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[wip/exp] Simplify MPS availability check by removing platform dependency #21098

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[wip/exp] Simplify MPS availability check by removing platform dependency #21098

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ad1a70a
Fix: Simplify MPS availability check by removing platform dependency
bhimrazy Aug 19, 2025
b29bc5b
[pre-commit.ci] auto fixes from pre-commit.com hooks
pre-commit-ci[bot] Aug 19, 2025
ba72d39
Add macOS-13 to CI matrix for PyTorch testing
bhimrazy Aug 19, 2025
a9454a9
Add macOS-13 to CI matrix
bhimrazy Aug 20, 2025
94d84a2
# trigger pytorch test
bhimrazy Aug 20, 2025
9c8345a
[pre-commit.ci] auto fixes from pre-commit.com hooks
pre-commit-ci[bot] Aug 20, 2025
f6310f7
Apply suggestions from code review
Borda Aug 21, 2025
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2 changes: 2 additions & 0 deletions .github/workflows/ci-tests-fabric.yml
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Expand Up @@ -40,6 +40,8 @@ jobs:
matrix:
include:
# only run PyTorch latest
# macOS-13 is the latest version without Apple silicon
- { os: "macOS-13", pkg-name: "lightning", python-version: "3.10", pytorch-version: "2.1" }
- { os: "macOS-14", pkg-name: "lightning", python-version: "3.10", pytorch-version: "2.1" }
- { os: "ubuntu-22.04", pkg-name: "lightning", python-version: "3.10", pytorch-version: "2.1" }
- { os: "windows-2022", pkg-name: "lightning", python-version: "3.10", pytorch-version: "2.1" }
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3 changes: 2 additions & 1 deletion .github/workflows/ci-tests-pytorch.yml
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Expand Up @@ -43,7 +43,8 @@ jobs:
fail-fast: false
matrix:
include:
# only run PyTorch latest
# macOS-13 is the latest version without Apple silicon
- { os: "macOS-13", pkg-name: "lightning", python-version: "3.10", pytorch-version: "2.1" }
- { os: "macOS-14", pkg-name: "lightning", python-version: "3.10", pytorch-version: "2.1" }
- { os: "ubuntu-22.04", pkg-name: "lightning", python-version: "3.10", pytorch-version: "2.1" }
- { os: "windows-2022", pkg-name: "lightning", python-version: "3.10", pytorch-version: "2.1" }
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3 changes: 1 addition & 2 deletions src/lightning/fabric/accelerators/mps.py
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Expand Up @@ -12,7 +12,6 @@
# See the License for the specific language governing permissions and
# limitations under the License.
import os
import platform
from functools import lru_cache
from typing import Optional, Union

Expand Down Expand Up @@ -72,7 +71,7 @@ def auto_device_count() -> int:
def is_available() -> bool:
"""MPS is only available on a machine with the ARM-based Apple Silicon processors."""
mps_disabled = os.getenv("DISABLE_MPS", "0") == "1"
return not mps_disabled and torch.backends.mps.is_available() and platform.processor() in ("arm", "arm64")
return not mps_disabled and torch.backends.mps.is_available()
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what's the issue with the current checks?

We cannot easily remove them. MPS marks as available on older intel-based macs as well while not actually accelerating anything.

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that is why we add testing back with Intel to see what is happening and if we even have related tests to cover or refuse this change

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Even if it passes, it is slower than CPU on intel-macs and due to auto-selection users would end up with a non-optimal backend.


@classmethod
@override
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2 changes: 2 additions & 0 deletions tests/tests_pytorch/accelerators/test_mps.py
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Expand Up @@ -23,6 +23,8 @@
from lightning.pytorch.demos.boring_classes import BoringModel
from tests_pytorch.helpers.runif import RunIf

# trigger pytorch test


@RunIf(mps=True)
def test_get_mps_stats():
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