Why process memory starts so high up in virtual space with
yuri at rawbw.com
Mon Dec 1 14:57:29 PST 2008
Giorgos Keramidas wrote:
> The FreeBSD malloc(3) implementation can use either mmap() or sbrk() to
> obtain memory from the system. It does not 'waste a high percentage of
> memory' but it simply maps only high addresses (with an unmapped 'hole'
> in lower addresses).
But the hole it leaves with MALLOC_OPTIONS='dM' is way larger than the
one left by 'Dm' option. Usually malloc will keep allocating addresses
than this initial value and will never come back and fill some parts of
Therefore "wasting" this space.
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