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Date:      Thu, 22 Dec 2011 11:22:47 +0100 (CET)
From:      "Ganael LAPLANCHE" <ganael.laplanche@martymac.org>
To:        Artem Belevich <art@freebsd.org>, Tijl Coosemans <tijl@coosemans.org>
Cc:        freebsd-stable@freebsd.org
Subject:   Re: Using mmap(2) with a hint address
Message-ID:  <20111222101830.M52727@martymac.org>
In-Reply-To: <CAFqOu6h=kuh2HrVo01mS6u8N1R-q3Sjxjj6cbk2jFiXnzSSgKw@mail.gmail.com>
References:  <20111220080437.M63044@martymac.org> <4EF05F27.8030902@FreeBSD.org> <20111220134716.M62917@martymac.org> <20111220142740.M29405@martymac.org> <4EF0A3A7.80309@FreeBSD.org> <CAFqOu6h=kuh2HrVo01mS6u8N1R-q3Sjxjj6cbk2jFiXnzSSgKw@mail.gmail.com>

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Hi Artem, Tijl,

On Tue, 20 Dec 2011 09:27:43 -0800, Artem Belevich wrote
> Something like that. [...]
> These days malloc() by default uses mmap, so if you don't force it to
> use sbrk() you can probably lower MAXDSIZE and let kernel use most
> of address space for hinted mmaps.
> [...]

On Tue, 20 Dec 2011 18:45:08 +0100, Tijl Coosemans wrote
> I don't know about NetBSD but Linux maps from the stack 
> downwards when there's no hint and FreeBSD maps from the 
> program upwards. [...]
> malloc(3) used to be implemented on top of brk(2) so the size was
> increased on amd64 so you could malloc more memory. Nowadays malloc
> can use mmap(2) so a large datasize isn't really needed anymore.

I will use setrlimit(2) to lower datasize then.

Thanks a lot for your time and explanations,
Best regards,

--
Ganael LAPLANCHE <ganael.laplanche@martymac.org>
http://www.martymac.org | http://contribs.martymac.org
FreeBSD: martymac <martymac@FreeBSD.org>, http://www.FreeBSD.org



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