From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-we0-f174.google.com ([74.125.82.174]:47618 "EHLO mail-we0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752928Ab2AFVdL (ORCPT ); Fri, 6 Jan 2012 16:33:11 -0500 Message-ID: <1325892770.4847.1.camel@lappy> Subject: Re: Boot regression caused by commit 6829a048 From: Sasha Levin To: Trond Myklebust Cc: chuck.lever@oracle.com, linux@razik.name, Pekka Enberg , linux-nfs , linux-kernel Date: Sat, 07 Jan 2012 01:32:50 +0200 In-Reply-To: <1325874404.32470.6.camel@lade.trondhjem.org> References: <1325871176.4629.35.camel@lappy> <1325874404.32470.6.camel@lade.trondhjem.org> Content-Type: text/plain; charset="us-ascii" Mime-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Fri, 2012-01-06 at 13:26 -0500, Trond Myklebust wrote: > On Fri, 2012-01-06 at 19:32 +0200, Sasha Levin wrote: > > Hi all, > > > > I've noticed a boot regression caused by commit 6829a048 ("NFS: Retry > > mounting NFSROOT") which has increased boot time by 95 seconds. > > > > The scenario is as follows: > > - A virtual guest running under the KVM tool. > > - Guest is using kernel automatic IP DHCP configuration ("ip=dhcp"). > > - Guest is booting from a 9p device (which is not detected as block, > > and gets mounted after NFS tries to do its mounts). > > - No NFS server at all, no NFS parameters passed to the guest kernel. > > > > Under this scenario, theres an additional 95 second delay before NFS > > fails and tries to boot using 9p: > > > > [...] > > [ 6.505269] md: autorun ... > > [ 6.506954] md: ... autorun DONE. > > [ 101.522716] VFS: Unable to mount root fs via NFS, trying floppy. > > [ 101.534499] VFS: Mounted root (9p filesystem) on device 0:18. > > [...] > > Can't you avoid the whole NFS root mount attempt by setting "root=2:0" > directly instead of relying on 'mount_root' to do it for you? I am specifying root and root parameters fully: "root=/dev/root rw rootflags=rw,trans=virtio,version=9p2000.L rootfstype=9p" Actually, I'm not sure why NFS comes to play at all in this case. -- Sasha.