From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1EMvNj-0003XD-0l for qemu-devel@nongnu.org; Tue, 04 Oct 2005 18:35:31 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1EMvNi-0003We-4q for qemu-devel@nongnu.org; Tue, 04 Oct 2005 18:35:30 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1EMvNh-0003Wb-W4 for qemu-devel@nongnu.org; Tue, 04 Oct 2005 18:35:30 -0400 Received: from [213.165.64.20] (helo=mail.gmx.net) by monty-python.gnu.org with smtp (Exim 4.34) id 1EMvNh-0006Nb-Un for qemu-devel@nongnu.org; Tue, 04 Oct 2005 18:35:30 -0400 Subject: Re: [Qemu-devel] bad performance accessing nfs exports on qemu host From: Henning Sprang In-Reply-To: <1128433274.3764.50.camel@gnomehost.> References: <1128433274.3764.50.camel@gnomehost.> Content-Type: text/plain Date: Wed, 05 Oct 2005 00:35:22 +0200 Message-Id: <1128465323.7577.5.camel@montego.lazy> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Hi, I found some answers/help to my questions by further looking: On Tue, 2005-10-04 at 15:41 +0200, Henning Sprang wrote: > Hi, > First of all, this is more a question about qemu usage, not development, > but the link to the qemu user forum on the qemu website > ( http://www.dad-answers.com/qemu-forum/index.php )is broken (404), and > I don't see any other place to get qemu help for users. If there is a > better place for this question, please tell me so. The Link on the website is really broken, but I found the user forum on http://qemu.dad-answers.com/ - it could help users and developers a lot if that link could be fixed. I also wonder why there is no Mailing list for users. > > I am trying to use qemu for helping me with the development of an > automatic installation software for Debian Linux (FAI, that is). > > Therefore I need a qemu guest system (FAI install client) mounting it's > root file system from an nfs server on the qemu host, and unpacking a > tar.gz file from that root into a directory from it's "local" virtual > harddisk. > > While all the other services involved (dhcp, dns, ssh) seem to work with > no problems, I have serious performance trouble with NFS when I want to > copy or unzip the file mentioned. I get a mount, and, when copying the > file, the whole qemu guest system turns incredibly slow, and it takes > approximately half an hour to copy a 40M file from the nfsroot to it's > local disk. In that time, also any command given on the qemu guest's > shell executes extremly slow. Copying files with ftp is much faster. > There is not big CPU load or anything to be seen on neither guest or > host. So finally everything works, and my automatic install comes to an > end, but with a very long delay, taking a sum of more than an hour, of > which most of the seems to be spent on just copying a 40M file. > I found a workaround for that - when I enable NFS over TCP by giving my install client a line like this with dhcp: option root-path "/usr/lib/fai/nfsroot,rsize=8192,wsize=8192,acregmin=1800,acregmax=1800,acdirmin=1800,acdirmax=1800,tcp"; - most important is the last part "tcp" - then everything goes much much faster. It seems like qemu doesn't work well for udp packets, maybe the developers have a better idea and explanation for that?! Anyway, have a nice day - mine is made by this great thing I found, now I can use qemu for real nice testing of FAI installation without spending lots of money for hardware. Henning