Atsushi Ogawa <atsushi.ogawa@gmail.com> writes:
> (1)accounts table (4 columns, 1,000,000 tuples)
> malloc calls allocated(bytes) unused(bytes) execution time
> --------------------------------------------------------------------------
> 8.1.0 80,542 164,950,016 2,946,402 6.80 sec.
> patched 86 161,478,656 177,650 6.73 sec.
This hardly seems credible --- your patch would result in more wasted
memory, not less. It looks to me like the instrumentation you added
assumes that extra space in a malloc block will never be used later,
which of course is not true ...
regards, tom lane