From owner-freebsd-arm@freebsd.org Sun Mar 4 18:28:35 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 C693EF2519F for ; Sun, 4 Mar 2018 18:28:35 +0000 (UTC) (envelope-from fbsd@www.zefox.net) Received: from www.zefox.net (www.zefox.net [69.239.235.194]) (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 194796855B for ; Sun, 4 Mar 2018 18:28:34 +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 w24ISWUi046357 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Sun, 4 Mar 2018 10:28:32 -0800 (PST) (envelope-from fbsd@www.zefox.net) Received: (from fbsd@localhost) by www.zefox.net (8.15.2/8.15.2/Submit) id w24ISVhV046356; Sun, 4 Mar 2018 10:28:31 -0800 (PST) (envelope-from fbsd) Date: Sun, 4 Mar 2018 10:28:31 -0800 From: bob prohaska To: Warner Losh Cc: Mike , "freebsd-arm@freebsd.org" , bob prohaska Subject: Re: Is maximum swap usage tunable? Message-ID: <20180304182831.GA44154@www.zefox.net> References: <20180228170311.GA26187@www.zefox.net> <20180228185517.GB26187@www.zefox.net> <8f422161-885e-aa91-eacd-018540222d65@mgm51.com> <20180228214301.GA29481@www.zefox.net> <20180303162605.GA41874@www.zefox.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180303162605.GA41874@www.zefox.net> User-Agent: Mutt/1.5.24 (2015-08-30) X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 04 Mar 2018 18:28:36 -0000 On Sat, Mar 03, 2018 at 08:26:05AM -0800, bob prohaska wrote: > > Is there some sort of experiment which can distinguish hardware delays > from software delays? For example, would logging gstat output shed any > light? > For lack of any better ideas, I tried running make -j2 -DNO_CLEAN buildworld > buildworld.log && make -j2 -DNO_CLEAN KERNCONF= ZEFOX buildkernel > buildkernel.log while also running gstat -a -B -I 10s > j2_gstat.log & in another ssh session In due course the console reported FreeBSD/arm64 (www.zefox.org) (ttyu0) login: Mar 4 09:28:30 www kernel: pid 9310 (c++), uid 0, was killed: out of swap space as expected. However, a grep of j2_gstat revealed a maximum write delay of 30ms/w for swap on microSD. Swap on USB flash is slower, but still generally under 100 ms. Only a handful of widely spaced delays exceeded 200 ms/w. The worst-case events were dT: 10.002s w: 10.000s L(q) ops/s r/s kBps ms/r w/s kBps ms/w %busy Name 0 6 0 0 0.0 6 113 14.6 3.3 da0b 0 4 0 0 0.0 4 48 29.0 3.1 da0b 0 9 5 79 3.0 5 47 7.9 2.6 da0b 4 8 0 0 0.0 8 99 67.5 32.5 da0b 0 1 0 13 5.6 1 28 5674 88.3 da0b 0 0 0 0 0.0 0 38 18.6 0.3 da0b 0 1 1 9 2.8 0 0 0.0 0.2 da0b 0 1 1 26 5.1 0 0 0.0 0.4 da0b 0 0 0 3 2.6 0 0 0.0 0.1 da0b 0 1 1 9 161.8 0 0 0.0 14.3 da0b No "indefinite delay" warnings were presented on the console. uname -a reports r329893, sources are at 330383. I hope this is useful information, bob prohaska