From owner-freebsd-questions@freebsd.org Mon Jul 10 15:34:08 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 D73CDDAAEB8 for ; Mon, 10 Jul 2017 15:34:08 +0000 (UTC) (envelope-from 4250.10.freebsd-questions=freebsd.org@email-od.com) Received: from bca5.email-od.com (bca5.email-od.com [207.246.239.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id ACB78689F8 for ; Mon, 10 Jul 2017 15:34:08 +0000 (UTC) (envelope-from 4250.10.freebsd-questions=freebsd.org@email-od.com) DKIM-Signature: v=1; a=rsa-sha256; d=email-od.com;i=@email-od.com;s=dkim; c=relaxed/relaxed; q=dns/txt; t=1499700840; x=1502292840; h=x-thread-info:date:from:to:cc:subject:message-id:in-reply-to:references:mime-version:content-type:content-transfer-encoding; bh=WK7PuBcKKS1qfxUodrPEpse+vd1xrl2dwTJS9JLxPI0=; b=LR/1GksmUTsoNXTuNqAPGU5hSrqWyFEv6WOxZdl40/XRVIy/SO2+YsMlKx0N2ec5jCIfgJnw+rGEklQ7OHpijWAUQ9vbCM7nvDurC07ZlOJsWdxVzIM7pHZh2RuVPxqvwOmPCUJQvQeiPeCxlTAY5X8BMTMxS0JoV6P83qMoP4A= X-Thread-Info: NDI1MC4xMi5kNzAwMDAwMDUzZDU1ZC5mcmVlYnNkLXF1ZXN0aW9ucz1mcmVlYnNkLm9yZw== Received: from r3.us-east.aws.in.socketlabs.com (r3.us-east.aws.in.socketlabs.com [54.165.229.15]) by bca2.email-od.com with ESMTP(version=Tls12 cipher=Aes256 bits=256); Mon, 10 Jul 2017 11:33:57 -0400 Received: from smtp.lan.sohara.org (EMTPY [89.127.62.20]) by r3.us-east.aws.in.socketlabs.com with ESMTP(version=Tls12 cipher=Aes256 bits=256); Mon, 10 Jul 2017 11:34:03 -0400 Received: from [192.168.63.1] (helo=steve.lan.sohara.org) by smtp.lan.sohara.org with smtp (Exim 4.89 (FreeBSD)) (envelope-from ) id 1dUaiD-000C58-LM; Mon, 10 Jul 2017 15:35:01 +0000 Date: Mon, 10 Jul 2017 16:33:51 +0100 From: Steve O'Hara-Smith To: freebsd-questions@freebsd.org Cc: galtsev@kicp.uchicago.edu Subject: Re: Unusual Question Message-Id: <20170710163351.a347713b6d8f64e141d1d9f2@sohara.org> In-Reply-To: <26749.128.135.52.6.1499700385.squirrel@cosmo.uchicago.edu> References: <888578F8-AD68-4993-823C-152789F3C929@mail.sermon-archive.info> <52627.76.193.16.95.1499645892.squirrel@cosmo.uchicago.edu> <20170710052228.GA2338@c720-r314251> <20170710090547.15ee3afc07c09955ba621ae1@sohara.org> <26749.128.135.52.6.1499700385.squirrel@cosmo.uchicago.edu> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; amd64-portbld-freebsd10.3) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 10 Jul 2017 15:34:08 -0000 On Mon, 10 Jul 2017 10:26:25 -0500 (CDT) "Valeri Galtsev" wrote: > I believe, the kernel addresses swap not by addressing sectors on raw > device covering the whole physical drive, but as "relative sectors" > through swap partition device. Sure, but I doubt it reads the partition table again after it has it read the first time, that's an obvious thing to cache. > If I'm right, once drive partition table is > gone reading swap will fail and panic kernel. I doubt it, the partition table should be cached in memory, otherwise yes that would panic the kernel, but reading the partition table every time a page needs swapping in would be stupidly inefficient so I don't believe it happens. > But the suggestion you made in another post: to make Not my suggestion, it's a sensible one but I don't think it's needed. -- Steve O'Hara-Smith | Directable Mirror Arrays C:>WIN | A better way to focus the sun The computer obeys and wins. | licences available see You lose and Bill collects. | http://www.sohara.org/