Comment # 2 on bug 1201884 from Fabian Vogt

(In reply to Andreas Schwab from comment #1)
> MALLOC_PERTURB_ will always touch every newly allocated and every freed
> memory.  That's the whole point of it.

Yes, but I'm wondering whether it goes even further than that:

> FWICT, the bottleneck is that add_new_trans calls realloc very often, and glibc treats that like a new allocation + deallocation to be able to overwrite the old data. Maybe that can be optimized somehow?

i.e. does glibc effectively transform realloc into malloc + free or does it
realloc like before but just memset the additional space? Because according to
the perf report, pretty much all of the realloc cost is spent in _int_free,
while I'd expect that a noticable percentage of realloc calls could be expanded
in-place.