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VILLASnode/include/villas/nodes/fpga.hpp
Niklas Eiling a2b7050fd1 fpga: improve dma latency
Signed-off-by: Niklas Eiling <niklas.eiling@eonerc.rwth-aachen.de>
2024-04-18 10:35:11 +02:00

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3.4 KiB
C++

/* Communicate with VILLASfpga Xilinx FPGA boards.
*
* Author: Steffen Vogel <post@steffenvogel.de>
* Author: Niklas Eiling <niklas.eiling@eonerc.rwth-aachen.de>
* SPDX-FileCopyrightText: 2014-2023 Institute for Automation of Complex Power Systems, RWTH Aachen University
* SPDX-FileCopyrightText: 2023 Niklas Eiling <niklas.eiling@eonerc.rwth-aachen.de>
* SPDX-License-Identifier: Apache-2.0
*/
#pragma once
#include <thread>
#include <villas/format.hpp>
#include <villas/node.hpp>
#include <villas/node/config.hpp>
#include <villas/timing.hpp>
#include <villas/fpga/card.hpp>
#include <villas/fpga/ips/dma.hpp>
#include <villas/fpga/node.hpp>
#include <villas/fpga/pcie_card.hpp>
namespace villas {
namespace node {
class FpgaNode : public Node {
enum InterfaceType { PCIE, PLATFORM };
protected:
// Settings
std::string cardName;
std::list<std::string> connectStrings;
// This setting decouples DMA management from Data processing.
// With this setting set to true, the DMA management for both read and
// write transactions is performed after the write command has been send
// the DMA controller.
// This allows us to achieve very low latencies for an application that
// waits for data from the FPGA processes it, and finished a time step
// by issuing a write to the FPGA.
bool lowLatencyMode;
// This setting performs synchronization with DMA controller in separate
// threads. It requires lowLatencyMode to be set to true.
// This may improve latency, because DMA management is completely decoupled
// from the data path, or may increase latency because of additional thread
// synchronization overhead. Only use after verifying that it improves latency.
bool asyncDmaManagement;
// State
std::shared_ptr<fpga::Card> card;
std::shared_ptr<villas::fpga::ip::Dma> dma;
std::shared_ptr<villas::MemoryBlock> blockRx;
std::shared_ptr<villas::MemoryBlock> blockTx;
// Non-public methods
virtual int asyncRead(Sample *smps[], unsigned cnt);
virtual int slowRead(Sample *smps[], unsigned cnt);
virtual int _read(Sample *smps[], unsigned cnt) override;
virtual int _write(Sample *smps[], unsigned cnt) override;
// only used if asyncDmaManagement is true
volatile std::atomic_bool readActive;
volatile std::atomic_bool writeActive;
volatile std::atomic_bool stopThreads;
std::shared_ptr<std::thread> dmaThread;
virtual int dmaMgmtThread();
public:
FpgaNode(const uuid_t &id = {}, const std::string &name = "");
virtual ~FpgaNode();
virtual int prepare() override;
virtual int parse(json_t *json) override;
virtual int check() override;
virtual int start() override;
virtual int stop() override;
virtual std::vector<int> getPollFDs() override;
virtual const std::string &getDetails() override;
};
class FpgaNodeFactory : public NodeFactory {
public:
using NodeFactory::NodeFactory;
virtual Node *make(const uuid_t &id = {},
const std::string &nme = "") override {
auto *n = new FpgaNode(id, nme);
init(n);
return n;
}
virtual int getFlags() const override {
return (int)NodeFactory::Flags::SUPPORTS_READ |
(int)NodeFactory::Flags::SUPPORTS_WRITE |
(int)NodeFactory::Flags::SUPPORTS_POLL;
}
virtual std::string getName() const override { return "fpga"; }
virtual std::string getDescription() const override { return "VILLASfpga"; }
virtual int start(SuperNode *sn) override;
};
} // namespace node
} // namespace villas