Step 5 - Dynamic and typed parameters #607
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…ype::NumericType``
…load if there's only one visitor i.e. no overload!
…ariables require queues and of variable locations. Encapsulated variable location logic in little class and tidied various bits
* added simple DynamicParameterContainer class
… and rethrow runtime error
…untime implementation * Moved data structures into GeNN::Runtime::MergedDynamicFieldDestinations (as much to make it possible to forward declare as anything else) * Made reference to runtime passed through to GroupMerged::GetFieldValueFunc non-const * Added a third variant of GroupMerged::FieldValue which returns a value AND an associated MergedDynamicFieldDestinations * Used to implement parameters in environment
…pdate and weight update
…esult in exception on test_pre_post_neuron_vars
neworderofjamie
changed the title
* reinstated logic to ignore READWRITE access to non-batched variables if custom update is batched but batch size = 1 * fixed bug in preoutput update
neworderofjamie
changed the title
tnowotny
approved these changes
Jan 8, 2024
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'Traditionally', in GeNN if you wanted to make parameters changable at runtime you had to change them to extra global parameters. Before GeNN 4.3.0, this used to be pretty efficient as they were all passed through to the device using kernel parameters (which are effectively implemented as a big block of constant cache). However, since adding the whole merging system way back in GeNN 4.3.0, this hasn't been possible so, for backward compatibility, they have been manually copied every timestep as there's no way to know when they change. Because they're very small and there are potentially lots of them this can be very inefficient. This functionality was totally removed in this trail of PRs but here we implement its replacement - dynamic parameters! Key things are:
pop.set_param_dynamic("r0")pop.set_dynamic_param_value("r0", current_r0)Another issue with parameters is that they didn't previously have a type. This meant in extreme cases where you have a model with lots of heterogeneous integer parameters (so the conversion couldn't be done at compile time) e.g. a big convnet with different types of convolution implemented as Toeplitz connectivity init snippets, you could actually overload the GPU special function unit just through converting all the parameters passed as
scalartoint. Also,scalaris typically a 32-bit float so cannot represent the full range of a 32-bit integer. Fixing this wasn't particularly difficult, just required passing types through from theParamValuesto the parameters. However you need to be able to specify parameters in some way and, back in #595, I addedNumericValuewhich is now exposed to python and, in this PR, used for just this.Fear not, there is only one step to go until we have something resembling a release candidate!