From owner-freebsd-current@FreeBSD.ORG Wed Aug 22 06:56:07 2007 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0E3CF16A41A for ; Wed, 22 Aug 2007 06:56:07 +0000 (UTC) (envelope-from stefan.lambrev@moneybookers.com) Received: from blah.sun-fish.com (blah.sun-fish.com [217.18.249.150]) by mx1.freebsd.org (Postfix) with ESMTP id BBCFB13C457 for ; Wed, 22 Aug 2007 06:56:06 +0000 (UTC) (envelope-from stefan.lambrev@moneybookers.com) Received: from blah.sun-fish.com (localhost [127.0.0.1]) by blah.sun-fish.com (Postfix) with ESMTP id 34A9A1B10EE7; Wed, 22 Aug 2007 08:56:05 +0200 (CEST) Received: from hater.cmotd.com (hater.cmotd.com [192.168.3.125]) by blah.sun-fish.com (Postfix) with ESMTP id 319881B10EE0; Wed, 22 Aug 2007 08:56:05 +0200 (CEST) Message-ID: <46CBDE05.2030007@moneybookers.com> Date: Wed, 22 Aug 2007 09:56:05 +0300 From: Stefan Lambrev User-Agent: Thunderbird 2.0.0.4pre (X11/20070711) MIME-Version: 1.0 To: Kris Kennaway References: <46C9B99C.1060403@moneybookers.com> <46CA951D.1060303@moneybookers.com> <20070821163729.GA91485@rot26.obsecurity.org> In-Reply-To: <20070821163729.GA91485@rot26.obsecurity.org> Content-Type: text/plain; charset=windows-1251; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: ClamAV using ClamSMTP on BLAH Cc: Eric Kjeldergaard , freebsd-current@freebsd.org Subject: Re: kernel panic with memory disks 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: Wed, 22 Aug 2007 06:56:07 -0000 Kris Kennaway wrote: > On Tue, Aug 21, 2007 at 10:32:45AM +0300, Stefan Lambrev wrote: > >> Hello, >> >> Eric Kjeldergaard wrote: >> >>> On 20/08/07, Stefan Lambrev wrote: >>> >>> >>>> Hello, >>>> >>>> I do not know if this is know behavior, and I know that 6.2 panic if the >>>> memory disk got full, >>>> but on 7-current the panic is before the disk got full. >>>> >>>> Here is what I do: >>>> >>>> mdconfig -a -t malloc -s 800m >>>> newfs /dev/md0 >>>> mount /dev/md0 /mnt >>>> cp 600mb.file /mnt >>>> >>>> >>> -t type >>> Select the type of the memory disk. >>> >>> malloc Storage for this type of memory disk is allocated >>> with >>> malloc(9). This limits the size to the malloc bucket >>> limit in the kernel. If the -o reserve option is not >>> set, creating and filling a large malloc-backed >>> memory >>> disk is a very easy way to panic a system. >>> -- mdconfig(8) >>> >>> >>> >> I really should read manuals more carefully :) Thanks for the information. >> >> Just one more question - to prevent panic I should use "-o reserve" and >> have to increase: >> vfs.maxmallocbufspace >> vfs.bufmallocspace >> > > No, you should use -o swap. Where did it tell you to change the > sysctls? > > Kris > Nowhere just guessing. I just needed one big file in the memory to ignore the slowness of hard drives, to run few small benchmarks :) I did this using tmpfs, but it act just like "-t swap" :) Btw the confusion comes from the manual of mdconfig where it states: swap Swap space is used to back this memory disk. and I thought that type swap is always stored on the hard drives. and md(4) explains it a lot better: swap Backing store is allocated from buffer memory. Pages get pushed out to the swap when the system is under memory pressure, other- wise they stay in the operating memory. Using swap backing is generally preferable over malloc backing. -- Best Wishes, Stefan Lambrev ICQ# 24134177