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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=ham 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 D2118C433E6 for ; Wed, 27 Jan 2021 18:29:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 94FFA64DAB for ; Wed, 27 Jan 2021 18:29:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236678AbhA0S3Q (ORCPT ); Wed, 27 Jan 2021 13:29:16 -0500 Received: from smtprelay0049.hostedemail.com ([216.40.44.49]:49964 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S236548AbhA0S3M (ORCPT ); Wed, 27 Jan 2021 13:29:12 -0500 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay07.hostedemail.com (Postfix) with ESMTP id 6E10F181D303A; Wed, 27 Jan 2021 18:28:30 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: ocean53_4812ee027599 X-Filterd-Recvd-Size: 2375 Received: from [192.168.1.159] (unknown [47.151.137.21]) (Authenticated sender: joe@perches.com) by omf07.hostedemail.com (Postfix) with ESMTPA; Wed, 27 Jan 2021 18:28:27 +0000 (UTC) Message-ID: <10805faed4d19ce842cef277b74479a883514afe.camel@perches.com> Subject: Re: [PATCH] KVM: x86/mmu: Add '__func__' in rmap_printk() From: Joe Perches To: Paolo Bonzini , Stephen Zhang , seanjc@google.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 27 Jan 2021 10:28:26 -0800 In-Reply-To: <854ee6dc-2299-3897-c4af-3f7058f195af@redhat.com> References: <1611713325-3591-1-git-send-email-stephenzhangzsd@gmail.com> <244f1c7f-d6ca-bd7c-da5e-8da3bf8b5aee@redhat.com> <854ee6dc-2299-3897-c4af-3f7058f195af@redhat.com> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.38.1-1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2021-01-27 at 19:23 +0100, Paolo Bonzini wrote: > On 27/01/21 18:25, Joe Perches wrote: > > > > -#ifdef MMU_DEBUG > > -bool dbg = 0; > > -module_param(dbg, bool, 0644); > > -#endif > > - > >  #define PTE_PREFETCH_NUM 8 > >   > > > >  #define PT32_LEVEL_BITS 10 > > @@ -844,17 +839,17 @@ static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte, > >   int i, count = 0; > >   > > > >   if (!rmap_head->val) { > > - rmap_printk("pte_list_add: %p %llx 0->1\n", spte, *spte); > > + pr_debug("%p %llx 0->1\n", spte, *spte); > >   rmap_head->val = (unsigned long)spte; > >   } else if (!(rmap_head->val & 1)) { > > - rmap_printk("pte_list_add: %p %llx 1->many\n", spte, *spte); > > + pr_debug("%p %llx 1->many\n", spte, *spte); > >   desc = mmu_alloc_pte_list_desc(vcpu); > > This would be extremely slow. These messages are even too verbose for > tracepoints. There's no real object change. It's not enabled unless DEBUG is defined (and it's not enabled by default) or CONFIG_DYNAMIC_DEBUG is enabled and then dynamic_debug jump points are used when not enabled so I think any slowdown, even when dynamic_debug is enabled is trivial.