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Subject: Re: Behavior of madvise(MADV_FREE)
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From: Jason Evans <jasone@freebsd.org>
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Date: Fri, 12 Oct 2012 15:05:22 -0700
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To: Marcel Moolenaar <marcel@xcllnt.net>
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On Oct 12, 2012, at 1:54 PM, Marcel Moolenaar wrote:
> BTW: MADV_DONTNEED in Linux seems to behave like MADV_FREE
> in FreeBSD -- at least according to the manpage. Which makes
> me wonder how standard madvise(2) is anyway.

MADV_DONTNEED on Linux immediately dissociates the physical page from =
the VM mapping, such that subsequent access results in a zero-filled =
page being soft-faulted into place.

MADV_FREE is *way* nicer than MADV_DONTNEED in the context of malloc.  =
jemalloc has a really discouraging amount of complexity that is directly =
a result of working around the performance overhead of MADV_DONTNEED.

Jason=