Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752773AbbHFFia (ORCPT ); Thu, 6 Aug 2015 01:38:30 -0400 Received: from mga03.intel.com ([134.134.136.65]:53618 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750758AbbHFFi3 convert rfc822-to-8bit (ORCPT ); Thu, 6 Aug 2015 01:38:29 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,622,1432623600"; d="scan'208";a="536907945" From: "Li, Liang Z" To: Paolo Bonzini , "'Juan Quintela'" , "linux-kernel@vger.kernel.org" CC: "Zhang, Yang Z" , "kvm@vger.kernel.org" Subject: RE: about the time consuming kvm_vcpu_ioctl issue in rhel kernel Thread-Topic: about the time consuming kvm_vcpu_ioctl issue in rhel kernel Thread-Index: AdDP9UJwwpuw8Ol+QP2Z1DthOfo0awAE1k6w Date: Thu, 6 Aug 2015 05:38:23 +0000 Message-ID: Accept-Language: zh-CN, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1197 Lines: 28 The synchronize_rcu() is a time consuming operation, the unpstream kernel still have some issue, the KVM_RUN ioctl will take more then 10ms when resume the VM after migration. Liang > -----Original Message----- > From: Li, Liang Z > Sent: Thursday, August 06, 2015 11:47 AM > To: 'Paolo Bonzini'; 'Juan Quintela'; linux-kernel@vger.kernel.org > Cc: Zhang, Yang Z; kvm@vger.kernel.org > Subject: about the time consuming kvm_vcpu_ioctl issue in rhel kernel > > Hi Paolo & Juan, > > I found some of the kvm_vcpu_ioctl operation takes about more than 10ms > with the 3.10.0-229.el7.x86_64 kernel, which prolong the VM service > downtime when doing live migration about 20~30ms. > This happened when doing the KVM_KVMCLOCK_CTRL ioctl. It's worse if > more VCPUs used by guest(4VPUs in my test). The upstream kernel does not > have this issue because of the patch 7a72f7a140bfd3, maybe this patch > should be backported to the el7 kernel. > > Liang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/