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=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 A259DC433E0 for ; Wed, 27 Jan 2021 05:36:35 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id ABEC020709 for ; Wed, 27 Jan 2021 05:36:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ABEC020709 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bugs.launchpad.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:34834 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l4dVJ-00014X-8o for qemu-devel@archiver.kernel.org; Wed, 27 Jan 2021 00:36:33 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:38168) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l4dUS-0000Ee-00 for qemu-devel@nongnu.org; Wed, 27 Jan 2021 00:35:40 -0500 Received: from indium.canonical.com ([91.189.90.7]:43912) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1l4dUP-0005om-KG for qemu-devel@nongnu.org; Wed, 27 Jan 2021 00:35:39 -0500 Received: from loganberry.canonical.com ([91.189.90.37]) by indium.canonical.com with esmtp (Exim 4.86_2 #2 (Debian)) id 1l4dUN-0004Uu-3M for ; Wed, 27 Jan 2021 05:35:35 +0000 Received: from loganberry.canonical.com (localhost [127.0.0.1]) by loganberry.canonical.com (Postfix) with ESMTP id 17A472E813C for ; Wed, 27 Jan 2021 05:35:35 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Wed, 27 Jan 2021 05:28:37 -0000 From: ANIMESH KUMAR SINHA <1912777@bugs.launchpad.net> To: qemu-devel@nongnu.org X-Launchpad-Notification-Type: bug X-Launchpad-Bug: product=qemu; status=Incomplete; importance=Undecided; assignee=None; X-Launchpad-Bug: distribution=ubuntu; sourcepackage=None; component=None; status=New; importance=Undecided; assignee=None; X-Launchpad-Bug-Information-Type: Public X-Launchpad-Bug-Private: no X-Launchpad-Bug-Security-Vulnerability: no X-Launchpad-Bug-Commenters: animeshk th-huth X-Launchpad-Bug-Reporter: ANIMESH KUMAR SINHA (animeshk) X-Launchpad-Bug-Modifier: ANIMESH KUMAR SINHA (animeshk) References: <161131847021.10154.14606822070729811950.malonedeb@gac.canonical.com> Message-Id: <161172531717.4863.12889942733969696473.malone@soybean.canonical.com> Subject: [Bug 1912777] Re: KVM_EXIT_MMIO has increased in Qemu4.0.0 when compared to Qemu 2.11.0 X-Launchpad-Message-Rationale: Subscriber (QEMU) @qemu-devel-ml X-Launchpad-Message-For: qemu-devel-ml Precedence: bulk X-Generated-By: Launchpad (canonical.com); Revision="e00fb96b2e64b75333d0178ec15cb78e5aadb64d"; Instance="production" X-Launchpad-Hash: 2163e45b183881e19e2602005622149ced8082c7 Received-SPF: none client-ip=91.189.90.7; envelope-from=bounces@canonical.com; helo=indium.canonical.com X-Spam_score_int: -65 X-Spam_score: -6.6 X-Spam_bar: ------ X-Spam_report: (-6.6 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.249, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Bug 1912777 <1912777@bugs.launchpad.net> Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" The testcase is a rather a very basic one. Doing a mmap on a pcie device and triggering a read and write operation on = the Virtual Address, which would in-turn trigger transaction requests on th= e host device. I understand that Qemu v4.0 may be and old one, but the issue is that test case execution has become rather very slow with Qemu4.0.0 and the only thing i could notice from using tracebacks were related with increase in KVM_MMIO_EXIT when compared with Qemu2.11.0 version. Can it be verified as to why the number of KVM_EXIT_MMIO has increased drastically in qemu4 when compared to Qemu2.11.0 ? -- = You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1912777 Title: KVM_EXIT_MMIO has increased in Qemu4.0.0 when compared to Qemu 2.11.0 Status in QEMU: Incomplete Status in Ubuntu: New Bug description: I was able to generate trace dump in Qemu for kvm_run_exit event in both = QEMU 2.11.0 and QEMU 4.0.0 From the trace i noticed that the number of KVM_KXIT_MMIO calls has incre= ased alot and is causing delay in testcase execution. I executed same testcase from Qemu 2.11 and Qemu4. Inside Virtual machine when using qemu 2.11 testcase got completed in 11 = seconds but the same testcase when executed on Qemu 4.0.0 got executed in 26 seco= nds. = I did a bit of digging and extracted the kvm_run_exit to figure out whats= going on. Please find = Stats from Qemu2.11: KVM_EXIT_UNKNOWN : 0 KVM_EXIT_EXCEPTION : 0 KVM_EXIT_IO : 182513 KVM_EXIT_HYPERCALL : 0 KVM_EXIT_DEBUG : 0 KVM_EXIT_HLT : 0 KVM_EXIT_MMIO : 216701 KVM_EXIT_IRQ_WINDOW_OPEN : 0 KVM_EXIT_SHUTDOWN : 0 KVM_EXIT_FAIL_ENTRY : 0 KVM_EXIT_INTR : 0 KVM_EXIT_SET_TPR : 0 KVM_EXIT_TPR_ACCESS : 0 KVM_EXIT_S390_SIEIC : 0 KVM_EXIT_S390_RESET : 0 KVM_EXIT_DCR : 0 KVM_EXIT_NMI : 0 KVM_EXIT_INTERNAL_ERROR : 0 KVM_EXIT_OSI : 0 KVM_EXIT_PAPR_HCALL : 0 KVM_EXIT_S390_UCONTROL : 0 KVM_EXIT_WATCHDOG : 0 KVM_EXIT_S390_TSCH : 0 KVM_EXIT_EPR : 0 KVM_EXIT_SYSTEM_EVENT : 0 KVM_EXIT_S390_STSI : 0 KVM_EXIT_IOAPIC_EOI : 0 KVM_EXIT_HYPERV : 0 KVM_RUN_EXIT : 399214 (Total in Qemu 2.11 for a testcase) = Stats For Qemu 4.0.0: VM_EXIT_UNKNOWN : 0 = = = KVM_EXIT_EXCEPTION : 0 = = = KVM_EXIT_IO : 163729 = = = KVM_EXIT_HYPERCALL : 0 = = = KVM_EXIT_DEBUG : 0 = = = KVM_EXIT_HLT : 0 = = = KVM_EXIT_MMIO : 1094231 = = = KVM_EXIT_IRQ_WINDOW_OPEN : 46 = = = KVM_EXIT_SHUTDOWN : 0 = = = KVM_EXIT_FAIL_ENTRY : 0 = = = KVM_EXIT_INTR : 0 = = = KVM_EXIT_SET_TPR : 0 = = = KVM_EXIT_TPR_ACCESS : 0 = = = KVM_EXIT_S390_SIEIC : 0 = = = KVM_EXIT_S390_RESET : 0 = = = KVM_EXIT_DCR : 0 = = = KVM_EXIT_NMI : 0 = = = KVM_EXIT_INTERNAL_ERROR : 0 = = = KVM_EXIT_OSI : 0 = = = KVM_EXIT_PAPR_HCALL : 0 = = = KVM_EXIT_S390_UCONTROL : 0 = = = KVM_EXIT_WATCHDOG : 0 = = = KVM_EXIT_S390_TSCH : 0 = = = KVM_EXIT_EPR : 0 = = = KVM_EXIT_SYSTEM_EVENT : 0 = = = KVM_EXIT_S390_STSI : 0 = = = KVM_EXIT_IOAPIC_EOI : 464 = = = KVM_EXIT_HYPERV : 0 = KVM_RUN_EXIT : 1258470 (Total in qemu 4.0.0 for same testcase) From above analysis i found that the number of KVM_EXIT_MMIO has increased by 4.x. Could someone from qemu community help me understand as to why the MMIO exits have increased in qemu4 ? The results i obtained are after running same testcase. On Qemu2.11 testcase gets completed in : 11seconds on Qemu4.11 testcase gets completed in : 26 seconds VM Qcow2 used in Ubuntu 16.04 VM kernel OS is : 4.4 generic = Let me know incase more information is required . To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1912777/+subscriptions