Date: Fri, 12 Oct 2012 15:05:22 -0700 From: Jason Evans <jasone@freebsd.org> To: Marcel Moolenaar <marcel@xcllnt.net> Cc: Poul-Henning Kamp <phk@phk.freebsd.dk>, "freebsd-arch@freebsd.org Arch" <freebsd-arch@freebsd.org>, Tim LaBerge <tlaberge@juniper.net>, Alan Cox <alc@rice.edu> Subject: Re: Behavior of madvise(MADV_FREE) Message-ID: <F71ACE9D-297E-4565-BB8D-D95D46D90708@freebsd.org> In-Reply-To: <E6A52D27-0D6A-4175-9ECA-ADE25BFF35C2@xcllnt.net> References: <9FEBC10C-C453-41BE-8829-34E830585E90@xcllnt.net> <4835.1350062021@critter.freebsd.dk> <E6A52D27-0D6A-4175-9ECA-ADE25BFF35C2@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=
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