From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH] KVM: MMU: Inform users of mmio generation wraparound Date: Thu, 20 Jun 2013 15:14:42 +0200 Message-ID: <51C30042.5030505@redhat.com> References: <20130620175914.4e4f9eb3.yoshikawa_takuya_b1@lab.ntt.co.jp> <51C2E0AA.7060404@redhat.com> <20130620114504.GG5832@redhat.com> <20130620212837.185c5d4f5a9adbbd44c6f1ad@gmail.com> <20130620125438.GM5832@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Takuya Yoshikawa , Takuya Yoshikawa , kvm@vger.kernel.org, xiaoguangrong@linux.vnet.ibm.com To: Gleb Natapov Return-path: Received: from mx1.redhat.com ([209.132.183.28]:1610 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754273Ab3FTNPR (ORCPT ); Thu, 20 Jun 2013 09:15:17 -0400 In-Reply-To: <20130620125438.GM5832@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Il 20/06/2013 14:54, Gleb Natapov ha scritto: >> If they see mysterious peformance problems induced by this wraparound, the only >> way to know the cause later is by this kind of information in the syslog. >> So even the first wraparound may better be printed out IMO. > Think about starting hundreds VMs on a freshly booted host. You will see > hundreds of those pretty quickly. With the change I made to Xiao's patch (changing -13 to -150) you won't see it immediately after startup, but the first wraparound may still come very soon with a loop that reads the ROM. (The second takes 5 minutes). >> I want to let administrators know the cause if possible, any better way? >> > Not that I can think of. Paolo what about print_once() and ignore first > wraparound? printk_ratelimited is enough, even without ignoring the first wraparound. It will handle the case of multiple VMs too. Paolo