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backend to "switch" to a different net for the endgame #1968

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@borg323 borg323 commented Mar 6, 2024

The net is switched when the number of pieces on board, excluding pawns and kings, reaches a threshold, 6 by default. The net to switch to is selected using the endgame_weights backend option. Also two subdictionaries are accepted in the backend options, namely main and endgame to allow using different backend options with the respective net. Unsurprisingly, the threshold is set using the threshold backend option.

@@ -124,6 +124,13 @@ class Lexer {
static const std::string kNumberChars = "0123456789-.";
if (kNumberChars.find(str_[idx_]) != std::string::npos) {
ReadNumber();
// If the next character isn't a separator, this is probably an identifier
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Maybe IsAlpha() would work better? Otherwise we'd need to remember to check for more characters here if we extend the syntax.

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The problem I'm trying to address here is that strings starting with a number (e.g. a typical net name like 744204.pb.gz) are identified as a number and parsing fails at the first unexpected character - it is easier to blacklist a couple of characters than to whitelist dozens.


class SwitchComputation : public NetworkComputation {
public:
SwitchComputation(std::unique_ptr<NetworkComputation> main_comp,
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(totally optional)
I'd do it more generic, with a vector of computation+thresholds..


void ComputeBlocking() override {
if (threads_ > 1 && main_cnt_ > 0 && endgame_cnt_ > 0) {
std::thread main(
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Note that starting a thread is usually slow, especially on linux.
In other backends, e.g. network_mux.cc we did condvar-based synchronization instead.

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This is to test the waters. If it shows potential we can consider a better performing threading approach. (Note the default it one thread and I didn't mention it in the description).

int GetBatchSize() const override { return main_cnt_ + endgame_cnt_; }

float GetQVal(int sample) const override {
if (is_endgame_[sample]) {
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Maybe helper function

NetworkComputation* GetComp(int sample) { return is_endgame_[sample] ? endgame_comp : main_comp_; }

?

const OptionsDict& options) {
auto backends = NetworkFactory::Get()->GetBackendsList();

threshold_ = options.GetOrDefault<int>("threshold", 6);
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Without looking into the code, neither variable nor the parameter name's meaning "threshold" was clear. Maybe something with pieces in the name? pieces_threshold? piece_count? :-\ Not sure what would be better though.

}

bool IsCpu() const override {
return main_net_->GetMiniBatchSize() | endgame_net_->GetMiniBatchSize();
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IsCpu()

src/neural/network_blend.cc Outdated Show resolved Hide resolved
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2 participants