From owner-freebsd-questions@freebsd.org Tue Dec 12 01:28:16 2017 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id D1388E8380E for ; Tue, 12 Dec 2017 01:28:16 +0000 (UTC) (envelope-from freebsd@dreamchaser.org) Received: from nightmare.dreamchaser.org (ns.dreamchaser.org [66.109.141.57]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 83A0336C0; Tue, 12 Dec 2017 01:28:16 +0000 (UTC) (envelope-from freebsd@dreamchaser.org) Received: from breakaway.dreamchaser.org (breakaway [192.168.151.122]) by nightmare.dreamchaser.org (8.15.2/8.15.2) with ESMTP id vBC1S7V1014366; Mon, 11 Dec 2017 18:28:08 -0700 (MST) (envelope-from freebsd@dreamchaser.org) Subject: Re: Subject: Thunderbird causing system crash, need guidance To: Matthew Seaman , freebsd-questions@freebsd.org References: <201712110045.vBB0jCTQ078476@nightmare.dreamchaser.org> <38e2ef70-fa1b-25bf-4447-752006418d0a@dreamchaser.org> <460ae512-89b6-d09f-b567-fefff373b087@FreeBSD.org> Reply-To: freebsd@dreamchaser.org From: Gary Aitken Message-ID: <2ae72a98-9584-aee2-bb41-31dbc31250f8@dreamchaser.org> Date: Mon, 11 Dec 2017 18:27:35 -0700 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <460ae512-89b6-d09f-b567-fefff373b087@FreeBSD.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (nightmare.dreamchaser.org [192.168.151.101]); Mon, 11 Dec 2017 18:28:08 -0700 (MST) X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 12 Dec 2017 01:28:16 -0000 On 12/11/17 00:56, Matthew Seaman wrote: > On 11/12/2017 04:56, Gary Aitken wrote: > >>>> md99 none swap sw,file=/usr/swap/swap,late > 0 0 > >>> Your swap configuration is also mostly likely silly.  If you need >>> more performance, that's not the way to do it. > >> Can you explain or point me to an explanation for this comment?  It >> looks to me like what's shown in the EXAMPLES section of "man fstab". > > You're swapping to a file-backed memory device, which is not the best > choice for performance. The best choice is to swap to raw partitions on > your hard drives. Having several disks with a swap partition on each > can help, as it allows you to spread the IO load over several devices, > but that's a marginal gain and not necessary in general. > > The reasoning being that you're involving all of the kernel machinery to > support filesystem IO for what is meant to be the very low-level and > simplified operation of paging memory in and out of swap. > > Yes, you can create a file-backed swap area, but just because you can > doesn't mean you should. Creating a file-backed swap is useful in > special cases, like you're working on that part of the kernel and need > to test adding or removing swap devices, or you're trying to cope with > some exceptional process that is really far too large for your system to > handle. > > Ideally nowadays you should have enough RAM to contain all of your > active processes without needing to swap, so the whole point should > really be moot. Many thanks for the clarification. Gary