer from spike register |
|
|
Time for communicating spikes between compute nodes |
|
|
Time to deliver events from the MPI receive buffers to their local synaptic targets (including synaptic update, e.g. STDP synapses) and to the spike ring buffers of the corresponding postsynaptic neurons |
|