From owner-freebsd-arm@freebsd.org Sat Mar 3 01:18:18 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 448A9F34648 for ; Sat, 3 Mar 2018 01:18:18 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: from mail-it0-x22c.google.com (mail-it0-x22c.google.com [IPv6:2607:f8b0:4001:c0b::22c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id CA44C847F5 for ; Sat, 3 Mar 2018 01:18:17 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: by mail-it0-x22c.google.com with SMTP id l187so3970759ith.4 for ; Fri, 02 Mar 2018 17:18:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bsdimp-com.20150623.gappssmtp.com; s=20150623; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=rC9r1xENAhPGeQcXeaJFnowK8l4Tho5k5wZdeFvAXSU=; b=VhXnsvPz2/rnL3WI8dxgjwH1w0qLqGhitr35T1yhn46uyTqeyfABZPwTx5L8njQnfJ /hr3qMSgvamnBTP8p1A1MgS37ZHpbfhYmCIB0FnEXvUOl005csPWb0NwVqliehQeEarn aRgnPGf5pix0LDMsV5M3bFmGezAVCMFA/DpkJPD/oX4gG3A+L7ZK9DFDhjoQJcLse9Wa 2PIQiRIg0hoiLjEyAH5asnBxqM/Dqs2mLE5Sn/tg3apsMzodBl491XC0Pd7cDuQyVmot JzGZ8wBY+HrQjWmKhZMJhiAQwAIPGk7RhmbesV0mIpiMm16qLJ8mbPpKXfuJL5vDIJhP zBhQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc; bh=rC9r1xENAhPGeQcXeaJFnowK8l4Tho5k5wZdeFvAXSU=; b=cVhMbwEiPyS3MoA/yvmtjoYuAYkijuzzcQSneS5wsmW3lThIDHlu9j4P83Lxz/Yl6X MvPCXbehsn9a/kSn81abQwqCDpskH16lnpqhd2mTalw322CVCN/E+1yAYepFnajidKtY XpgPRD+y2GfthAqSb7iS9DU0PSeFT+/4+KQh2puYtihkc5eGSyd4QyWV7OtmvPsnBzl1 RWsnq4i5887+jVnpYAudzm487UstqdbUR40BMITnxL7+WVZF7HEDfOBF73H0s37vMyiR QwfRhtk0AB2YOVKAe3RdOwmySEQN3QknwzEe08MUKQUrFTJyvLhBtpnvAxq9gz5f2oJV ++ww== X-Gm-Message-State: AElRT7ESIvhTsUpz/b1XQdnYrB1oAUWGcNej0uWDfkjCEmu4CGjSs8kj 3+8yaKKyjcEj6ci8T87wFJ76ahyQDdf69FsltMJAag== X-Google-Smtp-Source: AG47ELuhWC/4+o8cQmvbtKv/fO1R01y3vYK6qbKfQZYFa1X6PexBcNm9dZ0YPeUQLQsqe9Mpu8k9cLAfXoUx7u2EAxI= X-Received: by 10.36.16.147 with SMTP id 141mr5056080ity.73.1520039897133; Fri, 02 Mar 2018 17:18:17 -0800 (PST) MIME-Version: 1.0 Sender: wlosh@bsdimp.com Received: by 10.79.203.196 with HTTP; Fri, 2 Mar 2018 17:18:16 -0800 (PST) X-Originating-IP: [2603:300b:6:5100:1052:acc7:f9de:2b6d] In-Reply-To: <20180303004315.GB37148@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> <1520010957.23690.10.camel@freebsd.org> <20180303004315.GB37148@www.zefox.net> From: Warner Losh Date: Fri, 2 Mar 2018 18:18:16 -0700 X-Google-Sender-Auth: 6OcKS5QZ0I2L9bh2JaeEOC_67DU Message-ID: Subject: Re: Is maximum swap usage tunable? To: bob prohaska Cc: Ian Lepore , Mike , "freebsd-arm@freebsd.org" Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.25 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: Sat, 03 Mar 2018 01:18:18 -0000 On Fri, Mar 2, 2018 at 5:43 PM, bob prohaska wrote: > On Fri, Mar 02, 2018 at 10:15:57AM -0700, Ian Lepore wrote: > > > You forgot a cause: (5) swap is on an sdcard where taking 30-90 seconds > > to complete an IO is "normal". > > > FWIW, the Sandisk Extreme USB flash drive is claimed to be considerably > faster than that, ~2MB/sec random write, at least per > http://usb.userbenchmark.com/SanDisk-Extreme-USB-30-16GB/Rating/1301 > One hopes(!) that the microSD cards of the same name are simlar. Hope in one hand and spit in the other and see which one gets wet first :) The problem isn't the steady-state happy-state streaming pictures/video to the card. The problem is that sometimes the "long tail" times for the I/O for pathological cases can be seconds, or tends of seconds. It doesn't take too many of those high-latency I/Os to really screw up the system.... SD card FTLs are 'go fast for streaming video / pictures, suck slow for everything else'. Consumer grade SSDs, though they also have kinda crappy FTLs, aren't anywhere near that bad. Warner