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Commit ef7c7239 authored by Martin Bauer's avatar Martin Bauer
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Re-added compiled-in boundaries with tests 

are much faster in certain setups
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lbmpy/boundaries/boundaries_in_kernel.py 0 → 100644
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View file @ ef7c7239
import sympy as sp
from lbmpy.boundaries.boundaryhandling import BoundaryOffsetInfo, LbmWeightInfo
from pystencils.assignment import Assignment
from pystencils.astnodes import Block, Conditional, LoopOverCoordinate, SympyAssignment
from pystencils.data_types import type_all_numbers
from pystencils.field import Field
from pystencils.simp.assignment_collection import AssignmentCollection
from pystencils.simp.simplifications import sympy_cse_on_assignment_list
from pystencils.stencil import inverse_direction
from pystencils.sympyextensions import fast_subs
def direction_indices_in_direction(direction, stencil):
for i, offset in enumerate(stencil):
for d_i, o_i in zip(direction, offset):
if (d_i == 1 and o_i == 1) or (d_i == -1 and o_i == -1):
yield i
break
def boundary_substitutions(lb_method):
stencil = lb_method.stencil
w = lb_method.weights
replacements = {}
for idx, offset in enumerate(stencil):
symbolic_offset = BoundaryOffsetInfo.offset_from_dir(idx, dim=lb_method.dim)
for sym, value in zip(symbolic_offset, offset):
replacements[sym] = value
replacements[BoundaryOffsetInfo.inv_dir(idx)] = stencil.index(inverse_direction(offset))
replacements[LbmWeightInfo.weight_of_direction(idx)] = w[idx]
return replacements
def border_conditions(direction, field, ghost_layers=1):
abs_direction = tuple(-e if e < 0 else e for e in direction)
assert sum(abs_direction) == 1
idx = abs_direction.index(1)
val = direction[idx]
loop_ctrs = [LoopOverCoordinate.get_loop_counter_symbol(i) for i in range(len(direction))]
loop_ctr = loop_ctrs[idx]
gl = ghost_layers
border_condition = sp.Eq(loop_ctr, gl if val < 0 else field.shape[idx] - gl - 1)
if ghost_layers == 0:
return type_all_numbers(border_condition, loop_ctr.dtype)
else:
other_min = [sp.Ge(c, gl)
for c in loop_ctrs if c != loop_ctr]
other_max = [sp.Lt(c, field.shape[i] - gl)
for i, c in enumerate(loop_ctrs) if c != loop_ctr]
result = sp.And(border_condition, *other_min, *other_max)
return type_all_numbers(result, loop_ctr.dtype)
def transformed_boundary_rule(boundary, accessor_func, field, direction_symbol, lb_method, **kwargs):
tmp_field = field.new_field_with_different_name("t")
rule = boundary(tmp_field, direction_symbol, lb_method, **kwargs)
bsubs = boundary_substitutions(lb_method)
rule = [a.subs(bsubs) for a in rule]
accessor_writes = accessor_func(tmp_field, lb_method.stencil)
to_replace = set()
for assignment in rule:
to_replace.update({fa for fa in assignment.rhs.atoms(Field.Access) if fa.field == tmp_field})
def compute_replacement(fa):
f = fa.index[0]
shift = accessor_writes[f].offsets
new_index = tuple(a + b for a, b in zip(fa.offsets, shift))
return field[new_index](accessor_writes[f].index[0])
substitutions = {fa: compute_replacement(fa) for fa in to_replace}
all_assignments = [assignment.subs(substitutions) for assignment in rule]
main_assignments = [a for a in all_assignments if isinstance(a.lhs, Field.Access)]
sub_expressions = [a for a in all_assignments if not isinstance(a.lhs, Field.Access)]
assert len(main_assignments) == 1
ac = AssignmentCollection(main_assignments, sub_expressions).new_without_subexpressions()
return ac.main_assignments[0].rhs
def boundary_conditional(boundary, direction, read_of_next_accessor, lb_method, output_field, cse=False):
stencil = lb_method.stencil
tmp_field = output_field.new_field_with_different_name("t")
dir_indices = direction_indices_in_direction(direction, stencil)
assignments = []
for direction_idx in dir_indices:
rule = boundary(tmp_field, direction_idx, lb_method, index_field=None)
boundary_subs = boundary_substitutions(lb_method)
rule = [a.subs(boundary_subs) for a in rule]
rhs_substitutions = {tmp_field(i): sym for i, sym in enumerate(lb_method.post_collision_pdf_symbols)}
offset = stencil[direction_idx]
inv_offset = inverse_direction(offset)
inv_idx = stencil.index(inv_offset)
lhs_substitutions = {
tmp_field[offset](inv_idx): read_of_next_accessor(output_field, stencil)[inv_idx]}
rule = [Assignment(a.lhs.subs(lhs_substitutions), a.rhs.subs(rhs_substitutions)) for a in rule]
ac = AssignmentCollection([rule[-1]], rule[:-1]).new_without_subexpressions()
assignments += ac.main_assignments
border_cond = border_conditions(direction, output_field, ghost_layers=1)
if cse:
assignments = sympy_cse_on_assignment_list(assignments)
assignments = [SympyAssignment(a.lhs, a.rhs) for a in assignments]
return Conditional(border_cond, Block(assignments))
def update_rule_with_push_boundaries(collision_rule, field, boundary_spec, accessor, read_of_next_accessor):
method = collision_rule.method
loads = [Assignment(a, b) for a, b in zip(method.pre_collision_pdf_symbols, accessor.read(field, method.stencil))]
stores = [Assignment(a, b) for a, b in
zip(accessor.write(field, method.stencil), method.post_collision_pdf_symbols)]
result = collision_rule.copy()
result.subexpressions = loads + result.subexpressions
result.main_assignments += stores
for direction, boundary in boundary_spec.items():
cond = boundary_conditional(boundary, direction, read_of_next_accessor, method, field)
result.main_assignments.append(cond)
if 'split_groups' in result.simplification_hints:
substitutions = {b: a for a, b in zip(accessor.write(field, method.stencil), method.post_collision_pdf_symbols)}
new_split_groups = []
for split_group in result.simplification_hints['split_groups']:
new_split_groups.append([fast_subs(e, substitutions) for e in split_group])
result.simplification_hints['split_groups'] = new_split_groups
return result
lbmpy_tests/test_compiled_in_boundaries.ipynb 0 → 100644
+ 175
− 0
View file @ ef7c7239
%% Cell type:code id: tags:
``` python
from lbmpy.session import *
from lbmpy.boundaries.boundaries_in_kernel import update_rule_with_push_boundaries
from lbmpy.macroscopic_value_kernels import macroscopic_values_getter, macroscopic_values_setter
from collections import OrderedDict
from time import perf_counter
```
%% Cell type:markdown id: tags:
# Version 1: compile-in boundaries
%% Cell type:code id: tags:
``` python
domain_size = (32, 32, 32)
relaxation_rate = 1.8
time_steps = 100
lid_velocity = 0.05
```
%% Cell type:code id: tags:
``` python
dh = create_data_handling(domain_size, default_target='cpu')
pdfs = dh.add_array('pdfs', values_per_cell=19)
u = dh.add_array('u', values_per_cell=len(domain_size))
```
%% Cell type:code id: tags:
``` python
boundaries = OrderedDict((
((0, 1, 0), UBB([lid_velocity, 0, 0])),
((1, 0, 0), NoSlip()),
((-1, 0, 0), NoSlip()),
((0, -1, 0), NoSlip()),
((0, 0, 1), NoSlip()),
((0, 0, -1), NoSlip()),
))
opt = {'symbolic_field': pdfs, 'cse_global': False, 'cse_pdfs': True}
cr_even = create_lb_collision_rule(stencil="D3Q19", relaxation_rate=relaxation_rate, compressible=False, optimization=opt)
cr_odd = create_lb_collision_rule(stencil="D3Q19", relaxation_rate=relaxation_rate, compressible=False, optimization=opt)
update_rule_aa_even = update_rule_with_push_boundaries(cr_even, pdfs, boundaries, AAEvenTimeStepAccessor, AAOddTimeStepAccessor.read)
update_rule_aa_odd = update_rule_with_push_boundaries(cr_odd, pdfs, boundaries, AAOddTimeStepAccessor, AAEvenTimeStepAccessor.read)
getter_assignments = macroscopic_values_getter(update_rule_aa_even.method, velocity=u.center_vector,
pdfs=pdfs.center_vector, density=None)
getter_kernel = ps.create_kernel(getter_assignments, target=dh.default_target).compile()
even_kernel = ps.create_kernel(update_rule_aa_even, target=dh.default_target, ghost_layers=1).compile()
odd_kernel = ps.create_kernel(update_rule_aa_odd, target=dh.default_target, ghost_layers=1).compile()
```
%% Cell type:code id: tags:
``` python
def init():
dh.fill(pdfs.name, 0, ghost_layers=True)
def aa_time_loop(steps=100):
assert steps % 2 == 0, "Works only for an even number of time steps"
dh.all_to_gpu()
for i in range(steps // 2):
dh.run_kernel(odd_kernel)
dh.run_kernel(even_kernel)
dh.run_kernel(getter_kernel)
dh.all_to_cpu()
```
%% Cell type:code id: tags:
``` python
init()
aa_time_loop(time_steps)
vel_version1 = dh.gather_array(u.name, ghost_layers=False).copy()
plt.vector_field_magnitude(vel_version1[:, :, domain_size[2]//2, :])
plt.colorbar();
```
%% Output
%% Cell type:markdown id: tags:
# Version 2: Normal boundary handling
%% Cell type:code id: tags:
``` python
ldc = create_lid_driven_cavity(domain_size, relaxation_rate=relaxation_rate, lid_velocity=lid_velocity)
ldc.run(time_steps)
vel_version2 = ldc.velocity[:, :, :, :]
plt.vector_field_magnitude(vel_version2[:, :, domain_size[2]//2, :])
plt.colorbar();
```
%% Output
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