Date: Mon, 24 Mar 2014 16:03:04 +0400 From: Dmitry Sivachenko <trtrmitya@gmail.com> To: =?utf-8?Q?Trond_Endrest=C3=B8l?= <Trond.Endrestol@fagskolen.gjovik.no> Cc: hackers@freebsd.org Subject: Re: madvise() vs posix_fadvise() Message-ID: <C5489EF2-34D8-412C-88AC-476120D3F1F4@gmail.com> In-Reply-To: <alpine.BSF.2.00.1403211725140.56113@mail.fig.ol.no> References: <D6BD48AF-9522-495D-8D54-37854E53C272@gmail.com> <alpine.BSF.2.00.1403211725140.56113@mail.fig.ol.no>
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On 21 марта 2014 г., at 20:27, Trond Endrestøl <Trond.Endrestol@fagskolen.gjovik.no> wrote: > On Fri, 21 Mar 2014 18:56+0400, Dmitry Sivachenko wrote: > >> Hello! >> >> I have a program which uses large data files (read-only, via mmap()). >> >> These machines have a bit more RAM that these files occupy, so it is >> possible to have all these data in memory. >> >> What techniques should I use to promote this data not to be purged >> from RAM: >> >> -- madvise(MADV_WILLNEED) >> -- posix_fadvise(POSIX_FADV_WILLNEED) >> -- both? > > Although a bit dangerous, mlock(2) might be your ticket. That system > call prevents your memory region from being swapped/paged away from > physical memory. > I know about mlock(2), it is a bit overkill. Can someone please explain the difference between madvise(MADV_WILLNEED) and posix_fadvise(POSIX_FADV_WILLNEED)?
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