sbrk(2) broken

Dag-Erling Smørgrav des at
Thu Jan 10 02:04:13 PST 2008

Peter Schuller <peter.schuller at> writes:
> Dag-Erling Smørgrav <des at> writes:
> > Actually, malloc(3) can use madvise(2) to notify the kernel that
> > arbitrary pages in the arena are unused and can be discarded.  The
> > current implementation will do so if the H option is specified.
> However, in this context it will likely only help partially since you still
> need a full page to be free (and with a lot of programs many allocations will
> be significantly smaller than that, and I have to assume no real-life malloc
> will align all allocations to pages, or the overhead would be extreme).

Page-aligning every allocation would be supremely stupid, and jemalloc
does so only for allocations larger than a page.

Dag-Erling Smørgrav - des at

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