From owner-freebsd-arm@freebsd.org Wed Aug 15 13:03:46 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 5D2E01083C05 for ; Wed, 15 Aug 2018 13:03:46 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) (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 B521E8B69E for ; Wed, 15 Aug 2018 13:03:45 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from tom.home (kib@localhost [127.0.0.1]) by kib.kiev.ua (8.15.2/8.15.2) with ESMTPS id w7FD3Uxi007518 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Wed, 15 Aug 2018 16:03:33 +0300 (EEST) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua w7FD3Uxi007518 Received: (from kostik@localhost) by tom.home (8.15.2/8.15.2/Submit) id w7FD3UEU007517; Wed, 15 Aug 2018 16:03:30 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Wed, 15 Aug 2018 16:03:30 +0300 From: Konstantin Belousov To: "Jedi Tek'Unum" , freebsd-arm@freebsd.org Subject: Re: RPI3 swap experiments (grace under pressure) Message-ID: <20180815130330.GY2340@kib.kiev.ua> References: <20180813021226.GA46750@www.zefox.net> <0D8B9A29-DD95-4FA3-8F7D-4B85A3BB54D7@yahoo.com> <20180813185350.GA47132@www.zefox.net> <20180814014226.GA50013@www.zefox.net> <02fe39af-a02c-fb6a-70b0-da3b7fd06c22@goodgas.com.au> <20180814213107.GA51051@www.zefox.net> <20180815125513.GT97145@funkthat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180815125513.GT97145@funkthat.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Spam-Status: No, score=-2.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FREEMAIL_FROM,NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on tom.home 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, 15 Aug 2018 13:03:46 -0000 On Wed, Aug 15, 2018 at 05:55:13AM -0700, John-Mark Gurney wrote: > Jedi Tek'Unum wrote this message on Tue, Aug 14, 2018 at 17:17 -0500: > > I have one question??? when was the last time anyone saw Solaris kill a process because the system was under memory stress? In my experience, NEVER! And I wouldn???t say that the system became unreasonably unresponsive either. > > At least for Solaris 2.5, they would not allow overallocation of swap... > If you had pages that could be modified, you had to have enough swap > storage to store a copy of those pages... If you didn't, you'd get an > out of memory error when trying to allocate the memory, such as forking, > sbrk or mmap'ing... > > FreeBSD has long allowed overallocation of swap because w/ early > computers most people didn't have enough storage to handle it, and > most memory won't be used... There is a knob to disable overcommit in FreeBSD, see vm.overcommit description in tuning(7). It is not very popular exactly because forking large process requires reservation of twice memory comparing with the real use. I believe that the option is exercised by stress2, but I did not heard about real-life usage, except my own long time ago.