lmdb: Platform-specific default map size #111
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The current code works fine on x86 platforms since x86-64 uses at least
48-bit of virtual address space. On other 64-bit platforms like aarch64
or riscv64, the minimum allowed virtual address is 39-bit [1] [2].
Current 2**40 allocation will fail:
```
zict/tests/test_lmdb.py:53:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
self = <zict.lmdb.LMDB object at 0x40043bfc10>
directory = '/tmp/test_lmdb-sfepfnw8'
def __init__(self, directory: str):
import lmdb
# map_size is the maximum database size but shouldn't fill up the
# virtual address space
map_size = 1 << 40 if sys.maxsize >= 2**32 else 1 << 28
# writemap requires sparse file support otherwise the whole
# `map_size` may be reserved up front on disk
writemap = sys.platform.startswith("linux")
> self.db = lmdb.open(
directory,
subdir=True,
map_size=map_size,
sync=False,
writemap=writemap,
)
E lmdb.Error: /tmp/test_lmdb-sfepfnw8: Operation not supported
zict/lmdb.py:43: Error
```
Switching to 2**37 on aarch64 and riscv64 should fix the issue.
[1]: https://www.kernel.org/doc/html/v5.8/arm64/memory.html
[2]: https://www.kernel.org/doc/html/latest/riscv/vm-layout.html
hack3ric
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Oct 31, 2023
Backported map size fix from dask/zict#111.
jrbourbeau
reviewed
Oct 31, 2023
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cc @crusaderky if you have bandwidth to take a look at this
felixonmars
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Backported map size fix from dask/zict#111.
crusaderky
requested changes
Nov 7, 2023
Comment on lines
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| elif machine in ["x86_64", "x64"]: | ||
| map_size = 2**40 | ||
| elif machine in ["i386", "i686", "x86"]: | ||
| map_size = 2**30 |
There was a problem hiding this comment.
Suggested change
| elif machine in ["x86_64", "x64"]: | |
| map_size = 2**40 | |
| elif machine in ["i386", "i686", "x86"]: | |
| map_size = 2**30 |
Wasn't this already covered by sys.maxsize // 4?
| map_size = 2**40 | ||
| elif machine in ["i386", "i686", "x86"]: | ||
| map_size = 2**30 | ||
| elif machine.startswith("aarch64") or machine.startswith("armv8") or machine.startswith("riscv64"): |
There was a problem hiding this comment.
Suggested change
| elif machine.startswith("aarch64") or machine.startswith("armv8") or machine.startswith("riscv64"): | |
| elif ( | |
| machine.startswith("aarch64") | |
| or machine.startswith("armv8") | |
| or machine.startswith("riscv64") | |
| ): | |
| # x86-64 uses at least 48-bit of virtual address space. On other 64-bit platforms like aarch64 | |
| # or riscv64, the minimum allowed virtual address is 39-bit so 2**40 allocation will fail. |
crusaderky
reviewed
Nov 7, 2023
| map_size = 2**40 | ||
| elif machine in ["i386", "i686", "x86"]: | ||
| map_size = 2**30 | ||
| elif machine.startswith("aarch64") or machine.startswith("armv8") or machine.startswith("riscv64"): |
There was a problem hiding this comment.
What about 32-bit armv8?
aimixsaka
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Apr 29, 2024
- Temporarily vendor fix-map-size.patch to fix rotten - Waiting for dask/zict#111
felixonmars
pushed a commit
to felixonmars/archriscv-packages
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May 6, 2024
- Temporarily vendor fix-map-size.patch to fix rotten - Waiting for dask/zict#111
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The current code works fine on x86 platforms since x86-64 uses at least 48-bit of virtual address space. On other 64-bit platforms like aarch64 or riscv64, the minimum allowed virtual address is 39-bit 1 2. Current 2**40 allocation will fail:
Switching to 2**37 on aarch64 and riscv64 should fix the issue.