From owner-freebsd-hackers@FreeBSD.ORG  Mon Mar 24 12:03:09 2014
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: hackers@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115])
 (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTPS id 78EC15A1
 for <hackers@freebsd.org>; Mon, 24 Mar 2014 12:03:09 +0000 (UTC)
Received: from mail-la0-x22d.google.com (mail-la0-x22d.google.com
 [IPv6:2a00:1450:4010:c03::22d])
 (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits))
 (No client certificate requested)
 by mx1.freebsd.org (Postfix) with ESMTPS id 00651AB8
 for <hackers@freebsd.org>; Mon, 24 Mar 2014 12:03:08 +0000 (UTC)
Received: by mail-la0-f45.google.com with SMTP id hr17so3516886lab.4
 for <hackers@freebsd.org>; Mon, 24 Mar 2014 05:03:07 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113;
 h=content-type:mime-version:subject:from:in-reply-to:date:cc
 :content-transfer-encoding:message-id:references:to;
 bh=/YlIW2HNy+XBP4ONqP3FVFD/Ec40H9bo5a7vxlgBCeY=;
 b=PAF7FF157fmksq9oXpSX+G2mH5DDRfUKuHzQ3rnn6ONBa6OcHmaPEXzl4LykuAmOkN
 L+RzNGphSGqMsZVZkBE2FFA3TZMnKGnvg/SgAU4cm24UJaoMLXLk8UBHceoDkN40w8n1
 3hcMolwKwZNNBm+86msLhkLXgS8cTX1z9hijHTNIeI9raqpspiDxeAlo29jQGaEhCoS4
 WsjkdDVofA/fus4ykQF9HIC9f+lx9aZR0t5ZicU9ClAqrgkdTFoa0WHnVrVZ3aHajGsI
 FlZmWJ9W2mzHGwuVeIt5Cu84O0vgTqtiVvBlFHm+stg9/zMmGQs3Q+9VifIFnS7HK50g
 lLug==
X-Received: by 10.112.171.1 with SMTP id aq1mr31198lbc.67.1395662587093;
 Mon, 24 Mar 2014 05:03:07 -0700 (PDT)
Received: from [10.0.1.20] ([176.193.80.226])
 by mx.google.com with ESMTPSA id jm3sm855523lbc.29.2014.03.24.05.03.05
 for <multiple recipients>
 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128);
 Mon, 24 Mar 2014 05:03:06 -0700 (PDT)
Content-Type: text/plain; charset=utf-8
Mime-Version: 1.0 (Mac OS X Mail 7.2 \(1874\))
Subject: Re: madvise() vs posix_fadvise()
From: Dmitry Sivachenko <trtrmitya@gmail.com>
In-Reply-To: <alpine.BSF.2.00.1403211725140.56113@mail.fig.ol.no>
Date: Mon, 24 Mar 2014 16:03:04 +0400
Content-Transfer-Encoding: quoted-printable
Message-Id: <C5489EF2-34D8-412C-88AC-476120D3F1F4@gmail.com>
References: <D6BD48AF-9522-495D-8D54-37854E53C272@gmail.com>
 <alpine.BSF.2.00.1403211725140.56113@mail.fig.ol.no>
To: =?utf-8?Q?Trond_Endrest=C3=B8l?= <Trond.Endrestol@fagskolen.gjovik.no>
X-Mailer: Apple Mail (2.1874)
Cc: hackers@freebsd.org
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
 <freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-hackers>, 
 <mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers/>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
 <mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 24 Mar 2014 12:03:09 -0000


On 21 =D0=BC=D0=B0=D1=80=D1=82=D0=B0 2014 =D0=B3., at 20:27, Trond =
Endrest=C3=B8l <Trond.Endrestol@fagskolen.gjovik.no> wrote:

> On Fri, 21 Mar 2014 18:56+0400, Dmitry Sivachenko wrote:
>=20
>> Hello!
>>=20
>> I have a program which uses large data files (read-only, via mmap()).
>>=20
>> These machines have a bit more RAM that these files occupy, so it is=20=

>> possible to have all these data in memory.
>>=20
>> What techniques should I use to promote this data not to be purged=20
>> from RAM:
>>=20
>> -- madvise(MADV_WILLNEED)
>> -- posix_fadvise(POSIX_FADV_WILLNEED)
>> -- both?
>=20
> Although a bit dangerous, mlock(2) might be your ticket. That system=20=

> call prevents your memory region from being swapped/paged away from=20
> physical memory.
>=20


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)?