atomic_gpu_memory.h
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Created: Sat, Nov 9, 14:08

atomic_gpu_memory.h
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	/* ----------------------------------------------------------------------
	LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
	http://lammps.sandia.gov, Sandia National Laboratories
	Steve Plimpton, sjplimp@sandia.gov

	Copyright (2003) Sandia Corporation. Under the terms of Contract
	DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
	certain rights in this software. This software is distributed under
	the GNU General Public License.

	See the README file in the top-level LAMMPS directory.
	------------------------------------------------------------------------- */

	/* ----------------------------------------------------------------------
	Contributing authors: Mike Brown (ORNL), brownw@ornl.gov
	------------------------------------------------------------------------- */

	#ifndef ATOMIC_GPU_MEMORY_H
	#define ATOMIC_GPU_MEMORY_H

	#include "pair_gpu_device.h"
	#include "pair_gpu_balance.h"
	#include "mpi.h"

	#ifdef USE_OPENCL
	#include "geryon/ocl_texture.h"
	#else
	#include "geryon/nvd_texture.h"
	#endif

	template <class numtyp, class acctyp>
	class AtomicGPUMemory {
	public:
	AtomicGPUMemory();
	virtual ~AtomicGPUMemory();

	/// Clear any previous data and set up for a new LAMMPS run
	/** \param max_nbors initial number of rows in the neighbor matrix
	* \param cell_size cutoff + skin
	* \param gpu_split fraction of particles handled by device
	*
	* Returns:
	* - 0 if successfull
	* - -1 if fix gpu not found
	* - -3 if there is an out of memory error
	* - -4 if the GPU library was not compiled for GPU
	* - -5 Double precision is not supported on card **/
	int init_atomic(const int nlocal, const int nall, const int max_nbors,
	const int maxspecial, const double cell_size,
	const double gpu_split, FILE *screen,
	const char *pair_program);

	/// Estimate the overhead for GPU context changes and CPU driver
	void estimate_gpu_overhead();

	/// Check if there is enough storage for atom arrays and realloc if not
	/ \param success set to false if insufficient memory /
	inline void resize_atom(const int inum, const int nall, bool &success) {
	if (atom->resize(nall, success))
	pos_tex.bind_float(atom->dev_x,4);
	ans->resize(inum,success);
	}

	/// Check if there is enough storage for neighbors and realloc if not
	/** \param nlocal number of particles whose nbors must be stored on device
	* \param host_inum number of particles whose nbors need to copied to host
	* \param current maximum number of neighbors
	* \note olist_size=total number of local particles **/
	inline void resize_local(const int inum, const int max_nbors, bool &success) {
	nbor->resize(inum,max_nbors,success);
	}

	/// Check if there is enough storage for neighbors and realloc if not
	/** \param nlocal number of particles whose nbors must be stored on device
	* \param host_inum number of particles whose nbors need to copied to host
	* \param current maximum number of neighbors
	* \note host_inum is 0 if the host is performing neighboring
	* \note nlocal+host_inum=total number local particles
	* \note olist_size=0 **/
	inline void resize_local(const int inum, const int host_inum,
	const int max_nbors, bool &success) {
	nbor->resize(inum,host_inum,max_nbors,success);
	}

	/// Clear all host and device data
	/ \note This is called at the beginning of the init() routine /
	void clear_atomic();

	/// Returns memory usage on device per atom
	int bytes_per_atom_atomic(const int max_nbors) const;

	/// Total host memory used by library for pair style
	double host_memory_usage_atomic() const;

	/// Accumulate timers
	inline void acc_timers() {
	if (device->time_device()) {
	if (nbor_time_avail) {
	nbor->time_nbor.add_to_total();
	nbor->time_kernel.add_to_total();
	nbor_time_avail=false;
	}
	time_pair.add_to_total();
	atom->acc_timers();
	ans->acc_timers();
	}
	}

	/// Zero timers
	inline void zero_timers() {
	nbor_time_avail=false;
	time_pair.zero();
	atom->zero_timers();
	ans->zero_timers();
	}

	/// Copy neighbor list from host
	int * reset_nbors(const int nall, const int inum, int ilist, int numj,
	int **firstneigh, bool &success);

	/// Build neighbor list on device
	void build_nbor_list(const int inum, const int host_inum,
	const int nall, double *host_x, int host_type,
	double sublo, double subhi, int tag, int *nspecial,
	int **special, bool &success);

	/// Pair loop with host neighboring
	void compute(const int f_ago, const int inum_full,
	const int nall, double *host_x, int host_type,
	int ilist, int numj, int **firstneigh, const bool eflag,
	const bool vflag, const bool eatom, const bool vatom,
	int &host_start, const double cpu_time, bool &success);

	/// Pair loop with device neighboring
	int * compute(const int ago, const int inum_full,
	const int nall, double *host_x, int host_type, double *sublo,
	double subhi, int tag, int **nspecial,
	int **special, const bool eflag, const bool vflag,
	const bool eatom, const bool vatom, int &host_start,
	const double cpu_time, bool &success);

	/// Pair loop with device neighboring
	int ** compute(const int ago, const int inum_full,
	const int nall, double *host_x, int host_type, double *sublo,
	double subhi, int tag, int **nspecial,
	int **special, const bool eflag, const bool vflag,
	const bool eatom, const bool vatom, int &host_start,
	int ilist, int numj, const double cpu_time, bool &success);

	// -------------------------- DEVICE DATA -------------------------

	/// Device Properties and Atom and Neighbor storage
	PairGPUDevice<numtyp,acctyp> *device;

	/// Geryon device
	UCL_Device *ucl_device;

	/// Device Timers
	UCL_Timer time_pair;

	/// Host device load balancer
	PairGPUBalance<numtyp,acctyp> hd_balancer;

	/// LAMMPS pointer for screen output
	FILE *screen;

	// --------------------------- ATOM DATA --------------------------

	/// Atom Data
	PairGPUAtom<numtyp,acctyp> *atom;

	// ------------------------ FORCE/ENERGY DATA -----------------------

	PairGPUAns<numtyp,acctyp> *ans;

	// --------------------------- NBOR DATA ----------------------------

	/// Neighbor data
	PairGPUNbor *nbor;

	/// True if we need to accumulate time for neighboring
	bool nbor_time_avail;

	// ------------------------- DEVICE KERNELS -------------------------
	UCL_Program *pair_program;
	UCL_Kernel k_pair_fast, k_pair;
	inline int block_size() { return _block_size; }

	// --------------------------- TEXTURES -----------------------------
	UCL_Texture pos_tex;

	protected:
	bool _compiled;
	int _block_size, _threads_per_atom;
	double _max_bytes, _max_an_bytes;
	double _gpu_overhead, _driver_overhead;
	UCL_D_Vec<int> *_nbor_data;

	void compile_kernels(UCL_Device &dev, const char *pair_string);

	virtual void loop(const bool _eflag, const bool _vflag) = 0;
	};

	#endif

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