Re: Make MemoryContextMemAllocated() more precise - Mailing list pgsql-hackers

From Jeff Davis
Subject Re: Make MemoryContextMemAllocated() more precise
Date
Msg-id c04a9cb4b751a80c23fbd14ef1004d66f967c345.camel@j-davis.com
Whole thread Raw
In response to Re: Make MemoryContextMemAllocated() more precise  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: Make MemoryContextMemAllocated() more precise  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
On Thu, 2020-03-19 at 11:44 -0400, Robert Haas wrote:
> Procedurally, I think that it is highly inappropriate to submit a
> patch two weeks after the start of the final CommitFest and then
> commit it just over 48 hours later without a single endorsement of
> the
> change from anyone.

Reverted.

Sorry, I misjudged this as a "supporting fix for a specific problem",
but it seems others feel it requires discussion.

> Substantively, I think that whether or not this is improvement
> depends
> considerably on how your OS handles overcommit. I do not have enough
> knowledge to know whether it will be better in general, but would
> welcome opinions from others.

I think omitting the tail of the current block is an unqualified
improvement for the purpose of obeying work_mem, regardless of the OS.
The block sizes keep doubling up to 8MB, and it doesn't make a lot of
sense to count that last large mostly-empty block against work_mem.

Regards,
    Jeff Davis





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