On 8/8/21 12:11 PM, David Rowley wrote:
On Sat, 7 Aug 2021 at 12:10, Tomas Vondra <tomas.von...@enterprisedb.com> wrote:
All of the tests show that the patches to improve the allocation
efficiency of generation.c don't help to improve the results of the
test cases. I wondered if it's maybe worth trying to see what happens
if instead of doubling the allocations each time, quadruple them
instead. I didn't try this.
I doubt quadrupling the allocations won't help very much, but I suspect
the problem might be in the 0004 patch - at least that's what shows
regression in my results. Could you try with just 0001-0003 applied?
I tried the quadrupling of the buffer instead of doubling it each time
and got the attached. Column E, or green in the graphs show the
results of that. It's now much closer to the original patch which just
made the block size 8MB.
Interesting, I wouldn't have expected that to make such difference.
I'm not sure quadrupling the size is a good idea, though, because it
increases the amount of memory we might be wasting. With the doubling,
the amount of wasted /unused memory is limited to ~50%, because the next
block is (roughly) equal to sum of already allocated blocks, so
allocating just 1B on it leaves us with 50%. But quadrupling the size
means we'll end up with ~75% free space. Of course, this is capped by
the maximum block size etc. but still ...
regards
--
Tomas Vondra
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