From owner-freebsd-current@FreeBSD.ORG Sun Oct 7 15:28:18 2012 Return-Path: Delivered-To: current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 9E4991065670 for ; Sun, 7 Oct 2012 15:28:18 +0000 (UTC) (envelope-from levitch@iglou.com) Received: from rdsmtp.iglou.com (rdsmtp.iglou.com [192.107.41.63]) by mx1.freebsd.org (Postfix) with ESMTP id 5692A8FC0C for ; Sun, 7 Oct 2012 15:28:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=iglou.com; s=alpha; h=Content-Type:MIME-Version:References:Message-ID:In-Reply-To:Subject:cc:To:From:Date; bh=ru4Q+DQbpe5yelnI18aWP9fYw8A4C6JT31r3csTcWLc=; b=kMBKhdxsryMOQcWam5ZleMifKFhyOcgEzuKnWMn0OhBlL0AVwEkCWj4gOyHlN/8cPD1qZCAzM4UVJ2VvmEGRbrV4ex8gf6yRfgi6r6/C4DTC6yVR92ScpFHuJH0/bXFoW4ZNSZfETPe8dlmnwMIFv7nKUoDJzjhNT0iM0VCQmwc=; Received: from iglou1.iglou.com ([192.107.41.3]:62586 helo=mail.iglou.com) by rdsmtp.iglou.com with esmtpa (Exim MTA/8.19.3) (envelope-from ) id 1TKsm2-00018E-UJ by authid with igloumta_auth for current@freebsd.org; Sun, 07 Oct 2012 11:28:10 -0400 Received: from shell1.iglou.com ([192.107.41.17]:57682 helo=shell1) by mail.iglou.com with esmtps (TLS cipher TLSv1:AES256-SHA:256) (Exim MTA/8.19.3) (envelope-from ) id 1TKsm1-0005zU-MZ; Sun, 07 Oct 2012 11:28:09 -0400 Date: Sun, 7 Oct 2012 11:28:09 -0400 (EDT) From: Darrel X-X-Sender: levitch@shell1 To: Peter Jeremy In-Reply-To: <20121007015251.GB22291@server.rulingia.com> Message-ID: References: <20121007015251.GB22291@server.rulingia.com> User-Agent: Alpine 2.00 (GSO 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Originating-IP: 192.107.41.17 X-IgLou-Customer: 3cb6f76205bd20f518810676a67a982b X-Mailman-Approved-At: Sun, 07 Oct 2012 17:48:44 +0000 Cc: Sergey Kandaurov , current@freebsd.org Subject: Re: memory warnings r240891 | dmesgg X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 07 Oct 2012 15:28:18 -0000 >>> warning: total configured swap (2621440 pages) exceeds maximum >>> recommended amount (1852656 pages). > ... >> This is because kernel needs some memory to manage swap too. >> Currently for amd64 this roughly reduces to the following rule >> (My apologies in advance for the extra simplification): >> >> 100MB RAM per 800MB swap space. > > That is oversimplified to the point of being wrong. As of HEAD > r239255 and 9-stable r240097, there's no longer a limit on amd64. The > limit is still required on 32-bit architectures due to the limited KVA > available. > The original poster; i.e., me, copied the error message directly from amd64 running r240891. Here is some information after /etc/fstab swap was left untouched and zfs swap was reduced: (11:14) dmesg | grep recommended warning: total configured swap (1854464 pages) exceeds maximum recommended amount (1852656 pages). (11:19) swapinfo -h Device 1K-blocks Used Avail Capacity /dev/zvol/bigD/swap 1126400 94M 1G 9% /dev/gpt/swap0.eli 3145728 93M 2.9G 3% /dev/gpt/swap1.eli 3145728 94M 2.9G 3% Total 7417856 282M 6.8G 4% I guess that we are seeing some swap actually in use now because buildkernel is running; i.e., > r241254. > The actual KVA requirements (RAM is only allocated when the swap space > is actually used) is about 5MB KVA per 1GB swap. The default swzone > for i386 was 32MiB - which is sufficient for ~7GB swap (the 1852656 > pages reported above) and was increased to 34.5MB for i386 in r239730 > to support ~8GB swap (this is also in r240097). (It's all approximate > because of the way swap space is allocated using struct swblock). > > See the thread starting > http://lists.freebsd.org/pipermail/freebsd-current/2012-August/035839.html > for more details. > Interesting. Yet from my first reading it seems like the limit was actually a warning and the warning still exists in amd64. I wonder if there is to run other than swapinfo, to actually see if swapinfo is correct in reporting that the swap in use is actually identical in size from each disk of the mirror and also 94M precisely from zfs swap? Thank you, Darrel