On Thu, Jan 16, 2020 at 01:41:39PM -0500, Tom Lane wrote:
Andres Freund <and...@anarazel.de> writes:
On 2020-01-16 18:01:53 +0100, Tomas Vondra wrote:
and it's only really used in debug builds anyway. So I'm not all that
woried about this wasting a couple extra kB of memory.
IDK, making memory usage look different makes optimizing it harder. Not
a hard rule, obviously, but ...
Well, if you're that excited about it, make a patch so we can see
how ugly it ends up being.
I think the question is how much memory would using globals actually
save, compared to including the bitmap in SlabContext.
The bitmap size depends on block/chunk size - I don't know what
parameters Andres uses for the additional contexts, but for the two
places already using Slab we have 8kB blocks with 80B and 240B chunks,
so ~102 and ~34 chunks in a block. So it's not a huge amount, and we
could easily reduce this to 1/8 by switching to a proper bitmap.
regards
--
Tomas Vondra http://www.2ndQuadrant.com
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