From 86a6112e8fe8745eaa6f71c6a185cd64e8ec2bb5 Mon Sep 17 00:00:00 2001
From: Markus Holzer <markus.holzer@fau.de>
Date: Sun, 2 Jun 2024 17:15:15 +0200
Subject: [PATCH] Fuse thread safety check with existing check
---
src/pystencils/config.py | 11 +++--------
src/pystencils/kernel_contrains_check.py | 5 +++--
src/pystencils/kernelcreation.py | 6 ------
3 files changed, 6 insertions(+), 16 deletions(-)
diff --git a/src/pystencils/config.py b/src/pystencils/config.py
index fafc34178..dec9df8ba 100644
--- a/src/pystencils/config.py
+++ b/src/pystencils/config.py
@@ -135,14 +135,9 @@ class CreateKernelConfig:
"""
skip_independence_check: bool = False
"""
- Don't check that loop iterations are independent. This is needed e.g. for
- periodicity kernel, that access the field outside the iteration bounds. Use with care!
- """
- check_thread_safety: bool = True
- """
- Assignments are considered thread safe if read and writes only target the same locations. If this is not the case,
- multithreaded optimisations will fail. The thread safety check can be deactivated to use e.g. GPUs anyway.
- Use with care!
+ By default the assignment list is checked for read/write independence. This means fields are only written at
+ locations where they are read. Doing so guarantees thread safety. In some cases e.g. for
+ periodicity kernel, this can not be assured and does the check needs to be deactivated. Use with care!
"""
class DataTypeFactory:
diff --git a/src/pystencils/kernel_contrains_check.py b/src/pystencils/kernel_contrains_check.py
index b72e084a3..f33434a0e 100644
--- a/src/pystencils/kernel_contrains_check.py
+++ b/src/pystencils/kernel_contrains_check.py
@@ -43,7 +43,6 @@ class KernelConstraintsCheck:
self.fields_read = set()
self.check_independence_condition = check_independence_condition
self.check_double_write_condition = check_double_write_condition
- self.thread_safe = True
def visit(self, obj):
if isinstance(obj, (AssignmentCollection, NodeCollection)):
@@ -117,7 +116,9 @@ class KernelConstraintsCheck:
if fai in self.field_reads:
reads = tuple(self.field_reads[fai])
if len(reads) > 1 or lhs.offsets != reads[0]:
- self.thread_safe = False
+ if self.check_independence_condition:
+ raise ValueError(f"Field {lhs.field.name} is written at different location than it was read. "
+ f"This means the resulting kernel would not be thread safe")
elif isinstance(lhs, sp.Symbol):
if self.scopes.is_defined_locally(lhs):
raise ValueError(f"Assignments not in SSA form, multiple assignments to {lhs.name}")
diff --git a/src/pystencils/kernelcreation.py b/src/pystencils/kernelcreation.py
index 8dd7b90fc..59986e8d8 100644
--- a/src/pystencils/kernelcreation.py
+++ b/src/pystencils/kernelcreation.py
@@ -130,12 +130,6 @@ def create_domain_kernel(assignments: NodeCollection, *, config: CreateKernelCon
check_double_write_condition=not config.allow_double_writes)
check.visit(assignments)
- if not check.thread_safe and config.check_thread_safety:
- base = "Assignments are not thread safe because data is read and written on different locations."
- if config.cpu_openmp:
- raise ValueError(f"{base} OpenMP optimisation is not permitted in this scenario.")
- if config.target == Target.GPU:
- raise ValueError(f"{base} GPU target is not permitted in this case, only CPU target with single thread")
assignments.bound_fields = check.fields_written
assignments.rhs_fields = check.fields_read
--
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