microsoft / microsoft/mimalloc

question about internal fragmentation limits

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Description

Hi Daan,

I've read in the README that in the worst case one can get 12.5% waste from the internal fragmentation.
However, when looking at the bin sizes https://github.com/microsoft/mimalloc/blob/v2.0.5/src/init.c#L56 I see they grow by 25%.
Say from 4096 to 5120. If I understand correctly it means that if one allocates 4097 bytes he would get a block of 5120 bytes.

Is documentation outdated or I am missing something?

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Research direction

Start with the README statement about 12.5% internal fragmentation and the bin-size definitions in src/init.c at line 56. Check how the allocator handles a request such as 4097 bytes and reconcile the apparent 25% growth; this is done when the README or its explanation accurately reflects the implementation.

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Assessment

Tech stack
c
Domain
documentation
Issue type
Documentation
Difficulty
2/5
Estimated time
1-3 hours
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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