From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08E4DC76191 for ; Thu, 18 Jul 2019 05:18:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D3DBA2173E for ; Thu, 18 Jul 2019 05:18:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726827AbfGRFSv (ORCPT ); Thu, 18 Jul 2019 01:18:51 -0400 Received: from smtprelay0002.hostedemail.com ([216.40.44.2]:44853 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725959AbfGRFSv (ORCPT ); Thu, 18 Jul 2019 01:18:51 -0400 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay04.hostedemail.com (Postfix) with ESMTP id C4B22180A68BF; Thu, 18 Jul 2019 05:18:49 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: power11_12a7847651600 X-Filterd-Recvd-Size: 2231 Received: from XPS-9350 (cpe-23-242-196-136.socal.res.rr.com [23.242.196.136]) (Authenticated sender: joe@perches.com) by omf05.hostedemail.com (Postfix) with ESMTPA; Thu, 18 Jul 2019 05:18:48 +0000 (UTC) Message-ID: <9eda0e29f524275a217411ea81352271b782baa4.camel@perches.com> Subject: Re: [PATCH] KVM: x86/vPMU: refine kvm_pmu err msg when event creation failed From: Joe Perches To: Like Xu , Paolo Bonzini , Avi Kivity Cc: kvm@vger.kernel.org, Gleb Natapov , like.xu@linux.inetl.com, linux-kernel@vger.kernel.org Date: Wed, 17 Jul 2019 22:18:46 -0700 In-Reply-To: <20190718044914.35631-1-like.xu@linux.intel.com> References: <20190718044914.35631-1-like.xu@linux.intel.com> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.30.5-0ubuntu0.18.10.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2019-07-18 at 12:49 +0800, Like Xu wrote: > If a perf_event creation fails due to any reason of the host perf > subsystem, it has no chance to log the corresponding event for guest > which may cause abnormal sampling data in guest result. In debug mode, > this message helps to understand the state of vPMC and we should not > limit the number of occurrences. [] > diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c [] > @@ -131,8 +131,8 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type, > intr ? kvm_perf_overflow_intr : > kvm_perf_overflow, pmc); > if (IS_ERR(event)) { > - printk_once("kvm_pmu: event creation failed %ld\n", > - PTR_ERR(event)); > + pr_debug("kvm_pmu: event creation failed %ld\n for pmc->idx = %d", > + PTR_ERR(event), pmc->idx); Perhaps this was written as printk_once to avoid spamming the log with repeated messages. Maybe this should use pr_debug_ratelimited. (and it should also have a \n termination like:) pr_debug_ratelimited("kvm_pmu: event creation failed %ld for pmc->idx = %d\n", PTR_ERR(event), pmc->idx); Perhaps Avi Kivity remembers why he wrote it this way. https://lore.kernel.org/kvm/1305129333-7456-6-git-send-email-avi@redhat.com/