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Thu, 28 May 2020 22:59:07 +0000 (UTC) Date: Thu, 28 May 2020 16:59:06 -0600 From: Alex Williamson To: "Dr. David Alan Gilbert" Subject: Re: [PATCH Kernel v22 0/8] Add UAPIs to support migration for VFIO devices Message-ID: <20200528165906.7d03f689@x1.home> In-Reply-To: <20200527084822.GC3001@work-vm> References: <1589781397-28368-1-git-send-email-kwankhede@nvidia.com> <20200519105804.02f3cae8@x1.home> <20200525065925.GA698@joy-OptiPlex-7040> <426a5314-6d67-7cbe-bad0-e32f11d304ea@nvidia.com> <20200526141939.2632f100@x1.home> <20200527062358.GD19560@joy-OptiPlex-7040> <20200527084822.GC3001@work-vm> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Received-SPF: pass client-ip=207.211.31.120; envelope-from=alex.williamson@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/28 17:46:56 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Zhengxiao.zx@alibaba-inc.com, kevin.tian@intel.com, yi.l.liu@intel.com, cjia@nvidia.com, kvm@vger.kernel.org, eskultet@redhat.com, ziye.yang@intel.com, cohuck@redhat.com, shuangtai.tst@alibaba-inc.com, qemu-devel@nongnu.org, zhi.a.wang@intel.com, mlevitsk@redhat.com, pasic@linux.ibm.com, aik@ozlabs.ru, Kirti Wankhede , eauger@redhat.com, felipe@nutanix.com, jonathan.davies@nutanix.com, Yan Zhao , changpeng.liu@intel.com, Ken.Xue@amd.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, 27 May 2020 09:48:22 +0100 "Dr. David Alan Gilbert" wrote: > * Yan Zhao (yan.y.zhao@intel.com) wrote: > > BTW, for viommu, the downtime data is as below. under the same network > > condition and guest memory size, and no running dirty data/memory produced > > by device. > > (1) viommu off > > single-round dirty query: downtime ~100ms > > Fine. > > > (2) viommu on > > single-round dirty query: downtime 58s > > Youch. Double Youch! But we believe this is because we're getting the dirty bitmap one IOMMU leaf page at a time, right? We've enable the kernel to get a dirty bitmap across multiple mappings, but QEMU isn't yet taking advantage of it. Do I have this correct? Thanks, Alex