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From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no>
To: Peter Schuller <peter.schuller@infidyne.com>
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Date: Thu, 10 Jan 2008 15:31:32 +0100
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Cc: Andrew Reilly <andrew-freebsd@areilly.bpc-users.org>,
	Peter Jeremy <peterjeremy@optushome.com.au>,
	Poul-Henning Kamp <phk@phk.freebsd.dk>, freebsd-current@freebsd.org,
	Igor Mozolevsky <igor@hybrid-lab.co.uk>,
	Kostik Belousov <kostikbel@gmail.com>
Subject: Re: sbrk(2) broken
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Dag-Erling Sm=C3=B8rgrav <des@des.no> writes:
> Peter Schuller <peter.schuller@infidyne.com> writes:
> > However, in this context it will likely only help partially since you s=
till
> > need a full page to be free (and with a lot of programs many allocation=
s will
> > be significantly smaller than that, and I have to assume no real-life m=
alloc
> > 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.

I misread your "no" as "any", so it seems we are in violent agreement.

However, most allocators these days are zone or slab allocators (or
similar in principle), and are pretty good at minimizing external
fragmentation except for pathological cases, which are suprisingly rare
in practice.

DES
--=20
Dag-Erling Sm=C3=B8rgrav - des@des.no