multiple gpu support (and option to use less than maximum cpu threads)

eth/main.cpp

@@ -136,6 +136,7 @@ void help()
 		<< "    -G,--opencl  When mining use the GPU via OpenCL." << endl
 		<< "    --opencl-platform <n>  When mining using -G/--opencl use OpenCL platform n (default: 0)." << endl
 		<< "    --opencl-device <n>  When mining using -G/--opencl use OpenCL device n (default: 0)." << endl
+		<< "    -t, --mining-threads <n> Limit number of CPU/GPU miners to n (default: use everything available on selected platform)" << endl
 		<< "Client networking:" << endl
 		<< "    --client-name <name>  Add a name to your client's version string (default: blank)." << endl
 		<< "    -b,--bootstrap  Connect to the default Ethereum peerserver." << endl
@@ -482,6 +483,7 @@ int main(int argc, char** argv)
 	MinerType minerType = MinerType::CPU;
 	unsigned openclPlatform = 0;
 	unsigned openclDevice	= 0;
+	unsigned miningThreads = UINT_MAX;
 
 	/// File name for import/export.
 	string filename;
@@ -850,6 +852,17 @@ int main(int argc, char** argv)
 					return -1;
 				}
 		}
+		else if ((arg == "-t" || arg == "--mining-threads") && i + 1 < argc)
+		{
+			try {
+				miningThreads = stol(argv[++i]);
+			}
+			catch (...)
+			{
+				cerr << "Bad " << arg << " option: " << argv[i] << endl;
+				return -1;
+			}
+		}
 		else if (arg == "-b" || arg == "--bootstrap")
 			bootstrap = true;
 		else if (arg == "-f" || arg == "--force-mining")
@@ -905,9 +918,16 @@ int main(int argc, char** argv)
 	if (sessionSecret)
 		sigKey = KeyPair(sessionSecret);
 
+	
+
+	if (minerType == MinerType::CPU) {
+		ProofOfWork::CPUMiner::setNumInstances(miningThreads);
+	}
+	else if (minerType == MinerType::GPU) {
 		ProofOfWork::GPUMiner::setDefaultPlatform(openclPlatform);
 		ProofOfWork::GPUMiner::setDefaultDevice(openclDevice);
-
+		ProofOfWork::GPUMiner::setNumInstances(miningThreads);
+	}
 	// Two codepaths is necessary since named block require database, but numbered
 	// blocks are superuseful to have when database is already open in another process.
 	if (mode == OperationMode::DAGInit && !(initDAG == LatestBlock || initDAG == PendingBlock))

libethash-cl/ethash_cl_miner.cpp

@@ -85,6 +85,27 @@ std::string ethash_cl_miner::platform_info(unsigned _platformId, unsigned _devic
 	return "{ \"platform\": \"" + platforms[platform_num].getInfo<CL_PLATFORM_NAME>() + "\", \"device\": \"" + device.getInfo<CL_DEVICE_NAME>() + "\", \"version\": \"" + device_version + "\" }";
 }
 
+unsigned ethash_cl_miner::get_num_devices(unsigned _platformId)
+{
+	std::vector<cl::Platform> platforms;
+	cl::Platform::get(&platforms);
+	if (platforms.empty())
+	{
+		debugf("No OpenCL platforms found.\n");
+		return 0;
+	}
+
+	std::vector<cl::Device> devices;
+	unsigned platform_num = std::min<unsigned>(_platformId, platforms.size() - 1);
+	platforms[platform_num].getDevices(CL_DEVICE_TYPE_ALL, &devices);
+	if (devices.empty())
+	{
+		debugf("No OpenCL devices found.\n");
+		return 0;
+	}
+	return devices.size();
+}
+
 void ethash_cl_miner::finish()
 {
 	if (m_queue())

libethash-cl/ethash_cl_miner.h

@@ -33,6 +33,8 @@ public:
 
 	bool init(ethash_params const& params, std::function<void(void*)> _fillDAG, unsigned workgroup_size = 64, unsigned _platformId = 0, unsigned _deviceId = 0);
 	static std::string platform_info(unsigned _platformId = 0, unsigned _deviceId = 0);
+	static unsigned get_num_devices(unsigned _platformId = 0);
+
 
 	void finish();
 	void hash(uint8_t* ret, uint8_t const* header, uint64_t nonce, unsigned count);

libethcore/Ethash.cpp

@@ -264,10 +264,12 @@ private:
 
 unsigned Ethash::GPUMiner::s_platformId = 0;
 unsigned Ethash::GPUMiner::s_deviceId = 0;
+unsigned Ethash::GPUMiner::s_numInstances = 1;
+unsigned Ethash::CPUMiner::s_numInstances = 1;
 
 Ethash::GPUMiner::GPUMiner(ConstructionInfo const& _ci):
 	Miner(_ci),
-	Worker("gpuminer"),
+	Worker("gpuminer" + toString(index())),
 	m_hook(new EthashCLHook(this))
 {
 }
@@ -308,6 +310,7 @@ void Ethash::GPUMiner::workLoop()
 
 			auto p = EthashAux::params(m_minerSeed);
 			auto cb = [&](void* d) { EthashAux::full(m_minerSeed, bytesRef((byte*)d, p.full_size)); };
+			unsigned device = instances() > 0 ? index() : s_deviceId;
 			m_miner->init(p, cb, 32, s_platformId, s_deviceId);
 		}
 
@@ -331,6 +334,11 @@ std::string Ethash::GPUMiner::platformInfo()
 	return ethash_cl_miner::platform_info(s_platformId, s_deviceId);
 }
 
+unsigned Ethash::GPUMiner::getNumDevices()
+{
+	return ethash_cl_miner::get_num_devices(s_platformId);
+}
+
 #endif
 
 }

libethcore/Ethash.h

@@ -79,16 +79,17 @@ public:
 	static WorkPackage package(BlockInfo const& _header);
 	static void assignResult(Solution const& _r, BlockInfo& _header) { _header.nonce = _r.nonce; _header.mixHash = _r.mixHash; }
 	
+
 	class CPUMiner: public Miner, Worker
 	{
 	public:
 		CPUMiner(ConstructionInfo const& _ci): Miner(_ci), Worker("miner" + toString(index())) {}
 
-		static unsigned instances() { return std::thread::hardware_concurrency(); }
+		static unsigned instances() { return s_numInstances > 0 ? s_numInstances : std::thread::hardware_concurrency(); }
 		static std::string platformInfo();
 		static void setDefaultPlatform(unsigned) {}
 		static void setDefaultDevice(unsigned) {}
-
+		static void setNumInstances(unsigned _instances) { s_numInstances = std::min<unsigned>(_instances, std::thread::hardware_concurrency()); }
 	protected:
 		void kickOff() override
 		{
@@ -100,7 +101,7 @@ public:
 
 	private:
 		void workLoop() override;
-		static unsigned s_deviceId;
+		static unsigned s_numInstances;
 	};
 
 #if ETH_ETHASHCL || !ETH_TRUE
@@ -112,10 +113,12 @@ public:
 		GPUMiner(ConstructionInfo const& _ci);
 		~GPUMiner();
 
-		static unsigned instances() { return 1; }
+		static unsigned instances() { return s_numInstances > 0 ? s_numInstances : 1; }
 		static std::string platformInfo();
+		static unsigned getNumDevices();
 		static void setDefaultPlatform(unsigned _id) { s_platformId = _id; }
 		static void setDefaultDevice(unsigned _id) { s_deviceId = _id; }
+		static void setNumInstances(unsigned _instances) { s_numInstances = std::min<unsigned>(_instances, getNumDevices()); }
 		
 	protected:
 		void kickOff() override;
@@ -133,6 +136,7 @@ public:
 		h256 m_minerSeed;		///< Last seed in m_miner
 		static unsigned s_platformId;
 		static unsigned s_deviceId;
+		static unsigned s_numInstances;
 	};
 #else
 	using GPUMiner = CPUMiner;