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FiniteVolumeGPU/GPUSimulators/SHMEMSimulatorGroup.py
Martin Lilleeng Sætra 2da4640840 Added class for managing SHMEMSimulators
2021-05-05 15:24:34 +00:00

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Python
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# -*- coding: utf-8 -*-
"""
This python module implements SHMEM simulator group class
Copyright (C) 2020 Norwegian Meteorological Institute
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
import logging
from GPUSimulators import Simulator, CudaContext
import numpy as np
import pycuda.driver as cuda
class SHMEMGrid(object):
"""
Class which represents an SHMEM grid of GPUs. Facilitates easy communication between
neighboring subdomains in the grid. Contains one CUDA context per subdomain.
XXX: Adapted to debug on a single GPU. Either remove this possibility or
make it less hacky...
"""
def __init__(self, ngpus=None, ndims=2):
self.logger = logging.getLogger(__name__)
cuda.init(flags=0)
self.logger.info("Initializing CUDA")
num_cuda_devices = cuda.Device.count()
if ngpus is None:
#ngpus = num_cuda_devices
ngpus = 2
#assert ngpus <= num_cuda_devices, "Trying to allocate more GPUs than are available in the system."
assert ndims == 2, "Unsupported number of dimensions. Must be two at the moment"
#assert ngpus >= 2, "Must have at least two GPUs available to run multi-GPU simulations."
self.ngpus = ngpus
self.ndims = ndims
self.grid = SHMEMGrid.getGrid(self.ngpus, self.ndims)
self.logger.debug("Created {:}-dimensional SHMEM grid, using {:} GPUs".format(
self.ndims, self.ngpus))
# XXX: Is this a natural place to store the contexts? Consider moving contexts out of this class.
self.cuda_contexts = []
for i in range(self.ngpus):
#self.cuda_contexts.append(CudaContext.CudaContext(device=i, autotuning=False))
self.cuda_contexts.append(CudaContext.CudaContext(device=0, autotuning=False))
def getCoordinate(self, index):
i = (index % self.grid[0])
j = (index // self.grid[0])
return i, j
def getIndex(self, i, j):
return j*self.grid[0] + i
def getEast(self, index):
i, j = self.getCoordinate(index)
i = (i+1) % self.grid[0]
return self.getIndex(i, j)
def getWest(self, index):
i, j = self.getCoordinate(index)
i = (i+self.grid[0]-1) % self.grid[0]
return self.getIndex(i, j)
def getNorth(self, index):
i, j = self.getCoordinate(index)
j = (j+1) % self.grid[1]
return self.getIndex(i, j)
def getSouth(self, index):
i, j = self.getCoordinate(index)
j = (j+self.grid[1]-1) % self.grid[1]
return self.getIndex(i, j)
def getGrid(num_gpus, num_dims):
assert(isinstance(num_gpus, int))
assert(isinstance(num_dims, int))
# Adapted from https://stackoverflow.com/questions/28057307/factoring-a-number-into-roughly-equal-factors
# Original code by https://stackoverflow.com/users/3928385/ishamael
# Factorizes a number into n roughly equal factors
#Dictionary to remember already computed permutations
memo = {}
def dp(n, left): # returns tuple (cost, [factors])
"""
Recursively searches through all factorizations
"""
#Already tried: return existing result
if (n, left) in memo:
return memo[(n, left)]
#Spent all factors: return number itself
if left == 1:
return (n, [n])
#Find new factor
i = 2
best = n
bestTuple = [n]
while i * i < n:
#If factor found
if n % i == 0:
#Factorize remainder
rem = dp(n // i, left - 1)
#If new permutation better, save it
if rem[0] + i < best:
best = rem[0] + i
bestTuple = [i] + rem[1]
i += 1
#Store calculation
memo[(n, left)] = (best, bestTuple)
return memo[(n, left)]
grid = dp(num_gpus, num_dims)[1]
if (len(grid) < num_dims):
#Split problematic 4
if (4 in grid):
grid.remove(4)
grid.append(2)
grid.append(2)
#Pad with ones to guarantee num_dims
grid = grid + [1]*(num_dims - len(grid))
#Sort in descending order
grid = np.sort(grid)
grid = grid[::-1]
return grid
class SHMEMSimulatorGroup(Simulator.BaseSimulator):
"""
Class which handles communication and synchronization between simulators in different
contexts (presumably on different GPUs)
"""
def __init__(self, grid, **kwargs):
self.logger = logging.getLogger(__name__)
sims = []
for i in range(grid.ngpus):
local_sim = EE2D_KP07_dimsplit.EE2D_KP07_dimsplit(**kwargs)
sims[i] = SHMEMSimulator(i, local_sim, grid)
autotuner = sims[0].context.autotuner
sims[0].context.autotuner = None;
boundary_conditions = sims[0].getBoundaryConditions()
super().__init__(sims[0].context,
sims[0].nx, sims[0].ny,
sims[0].dx, sims[0].dy,
boundary_conditions,
sims[0].cfl_scale,
sims[0].num_substeps,
sims[0].block_size[0], sims[0].block_size[1])
sims[0].context.autotuner = autotuner
self.nsubdomains = grid.ngpus
self.sims = sims
self.grid = grid
#Get coordinate of this subdomain
#and handle global boundary conditions
new_boundary_conditions = Simulator.BoundaryCondition({
'north': Simulator.BoundaryCondition.Type.Dirichlet,
'south': Simulator.BoundaryCondition.Type.Dirichlet,
'east': Simulator.BoundaryCondition.Type.Dirichlet,
'west': Simulator.BoundaryCondition.Type.Dirichlet
})
gi, gj = grid.getCoordinate(self.index)
if (gi == 0 and boundary_conditions.west != Simulator.BoundaryCondition.Type.Periodic):
self.west = None
new_boundary_conditions.west = boundary_conditions.west;
if (gj == 0 and boundary_conditions.south != Simulator.BoundaryCondition.Type.Periodic):
self.south = None
new_boundary_conditions.south = boundary_conditions.south;
if (gi == grid.grid[0]-1 and boundary_conditions.east != Simulator.BoundaryCondition.Type.Periodic):
self.east = None
new_boundary_conditions.east = boundary_conditions.east;
if (gj == grid.grid[1]-1 and boundary_conditions.north != Simulator.BoundaryCondition.Type.Periodic):
self.north = None
new_boundary_conditions.north = boundary_conditions.north;
sim.setBoundaryConditions(new_boundary_conditions)
#Get number of variables
self.nvars = len(self.getOutput().gpu_variables)
#Shorthands for computing extents and sizes
gc_x = int(self.sim.getOutput()[0].x_halo)
gc_y = int(self.sim.getOutput()[0].y_halo)
nx = int(self.sim.nx)
ny = int(self.sim.ny)
self.logger.debug("Initialized {:d} subdomains".format(len(self.sims)))
# TODO: Re-implement methods below
def substep(self, dt, step_number):
self.exchange()
self.sim.substep(dt, step_number)
def getOutput(self):
return self.sim.getOutput()
def synchronize(self):
self.sim.synchronize()
def check(self):
return self.sim.check()
def computeDt(self):
local_dt = np.array([np.float32(self.sim.computeDt())])
global_dt = np.empty(1, dtype=np.float32)
self.grid.comm.Allreduce(local_dt, global_dt, op=MPI.MIN)
self.logger.debug("Local dt: {:f}, global dt: {:f}".format(local_dt[0], global_dt[0]))
return global_dt[0]
def getExtent(self):
"""
Function which returns the extent of the subdomain with index
index in the grid
"""
width = self.sim.nx*self.sim.dx
height = self.sim.ny*self.sim.dy
i, j = self.grid.getCoordinate(self.index)
x0 = i * width
y0 = j * height
x1 = x0 + width
y1 = y0 + height
return [x0, x1, y0, y1]
def exchange(self):
ns_download_before_exchange()
# GLOBAL SYNC
ns_do_exchange()
# GLOBAL SYNC
ns_upload_after_exchange()
ew_download_before_exchange()
# GLOBAL SYNC
ew_do_exchange()
# GLOBAL SYNC
ew_upload_after_exchange()
def ns_download_before_exchange(self):
####
# First transfer internal cells north-south
####
#Download from the GPU
if self.north is not None:
for k in range(self.nvars):
self.sim.u0[k].download(self.sim.stream, cpu_data=self.out_n[k,:,:], asynch=True, extent=self.read_n)
if self.south is not None:
for k in range(self.nvars):
self.sim.u0[k].download(self.sim.stream, cpu_data=self.out_s[k,:,:], asynch=True, extent=self.read_s)
self.sim.stream.synchronize()
def ns_do_exchange(self):
#Send/receive to north/south neighbours
comm_send = []
comm_recv = []
if self.north is not None:
comm_send += [self.grid.comm.Isend(self.out_n, dest=self.north, tag=4*self.nt + 0)]
comm_recv += [self.grid.comm.Irecv(self.in_n, source=self.north, tag=4*self.nt + 1)]
if self.south is not None:
comm_send += [self.grid.comm.Isend(self.out_s, dest=self.south, tag=4*self.nt + 1)]
comm_recv += [self.grid.comm.Irecv(self.in_s, source=self.south, tag=4*self.nt + 0)]
#Wait for incoming transfers to complete
for comm in comm_recv:
comm.wait()
def ns_upload_after_exchange(self):
#Upload to the GPU
if self.north is not None:
for k in range(self.nvars):
self.sim.u0[k].upload(self.sim.stream, self.in_n[k,:,:], extent=self.write_n)
if self.south is not None:
for k in range(self.nvars):
self.sim.u0[k].upload(self.sim.stream, self.in_s[k,:,:], extent=self.write_s)
#Wait for sending to complete
for comm in comm_send:
comm.wait()
def ew_download_before_exchange(self):
####
# Then transfer east-west including ghost cells that have been filled in by north-south transfer above
####
#Download from the GPU
if self.east is not None:
for k in range(self.nvars):
self.sim.u0[k].download(self.sim.stream, cpu_data=self.out_e[k,:,:], asynch=True, extent=self.read_e)
if self.west is not None:
for k in range(self.nvars):
self.sim.u0[k].download(self.sim.stream, cpu_data=self.out_w[k,:,:], asynch=True, extent=self.read_w)
self.sim.stream.synchronize()
def ew_do_exchange(self):
#Send/receive to east/west neighbours
comm_send = []
comm_recv = []
if self.east is not None:
comm_send += [self.grid.comm.Isend(self.out_e, dest=self.east, tag=4*self.nt + 2)]
comm_recv += [self.grid.comm.Irecv(self.in_e, source=self.east, tag=4*self.nt + 3)]
if self.west is not None:
comm_send += [self.grid.comm.Isend(self.out_w, dest=self.west, tag=4*self.nt + 3)]
comm_recv += [self.grid.comm.Irecv(self.in_w, source=self.west, tag=4*self.nt + 2)]
#Wait for incoming transfers to complete
for comm in comm_recv:
comm.wait()
def ew_upload_after_exchange(self):
#Upload to the GPU
if self.east is not None:
for k in range(self.nvars):
self.sim.u0[k].upload(self.sim.stream, self.in_e[k,:,:], extent=self.write_e)
if self.west is not None:
for k in range(self.nvars):
self.sim.u0[k].upload(self.sim.stream, self.in_w[k,:,:], extent=self.write_w)
#Wait for sending to complete
for comm in comm_send:
comm.wait()
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