From owner-freebsd-questions@FreeBSD.ORG Wed Jan 5 23:46:53 2011 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id A5F461065672 for ; Wed, 5 Jan 2011 23:46:53 +0000 (UTC) (envelope-from Ggatten@waddell.com) Received: from mailhost0.waddell.com (mailhost0.waddell.com [12.154.38.61]) by mx1.freebsd.org (Postfix) with ESMTP id 626208FC12 for ; Wed, 5 Jan 2011 23:46:53 +0000 (UTC) Received: from mailhost3.waddell.com (mailhost3.waddell.com [10.1.10.28]) by mailhost0.waddell.com (Postfix) with ESMTP id F299B50980; Wed, 5 Jan 2011 17:46:47 -0600 (CST) Received: from mailhost3.waddell.com (localhost [127.0.0.1]) by localhost (Postfix) with SMTP id EB9343C336; Wed, 5 Jan 2011 17:46:47 -0600 (CST) Received: from WADPHTCAS0.waddell.com (wadphtcas0.waddell.com [192.168.203.229]) by mailhost3.waddell.com (Postfix) with ESMTP id D768B3C32D; Wed, 5 Jan 2011 17:46:47 -0600 (CST) Received: from WADPMBXV0.waddell.com ([169.254.1.151]) by WADPHTCAS0.waddell.com ([192.168.203.229]) with mapi; Wed, 5 Jan 2011 17:46:47 -0600 From: Gary Gatten To: 'Adam Vande More' Date: Wed, 5 Jan 2011 17:46:47 -0600 Thread-Topic: Swap Space - hijack? Thread-Index: AcutMbVhhYWloaCWQ3S9TtpPvLOSkAAAKEuw Message-ID: <27348_1294271207_4D2502E7_27348_6108_1_D9B37353831173459FDAA836D3B43499A7AF90D8@WADPMBXV0.waddell.com> References: <009b01cbad28$883d31c0$98b79540$@com> <19331_1294269649_4D24FCD1_19331_11348_1_D9B37353831173459FDAA836D3B43499A7AF90D4@WADPMBXV0.waddell.com> <20110105232403.000056a2@unknown> <27348_1294270392_4D24FFB8_27348_5874_1_D9B37353831173459FDAA836D3B43499A7AF90D6@WADPMBXV0.waddell.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: Bruce Cran , Jeff Whitman , "freebsd-questions@freebsd.org" Subject: RE: Swap Space - hijack? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Jan 2011 23:46:53 -0000 > Correct me if I'm wrong, but if necessary one could add (and > activate) a secondary / additional swap file if necessary without > rebooting. So maybe start with a few gig and add an additional swap > file if necessary? Swapping to a file is really slow and should only be done if absolutely necessary since every read/write has to go through the filesystem code which it doesn't do if done via a swap slice. Good point. It's been several years and back on v5 or 6 when I did somethi= ng like this. If there's unpartitioned space on the drive, can one add a s= econdary swap partition real-time? I forget what I did here - I'm sure I f= ollowed what's in the handbook re swap space. Probably did a swap file... Yes you can do that with swapon(1) It's been said though that FreeBSD memory paging algorithms take into accou= nt the system's entire available VM for deciding on when to act in low memo= ry conditions and these parameters are tuned expect some of that to be swap= space. That is why one reason there *should* be a least some swap space e= ven on a system w/ plenty of RAM. Sorry for the probable hijack... Speaking of swapping algorithms, is there = a way to force a parent and all child processes to NOT be swapped - period = - and always remain 100% in "real" memory? And if so, is it discouraged or= completely up to the sysadmin?
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