gh-112532: Improve mimalloc page visiting #114133
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This adds support for visiting abandoned pages in mimalloc and improves the performance of the page visiting code. Abandoned pages contain memory blocks from threads that have exited. At some point, they may be later reclaimed by other threads. We still need to visit those pages in the free-threaded GC because they contain live objects. This also reduces the overhead of visiting mimalloc pages: * Special cases for full, empty, and pages containing only a single block. * Fix free_map to use one bit instead of one byte per block. * Use fast integer division by a constant algorithm when computing block offset from block size and index.
DinoV
reviewed
Jan 17, 2024
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| // Visit all blocks in a abandoned segments | ||
| bool _mi_abandoned_pool_visit_blocks(mi_abandoned_pool_t* pool, uint8_t page_tag, bool visit_blocks, mi_block_visit_fun* visitor, void* arg) { |
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This (and therefore the previous 2 functions) doesn't seem to be used anywhere?
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These will be used in the upcoming GC PR. Here is an example usage:
I put them in this PR because:
- Keeping the mimalloc changes separate makes them a bit easier to track and upstream
- The GC PR will be big and doing this first makes the upcoming PR a bit smaller
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@DinoV, would you please merge this when you are ready? |
aisk
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This adds support for visiting abandoned pages in mimalloc and improves the performance of the page visiting code. Abandoned pages contain memory blocks from threads that have exited. At some point, they may be later reclaimed by other threads. We still need to visit those pages in the free-threaded GC because they contain live objects. This also reduces the overhead of visiting mimalloc pages: * Special cases for full, empty, and pages containing only a single block. * Fix free_map to use one bit instead of one byte per block. * Use fast integer division by a constant algorithm when computing block offset from block size and index.
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daanx
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daanx
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This adds support for visiting abandoned pages in mimalloc and improves the performance of the page visiting code. Abandoned pages contain memory blocks from threads that have exited. At some point, they may be later reclaimed by other threads. We still need to visit those pages in the free-threaded GC because they contain live objects. This also reduces the overhead of visiting mimalloc pages: * Special cases for full, empty, and pages containing only a single block. * Fix free_map to use one bit instead of one byte per block. * Use fast integer division by a constant algorithm when computing block offset from block size and index.
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This adds support for visiting abandoned pages in mimalloc and improves the performance of the page visiting code. Abandoned pages contain memory blocks from threads that have exited. At some point, they may be later reclaimed by other threads. We still need to visit those pages in the free-threaded GC because they contain live objects.
This also reduces the overhead of visiting mimalloc pages: