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 96CF8C433EF for ; Wed, 2 Mar 2022 13:33:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242255AbiCBNec (ORCPT ); Wed, 2 Mar 2022 08:34:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51718 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240656AbiCBNeb (ORCPT ); Wed, 2 Mar 2022 08:34:31 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4574C5D5E6 for ; Wed, 2 Mar 2022 05:33:48 -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 ams.source.kernel.org (Postfix) with ESMTPS id F2B1BB81F1B for ; Wed, 2 Mar 2022 13:33:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPS id B9AB5C340F4 for ; Wed, 2 Mar 2022 13:33:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1646228025; bh=t4FFf16vq/qHGgAxTeFAj5ycJuoVKQXacxJzBiYbock=; h=From:To:Subject:Date:In-Reply-To:References:From; b=b/Xp4Z4+T9cKvsNXbHEsshxR2sJtuaQwiySHo4DZ92WohQc/RgeCgM08DdmxuYNSG ajwGEUSblXPdLKY1HqOm+pn4o0GySHExO1T10QAgQSvlOjVCeBHgd1wpXiFIH+7aZ7 Gbbv9GJUkDEu4cn/9lIcH+XsdxXSTts3qoRNlE0ph7D4kMSKss1PGKp1TuwPueS0nc GtfN92PUu0wuEIqC5laA0eulhFyLy7su3hEDHwZztAcwzW4RYSHDj2XXSEhlGsL7fR h31HjDibBgvNMIStjM263fX2URG+5pcLJuSfZSpGyEMLOiui0ACZZmDtXJyDOeRUgK IjG/ByWe9Gm3A== Received: by aws-us-west-2-korg-bugzilla-1.web.codeaurora.org (Postfix, from userid 48) id A7BC7C05FF5; Wed, 2 Mar 2022 13:33:45 +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: Wed, 02 Mar 2022 13:33:45 +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: stefanha@gmail.com 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: cc 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 Stefan Hajnoczi (stefanha@gmail.com) changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |stefanha@gmail.com --- Comment #12 from Stefan Hajnoczi (stefanha@gmail.com) --- Hi, I contribute to QEMU and have encountered similar issues in the past. QEMU configuration options that should allow you to avoid this issue and it soun= ds like you have found options that work for you. If io_submit(2) is blocking with aio=3Dnative, try aio=3Dio_uring. If that = is not available (older kernels), use aio=3Dthreads to work around this particular problem. I recommend cache=3Dnone. Although cache=3Dwriteback can shift the problem = around it doesn't solve it and leaves the VMs open to unpredictable performance (including I/O stalls like this) due to host memory pressure and host page cache I/O. Regarding the original bug report, it's a limitation of that particular QEMU configuration. I don't think anything will be done about it in the Linux kernel. Maybe Proxmox can adjust the QEMU configuration to avoid it. --=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.=