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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F7A1C433F5 for ; Sat, 12 Feb 2022 00:13:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354349AbiBLANv (ORCPT ); Fri, 11 Feb 2022 19:13:51 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:54036 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234135AbiBLANu (ORCPT ); Fri, 11 Feb 2022 19:13:50 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 72BCCD41 for ; Fri, 11 Feb 2022 16:13:47 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1140661B76 for ; Sat, 12 Feb 2022 00:13:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPS id 7B82FC340F3 for ; Sat, 12 Feb 2022 00:13:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644624826; bh=NxoOSaL/buRf39IPk7pivD5SRhjq+Qugu4td5l+HpzE=; h=From:To:Subject:Date:In-Reply-To:References:From; b=KfGub7iRk7cFROmhhATliFFpC/xK+PGuf2eaC3gIBVxKhgSp76g1/lxY9gCpN5ZGe k3SwjsV5zqjyFg4G6LbGNAGWMezHLLb5txoVYxIOVRGTKW2mA8/Zw+M3fPjfxMz6kX 5FoqBdTX8foZBG1TjW0jRp8kwCkBX5jYs2MSHRd4t1IMY+Q31FojVveN7EU0Q0koVZ BV5m1eveOehh3OkT37HW68wsR7wOzq9VYZfGgPlAbgfaX6qGkb1JXVB7K3NLKLeyT/ LLgSVMRlh9PQyLG/F8r8TdlXi07YEtxGO3R6LKC5aNNiAO8AkfLJUI2V6Cmp2zt+xw iIEdNubm1z1bQ== Received: by aws-us-west-2-korg-bugzilla-1.web.codeaurora.org (Postfix, from userid 48) id 62AF8CC13A6; Sat, 12 Feb 2022 00:13:46 +0000 (UTC) From: bugzilla-daemon@kernel.org To: kvm@vger.kernel.org Subject: [Bug 199727] CPU freezes in KVM guests during high IO load on host Date: Sat, 12 Feb 2022 00:13:46 +0000 X-Bugzilla-Reason: None X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: AssignedTo virtualization_kvm@kernel-bugs.osdl.org X-Bugzilla-Product: Virtualization X-Bugzilla-Component: kvm X-Bugzilla-Version: unspecified X-Bugzilla-Keywords: X-Bugzilla-Severity: high X-Bugzilla-Who: devzero@web.de X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P1 X-Bugzilla-Assigned-To: virtualization_kvm@kernel-bugs.osdl.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugzilla.kernel.org/ Auto-Submitted: auto-generated MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org https://bugzilla.kernel.org/show_bug.cgi?id=3D199727 --- Comment #8 from Roland Kletzing (devzero@web.de) --- yes. i found the following interesting information. i think this explains a LOT. https://docs.openeuler.org/en/docs/20.03_LTS/docs/Virtualization/best-pract= ices.html#i-o-thread-configuration I/O Thread Configuration Overview By default, QEMU main threads handle backend VM read and write operations on the KVM. This causes the following issues: VM I/O requests are processed by a QEMU main thread. Therefore, the single-thread CPU usage becomes the bottleneck of VM I/O performance. The QEMU global lock (qemu_global_mutex) is used when VM I/O requests a= re processed by the QEMU main thread. If the I/O processing takes a long time,= the QEMU main thread will occupy the global lock for a long time. As a result, = the VM vCPU cannot be scheduled properly, affecting the overall VM performance = and user experience. You can configure the I/O thread attribute for the virtio-blk disk or virtio-scsi controller. At the QEMU backend, an I/O thread is used to proce= ss read and write requests of a virtual disk. The mapping relationship between= the I/O thread and the virtio-blk disk or virtio-scsi controller can be a one-to-one relationship to minimize the impact on the QEMU main thread, enh= ance the overall I/O performance of the VM, and improve user experience. Configu --=20 You may reply to this email to add a comment. You are receiving this mail because: You are watching the assignee of the bug.=