Re: Reducing the chunk header sizes on all memory context types

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От Andres Freund
Тема Re: Reducing the chunk header sizes on all memory context types
Дата
Msg-id 20220712174404.polbc5it7j6mzmql@awork3.anarazel.de
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Ответ на Re: Reducing the chunk header sizes on all memory context types  (Yura Sokolov <y.sokolov@postgrespro.ru>)
Ответы Re: Reducing the chunk header sizes on all memory context types  (David Rowley <dgrowleyml@gmail.com>)
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Hi,

On 2022-07-12 20:22:57 +0300, Yura Sokolov wrote:
> I don't get, why "large chunk" needs additional fields for size and
> offset.
> Large allocation sizes are certainly rounded to page size.
> And allocations which doesn't fit 1GB we could easily round to 1MB.
> Then we could simply store `size>>20`.
> It will limit MaxAllocHugeSize to `(1<<(30+20))-1` - 1PB. Doubdfully we
> will deal with such huge allocations in near future.

What would gain by doing something like this? The storage density loss of
storing an exact size is smaller than what you propose here.

Greetings,

Andres Freund



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