From owner-freebsd-arm@freebsd.org Wed Jul 18 19:09:37 2018 Return-Path: Delivered-To: freebsd-arm@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 80C8F102E83C for ; Wed, 18 Jul 2018 19:09:37 +0000 (UTC) (envelope-from fbsd@www.zefox.net) Received: from www.zefox.net (www.zefox.net [50.1.20.27]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "www.zefox.org", Issuer "www.zefox.org" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id CB34088AF4 for ; Wed, 18 Jul 2018 19:09:36 +0000 (UTC) (envelope-from fbsd@www.zefox.net) Received: from www.zefox.net (localhost [127.0.0.1]) by www.zefox.net (8.15.2/8.15.2) with ESMTPS id w6IJ9qgH027732 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Wed, 18 Jul 2018 12:09:53 -0700 (PDT) (envelope-from fbsd@www.zefox.net) Received: (from fbsd@localhost) by www.zefox.net (8.15.2/8.15.2/Submit) id w6IJ9qHL027731; Wed, 18 Jul 2018 12:09:52 -0700 (PDT) (envelope-from fbsd) Date: Wed, 18 Jul 2018 12:09:51 -0700 From: bob prohaska To: Mark Millard Cc: freebsd-arm@freebsd.org Subject: Re: RPI3 swap experiments Message-ID: <20180718190951.GB27481@www.zefox.net> References: <20180629233937.GC35717@www.zefox.net> <0f137e06-214a-3e8c-a216-f061ec04ac2c@sentry.org> <20180630005145.GA43801@www.zefox.net> <6f3406e2-71f3-d0c2-2b65-703e1a1d3c25@sentry.org> <8e92b2b7-da61-3efb-7231-9fac76b2c1d4@sentry.org> <2deaaec3-f78f-0b09-5ca7-27e14c6979f9@sentry.org> <20180704004554.GA61273@www.zefox.net> <20180718060650.GA24566@www.zefox.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.27 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 18 Jul 2018 19:09:37 -0000 On Wed, Jul 18, 2018 at 07:42:13AM -0700, Mark Millard wrote: > > > On 2018-Jul-17, at 11:06 PM, bob prohaska wrote: > > > It appears that some progress has been made in getting swap working reasonably > > on the RPI3. A -j4 buildworld attempt running r336356 to compile 336431 failed > > with "out of swap" but the worst read and write delays were less than 5 seconds, > > a marked improvement over previous examples. > > Attributing the time variations that have been observed mostly to FreeBSD and not > mostly to the device at issue seems to have little or no evidence to support it. > Possibly a fair objection. This test is with a USB3.0 flash drive. I'll repeat soon as possible with a USB3.1 device, which in the past reported much greater (15 second) delays. > > In this case swap was split, 2 each 1GB partitions on USB flash plus 1 GB on the > > microSD card. Previous attempts using 3 each 1 GB partitions on USB flash have been > > repeatedly successful, while a single attempt using 3 each 1GB partitions on microSD > > failed. > > The more swap partitions (or space?) not on a /dev/mmcsd0s* the less of the > activity that /dev/mmcsd0 handles and likely the more time it tends to have > between explicit operations to do internal housekeeping before the next > explicit operation. > > So the better approximation to not using /dev/mmcsd0 at all might not be > all that much of a surprise at having less of a problem on the device > (or a problem less often). > In earlier tests (same card type) putting _all_ swap on microSD (along with /tmp) avoided OOMA kills. Dependable mischief seems to come when swap is on both microSD and USB. It's understood that USB and Ethernet share I/O hardware, but I thought microSD was at least somewhat independent. Is this wrong? Thanks for reading, bob prohaska