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Friday, October 30
 

06:00 GMT

Live Migration With Hardware Acceleration - Wei Wang, Intel
Guests with memory write intensive workloads are difficult to live migrate and guests with large memory size take long time to migrate. The existing solutions reduce the amount of data to migrate using extra CPU cycles to compress the memory or perform delta operations to migrate the updated bytes. Those do not work as fast as expected, and optimizations like multi-threading compression consume lots of host CPUs. This talk introduces some features enhanced to the migration framework to use hardware accelerators to process the guest memory. Initial results with QAT-based compression show ~5x larger migration throughput compared to compression using 16 CPUs, which consequently supports higher guest dirty rate and has shorter migration time. DSA-based delta operation is work in progress and it performs better when the delta encoding rate is higher than the compress rate.

Speakers
avatar for Wei Wang

Wei Wang

Senior Software Engineer, Intel Corp.
Wei is currently a software developer at Intel. He earned a Master degree from the University of Ottawa, Canada. Wei has rich experience in the virtualization field and he worked on many projects such as network virtualization, live migration, memory ballooning, PMU virtualization... Read More →



Friday October 30, 2020 06:00 - 06:30 GMT
KVM Theater
  KVM Track 1

06:00 GMT

Intel Virtualization Technology Extensions to Enable Hardware Isolated VMs - Sean Christopherson, Intel
Deploying virtual machines in an unsecured environment might expose a cloud tenant to risk of losing confidentiality and integrity of its sensitive data and IP, e.g. via attacks from privileged software, offline memory analysis, and active memory attacks at system interfaces. This talk will present an upcoming Intel technology to isolate VMs from many hardware and most software-based threats, by providing capabilities for confidentiality and integrity of memory, address translation, and cpu state, as well as secure interrupt and exception delivery, and remote attestation. Sean will provide an overview of the technology and its unique, novel features, and briefly cover the state of enabling in KVM and Qemu.

Speakers
avatar for Sean Christopherson

Sean Christopherson

Software Engineer, Intel
Sean is a reviewer for x86 KVM's VMX and MMU sub-sub-systems, and a prolific contributor to KVM. Sean is the lead KVM developer for SGX and TDX.



Friday October 30, 2020 06:00 - 06:30 GMT
KVM Theater
  KVM Track 2

06:30 GMT

Scalable Work Submission in Device Virtualization - Hao Wu, Intel
Hardware I/O virtualization techniques, such as PCIe SR-IOV and Intel Scalable IOV, allows devices to be shared by multiple clients (e.g. VMs) with minimal emulation cost. However, some devices may not allow fine-grained partitioning of its backend resources, thus imposing a scalability limitation. ENQCMD (Enqueue Command) is a new instruction on future Intel platforms to allow scalable work submission for such devices. The instruction payload includes the work descriptor and a unique PASID to identify the client who is submitting the work, thus allowing a single work queue to be shared between multiple clients. In this talk, Hao will introduce the ENQCMD concept and how to efficiently virtualize it through hardware/software extensions, based on the example implementation on Scalable IOV based device.

Speakers
HW

Hao Wu

Senior Software Engineer, Intel
Hao is from Intel Virtualization Enabling Team and now working on ENQCMD virtualization support and also other Scalable IOV related development. Hao joined Intel at 2009, besides virtualization, he also has a lot of experience on Linux Kernel and device drivers development.



Friday October 30, 2020 06:30 - 07:00 GMT
KVM Theater
  KVM Track 1

06:30 GMT

Guest Memory Protection -- Current Status and Future - Isaku Yamahata, Intel
Recently there are several proposals for protect guest memory from KVM as VMM and qemu as user space in various ways of software and hardware. We discuss the guest memory protection and how we can proceed those efforts. As software solution, the proposal of KVM protected memory extension, the mapping of guest memory is removed from kernel address space (direct mapping area) and make user space mapping as NONE permittion. Also the proposal of execute only memory(XOM) introduce a new software type of guest memory as execute only. Also removing mapping from use space is also important part of guest memory protection which may require changes intrusive to KVM MMU. Live migration also needs attention for guest protection because guest memory protection means that qemu can't directly access guest memory/status. After summarizing proposals, consider how we can proceed them.

Speakers
avatar for Isaku Yamahata

Isaku Yamahata

Software engineer, Intel
Isaku Yamahata is a Software architect in the Open Source Technology Center, Intel. His main focus is virtualization technology, network virtualization as Software Defined Networking for multiple years. Isaku is an active on Graphene LibOS and OpenStack Neutron (networking) and has... Read More →


Friday October 30, 2020 06:30 - 07:00 GMT
KVM Theater
  KVM Track 2

07:00 GMT

PASID Management in KVM - Yi Liu& Jacob Pan, Intel
PASID (Process Address Space ID) is a PCIe capability that enables sharing of a single device across multiple isolated address domains. It has been becoming a hot topic in I/O technology evolution. e.g. as the foundation of SVA (Shared Virtual Addressing) and SIOV (Scalable I/O Virtualization). Although PASID itself is a generic concept, different usages/requirements are imposed cross vendors thus bringing an interesting challenge to PASID management in Linux. This talk will first review the PASID usages, introduce the IOASID (I/O Address Space ID) core logic in Linux, and then elaborate the gaps/solutions for efficient PASID management in KVM/VFIO.

Speakers
avatar for Jacob Pan

Jacob Pan

Linux Kernel Developer, Intel Corporation
Jacob is a veteran Linux kernel developer at Intel. His most recent interest and work are on Shared Virtual Address/Memory as well as the IOMMU subsystem in general.Prior to that, Jacob contributed to power management, device drivers, interrupt, timers, and X86 core.
avatar for Yi Liu

Yi Liu

Software Engineer, Intel Corporation
Yi is a software engineer from Intel Virtualization team, focusing on I/O virtualization technology. He works on Shared Virtual Memory, Scalable IOV and vIOMMU stuffs in recent years. He has been invited to give presentation at LPC 2017, LinuxCon Beijing 2018 and KVM Forum 2018, Intel... Read More →



Friday October 30, 2020 07:00 - 07:30 GMT
KVM Theater
  KVM Track 1

07:00 GMT

KVM Live Upgrade with Properly Handling of Passthrough Devices - Zhimin Feng, ByteDance
VMM live upgrade is an emerging approach to upgrade the VMM without the host shutdown. There are several implementations of live upgrade for KVM. However, none of them seems handling the passthrough devices flawlessly. In this talk, we will analyze the requirements for the passthrough devices handling, and present how we follow those requirements to properly handle passthrough devices in our KVM live upgrade implementation. In addition, we also optimize the startup and suspend of VM, Our experiment shows that the total downtime is 13ms for VMM live upgrade(VM has 8 virtual CPUSs, 8GB memory, 1 disk and 1 network card.)

Speakers
ZF

Zhimin Feng

Software Engineer, ByteDance
I am now working for ByteDance., currently focusing on QEMU/Virtualization related projects.


Friday October 30, 2020 07:00 - 07:30 GMT
KVM Theater
  KVM Track 2
  • Technical Skill Level Any

07:30 GMT

Building a Cloud Infrastructure to Deploy Microservices as Microvm Guests - Matias Vara Larsen, Huawei
This talk presents a proof of concept solution that evaluates a cloud infrastructure to deploy microservices by relying on microvm Qemu machine, virtio-fs and virtio-vsocket. Microservices run as Toro's guest, a dedicated unikernel to deploy all-in-one embedded applications into the cloud. We highlight the following benefits when using microvm machine, virtio-fs and virtio-vsocket: reduced attack surface, deployment of several VMs in a single host, continuous deployment due to the short booting time, easily VMs configuration and simplified unikernel architecture. The infrastructure is built on top of a CephFS cluster thus allowing VMs to share a common filesystem. During the talk, we present the architecture of such a cloud infrastructure and the current implementation. We discuss technical challenges and ongoing work. The tutorial and scripts to reproduce this infrastructure can be found at https://github.com/torokernel/torocloudscripts.

Speakers
avatar for Matias Vara Larsen

Matias Vara Larsen

Software Engineer, Huawei
I am a Software Engineer at Huawei. I am interested in the use of formal languages and the development of Operating Systems.



Friday October 30, 2020 07:30 - 08:00 GMT
KVM Theater
  KVM Track 1

07:30 GMT

Device Keepalive State for Local Live Migration and VMM Fast Restart - Jason Zeng, Intel
Passthrough devices are painpoints of VM live migration or VMM/Host upgrade. Currently there are community discussions and approaches to support passthrough device live migration, however they usually require vendor specific driver support, which is also a painpoint for legacy devices. This topic will introduce a new device state, keepalive state, for passthrough devices and other related hardware and software components to support local migration and VMM/host reboot. The new keepalive state doesn’t require vendor specific driver support for most legacy devices. It keeps devices and other related hardware alive during the local live migration period. In this topic, we will present the design and implementation of the kernel and Qemu changes for supporting keepalive state.

Speakers
JZ

Jason Zeng

Software Engineer, Intel Coporation
Jason Zeng is a software engineer from Intel virtualization team, focusing on various KVM/virtualization features and projects. Currently he is working on VMM Fast Restart project which aims to provide a solution for fast upgrading and rebooting VMM/host kernel while impose less impact... Read More →



Friday October 30, 2020 07:30 - 08:00 GMT
KVM Theater
  KVM Track 2

08:00 GMT

Coffee Break
Friday October 30, 2020 08:00 - 10:00 GMT
Sponsor Showcase

10:00 GMT

Evolution of SPDK vhost Towards Secure Container Storage Service - Xiaodong Liu & Changpeng LIu, Intel
Secure container provides strong isolation for multi-tenant, serverless workloads. Generally, it is light VM based, like Kata containers and Firecracker. It is already used in production by top CSPs. Previously, SPDK vhost application has been widely adopted for storage virtualization. While SPDK applications are polling based, and require hugepage memory. But for container scenarios, host resources are always oversubscribed in order to serve thousands of light VMs. This means reserved hugepage and polling pinned CPU cores are hard to be tolerated. So SPDK vhost should keep evolving to fit the requirement from container scenarios. In this talk, we will go over what evolution SPDK vhost requires and how polling pinned CPU and hugepage are avoided. With the new improvement, SPDK vhost will be a good choice to provide storage service to secure containers.

Speakers
CL

Changpeng Liu

Senior Software Engineer, Intel
Changpeng Liu is a senior software engineer in Intel and a core maintainer of SPDK (storage performance development kit) project. His working areas include NVMe, NVMf, virtualization and block storage.
avatar for Xiaodong Liu

Xiaodong Liu

Senior Cloud Engineer, Intel
Xiaodong Liu is a senior cloud engineer at Intel, working on storage related areas like Storage Performance Development Kit (SPDK) and Intel Intelligent acceleration Library (ISA-L). He focuses on acceleration, protocols and innovations among virtualization, cloud native storage and... Read More →


Friday October 30, 2020 10:00 - 10:30 GMT
KVM Theater
  KVM Track 1

10:00 GMT

Hypervisor-managed Linear Address Translation - Chao Gao, Intel
Some security features (e.g. write-protect kernel code, SMEP) are deployed in kernel to raise the bar of vulnerability exploitation. In practice, attackers would defeat or turn off these security features first. A typical way is by breaking code/data integrity of security features through editing page tables. In this case, enforcing linear translation is important to prevent security features being bypassed. But existing approaches to enforce guest linear translation generally lead to much overhead as guest page table changes and CR3 loading must be trapped by VMM. With HLAT enabled, VMM don’t need to monitor guest CR3 page table changes, thus reduces most overhead and improve efficiency. This presentation will first introduce the hardware extensions in HLAT, and then discuss how to build an efficient solution in KVM to enforce guest linear translation.

Speakers
CG

Chao Gao

Cloud Software Engineer, Intel
Chao has work for Intel for 4 years as a software engineer. He is responsible for enabling new Intel virtualization features in KVM/Xen and is familiar with interrupt virtualization, performance tuning and virtualization base security. Currently, Chao is working on using HLAT to enhance... Read More →



Friday October 30, 2020 10:00 - 10:30 GMT
KVM Theater
  KVM Track 2

10:30 GMT

Debugging KVM Using Intel DCI Technology - Raymond Zhang, Xedge.AI
Debugging KVM using print/log is inefficient and has many limitations. This talk will introduce a new way to debug KVM using the Direct Connect Interface (DCI). DCI is a new technology introduced by Intel Skylake. It exposes the Intel Target Probe (ITP) and JTAG scan chain to USB 3 ports so that host computer can build a JTAG connection with Intel silicon via a USB 3 cable. For the transportation lay is USB 3, it's very fast. Besides the transferring speed, debugging via DCI controls CPU at hardware level, has no dependency on software. This brings several benefits, such as break in when interrupt is off, break on VM entry and VM exit and single stepping sensitive code in VMM etc. In this talk, Raymond, a veteran Intel architect, will explain the DCI technology and how to use it to debug KVM, both the VMM layer and VM layer.

Speakers
RZ

Raymond Zhang

Software Architect, Xedge.AI
Raymond (Yinkui Zhang) is a widely recognized expert on system software and low level debugging. He is author of the top-selling book on Software Debugging and columnist for the Debugging Sword column of the Programmer magazine. He has worked in the IT industry for over 20 years with... Read More →


Friday October 30, 2020 10:30 - 11:00 GMT
KVM Theater
  KVM Track 1

10:30 GMT

Minimizing VMExits in Private Cloud by Aggressive PV IPI and Passthrough Timer - Qiao Hua & Zhou Yibo, ByteDance
VMExits caused by guest accesses to IPIs and timers have been observed as two of major overheads in virtualization. Lots of efforts have been taken in the community to reduce them. Most of them are designed for the public cloud scenarios and must follow the assertion that everything in VMs is untrusted. However, such assertion can be loosen in the private cloud scenarios where VMs can be partially trusted. Therefore, more aggressive optimization can be applied. In this talk, we will introduce our optimizations on guest IPIs and timers for KVM VMs in a private cloud. The optimizations are composed of an aggressive PV IPIs and a passthrough timer, which can eliminate most VMExits on both the setup and the interrupt injection paths. According to our early evaluation in a production environment, above optimizations can bring near bare-metal performance for certain guest workloads.

Speakers
QH

Qiao Hua

Software Engineer, Bytedance
ZY

Zhou Yibo

Engineer, Bytedance
zhou yibo is from bytedance, focus on the linux and Virtualization.


Friday October 30, 2020 10:30 - 11:00 GMT
KVM Theater
  KVM Track 2
  • Technical Skill Level Any

11:00 GMT

11:00 GMT

Coffee Break
Friday October 30, 2020 11:00 - 14:00 GMT
Sponsor Showcase

14:00 GMT

Speeding Up VM’s I/O Sharing Host's io_uring Queues With Guests - Stefano Garzarella, Red Hat
io_uring is the newest Linux I/O interface. It provides submission and completion queues for performing asynchronous I/O operations.

The queues are located in a memory region shared between the userspace application and the kernel. This aims to reduce the number of syscalls required for I/O operations and provides a way to poll efficiently. io_uring achieves good performance and it makes exposing submission and completion queues to guests an attractive idea for improving I/O performance in virtualization.

Stefano will give a brief overview of io_uring API. Then, he will illustrate how the host's io_uring queues can be shared with guests to improve I/O performance of a block device and which io_uring changes are required to safely give queues access to the guest. Finally, Stefano will show the performance boost achieved with the proposed approach and future steps.

Speakers
avatar for Stefano Garzarella

Stefano Garzarella

Senior Software Engineer, Red Hat
Stefano is a Senior Software Engineer at Red Hat. He is working on virtualization and networking topics in QEMU and Linux kernel. He is a co-maintainer of Linux's virtio-vsock. Current projects cover virtio-vsock, QEMU network and storage, and lightweight VMs.



Friday October 30, 2020 14:00 - 14:30 GMT
KVM Theater
  KVM Track 1

14:00 GMT

QEMU Live Update - Steven J. Sistare, Oracle
The ability to update software with critical bug fixes and security mitigations while minimizing downtime is valued highly by customers and providers. In this talk, Steve presents a new method for updating a running instance of QEMU to a new version while minimizing the impact on the VM guest. The guest pauses briefly, for less than 100 msec in the prototype, without loss of internal state or external connections. The old QEMU process exec's the new QEMU binary, and preserves anonymous guest RAM at the same virtual address via a proposed Linux madvise variant. Descriptors for external connections are preserved, and VFIO pass through devices are supported by preserving the VFIO device descriptors and attaching them to a new KVM instance after exec. The update method requires code changes to QEMU, but no changes are required in system libraries or the KVM kernel module.

Speakers
SS

Steven Sistare

Software Architect, Oracle Corporation
Steve is a software architect for the Oracle Linux kernel team, with particular interests in virtualization, performance, scalability, virtual memory, scheduling, security, tools, boot time, and processor support. He previously did similar work in the Solaris kernel. Steve graduated... Read More →



Friday October 30, 2020 14:00 - 14:30 GMT
KVM Theater
  KVM Track 2

14:30 GMT

Virtio-(balloon|pmem|mem): Managing Guest Memory - David Hildenbrand & Michael S. Tsirkin, Red Hat
How to resize guest memory? Can we reduce host swapping? Can we shrink the guest page cache? Traditional ballooning has been the answer to these questions for more than a decade - with advantages but also well-known issues. There is ongoing work to answer these questions in a better way, slowly but steadily obsoleting the original basis of virtio-balloon: the balloon. In addition to recent virtio-balloon extensions (e.g., free page hinting), new approaches, like virtio-pmem and virtio-mem, can substitute or replace ballooning. However, supporting technologies that mess with guest memory in the hypervisor (e.g., vfio, encrypted VMs), and closed-source guest operating systems become more challenging. In this talk, we give an overview of the current state of virtio-balloon, virtio-pmem and virtio-mem, discussing advantages, issues, and open items of each, and draw a picture of the future.

Speakers
avatar for David Hildenbrand

David Hildenbrand

Senior Software Engineer, Red Hat
David has been working on QEMU/KVM for almost 6 years now. His current projects are mostly centered around memory hot(un)plug and memory overcommit in the context of virtual machines. While he's involved with QEMU/KVM on s390x and Linux memory management in general, his main projects... Read More →
MS

Michael S. Tsirkin

Distinguished Engineer, Red Hat Inc
Michael has been with Red Hat for more than 10 years. In his role as a Distinguished Engineer he acts as a chair of the Virtio Technical Committee, overseeing the development of the virtio specification for virtual devices. He also maintains several subsystems in QEMU and Linux and... Read More →



Friday October 30, 2020 14:30 - 15:00 GMT
KVM Theater
  KVM Track 1

14:30 GMT

Faster and Smaller qcow2 Files With Subcluster-based Allocation - Alberto Garcia, Igalia
qcow2 is QEMU's native format for disk images. qcow2 images are smaller and more flexible than raw files but are also slower. This problem can be partially mitigated by adjusting the cluster size when creating a new qcow2 image. However there is always a trade-off that needs to be considered: smaller cluster sizes result in smaller images and generally faster allocations but also in more metadata and larger memory requirements. Several approaches have been followed in order to improve this situation. In this presentation we introduce subcluster allocation: a new extension for the qcow2 file format that tries to combine the best of both worlds, producing images that are both faster and smaller.

Speakers
AG

Alberto Garcia

Software Engineer, Igalia
Alberto Garcia is a software engineer working at Igalia. He has two decades of professional experience working with Linux-based systems and has been contributing to the QEMU project for more than five. In addition to that he was also involved in the development of the Maemo and MeeGo... Read More →


Friday October 30, 2020 14:30 - 15:00 GMT
KVM Theater
  KVM Track 2

15:00 GMT

Comparing Performance of NVMe Hard Drives in KVM, Baremetal, and Docker Using Fio and SPDK for Virtual Testbed Applications - Mauricio Tavares, RENCI
As it is known, the highest performance using a NVMe hard drive in a KVM guest is achievable using vfio-pci passthrough. Docker also allows PCI devices to be passed through. A lot of work has been done comparing some combination of drives in some combination of those platforms using some industry standard methods and parameters. But, how do they scale up when we want to add multiple drives per guest/container vs multiple guests/containers with one drive each? How about fine tuning memory/numa/iommu as we might also be passing out other CPI devices? And, and we want to build, test, and collect data in a reproducible way? Some ansible and shell scripting involved.

Speakers
MT

Mauricio Tavares

Creator of shiny thingies, RENCI
Mauricio Tavares (BS Aerospace Engineering) has worked with small and large companies in education, finance, and medical fields building and protecting user data. Currently a researcher at RENCI involved in next generation network research and an instructor with the Chameleon experimental... Read More →


Friday October 30, 2020 15:00 - 15:30 GMT
KVM Theater
  KVM Track 1
  • Technical Skill Level Any

15:00 GMT

QEMU Snaphosts Are So Slow. Really? - Denis Lunev, Virtuozzo
QEMU snapshots made via savevm interface are at the moment synchronous and slow. This happens not only due to not optimal code but also due to a gap between migration and block layer concepts. This presentation tries to cover this gap and provides some approaches to faster make snapshot and revert to snapshot operations. The talk will cover optimizations to the currently available synchronous SaveVM interface and will also cover asynchronous operations, including asynchronous revert to snapshot, which would require developing a memory page index for migration stream.

Speakers
DL

Denis Lunev

Team Lead, Virtuozzo
Denis Lunev is working in Virtuozzo around 20 years dealing with various aspects of virtualization, both in virtual machines and container worlds. Right now is working QEMU optimizations.



Friday October 30, 2020 15:00 - 15:30 GMT
KVM Theater
  KVM Track 2

15:30 GMT

Towards an Alternative Memory Architecture - Joao Martins, Oracle
We waste a lot of memory managing guest memory (ironic eh?). And in today's cloud ecosystem PCI passthrough is important and an increasing commodity. This gives us an opportunity to make a mean and lean hypervisor which can shed some of its layers. This talk discusses memory efficiency, particularly focusing on one of its oldest overheads: per page metadata. Particularly on what it means to strip that away, what it entails for security and performance, and how the DAX subsystem can be improved to fill in the gap, drawing KVM closer to that of a partitioned hypervisor.

Speakers
JM

João Martins

Snr Principal Software Engineer, Oracle
João is a Snr Principal Software Engineer working in the Oracle Linux Virtualization group. His work includes both Xen and more recently KVM, usually digging in networking performance and the hypervisor. Prior to Oracle, he did research on specialized OSes in the context of network... Read More →


Friday October 30, 2020 15:30 - 16:00 GMT
KVM Theater
  KVM Track 1

15:30 GMT

Bitmaps and NBD: Building Blocks of Change Block Tracking - Eric Blake, Red Hat
The premise of incremental backups is simple: if you can keep track of what changed, you can optimize a backup to visit only those portions of a disk image. But under the hood, there are a lot of moving parts that have been added and refined in the past few years to make incremental backups a reality when using qcow2 images. In this talk, Eric Blake will explore recent work in qemu to make bitmap tracking more powerful, enabling libvirt to finally add support for incremental backups even when a disk image is split across a backing chain involving multiple qcow2 files. Whether deciding which bitmaps should be active, or accessing the contents of those bitmaps over Network Block Device (NBD) for consumption by an arbitrary client, having an understanding of change block tracking and related technology can help you get the most performance from your incremental backups.

Speakers
avatar for Eric Blake

Eric Blake

Software Engineer, Red Hat
Eric Blake is a software engineer at Red Hat, working on block device management in virtualization. He has contributed extensively to qemu and libvirt. He has spoken at several past KVM Forums, most recently about making the most of NBD in Oct 2019.


Friday October 30, 2020 15:30 - 16:00 GMT
KVM Theater
  KVM Track 2

16:00 GMT

KVM Dirty Ring - A New Approach to Logging - Peter Xu, Red Hat
In this talk, Peter will present a new kvm dirty logging interface which is called kvm dirty ring. This is a carry-over work from Lei Cao and Paolo Bonzini which started a few years ago. Instead of using dirty bitmaps to record dirty pages, kvm dirty ring records the dirty pages in the form of an array of guest PFNs, which are recorded in per-vcpu ring structures. The memory consumption of dirty logging itself will be heavily reduced, and the size of the dirty rings will be configurable (via QEMU command lines). More importantly, dirty ring gives us a chance to be able to collect and sync dirty pages in a totally different way that will be extremely friendly to COLO-like applications. However, kvm dirty ring is not a super weapon to cover every single scenario. Peter will also talk about different user scenarios and on how to choose the correct logging method.

Speakers
avatar for Peter Xu

Peter Xu

Senior Software Engineer, Red Hat
Working for virtualization team of Red Hat. Presented talks in previous KVM forums related to vIOMMUs, vhost and device assignments.



Friday October 30, 2020 16:00 - 16:30 GMT
KVM Theater
  KVM Track 1

16:00 GMT

Bring SCSI Support Into QEMU Block Layer - Yaowei Bai, Chinamobile
Currently some storage technologies like Ceph already have the support of several SCSI interfaces like WRITE SAME and COMPARE AND WRITE, which can be called by QEMU block driver directly. However, QEMU still emulates them at the moment. We work on this by introducing SCSI support into QEMU block layer. This presentation will explain how this support is implemented and the problem it still has.

Speakers
YB

Yaowei Bai

Software engineer, Chinamobile
I'm a cloud software engineer focusing on virtualization and linux kernel in Chinamobile. Currently i'm working on high-performance distributed storage system basing on Ceph and spoke on Cephalocon 2020.


Friday October 30, 2020 16:00 - 16:30 GMT
KVM Theater
  KVM Track 2
  • Technical Skill Level Any

16:30 GMT

Long Live Asynchronous Page Fault! - Vitaly Kuznetsov & Vivek Goyal, Red Hat
Asynchronous Page Fault mechanism for KVM guests is not new, it's been around for more than a decade. Recently virtio-fs developers made an attempt to add new features to it and his attracted the attention of kernel developers to the internals. Some flaws in the original design of asynchronous page fault on x86 architecture were revealed, these flaws currently block addition of the new features. There is, however, an ongoing work aimed at fixing these issues. In this talk we'll try to cover asynchronous page fault mechanism: what is it needed for and how it works, both in 'normal' and 'nested' virtualization scenarios. We'll explain what potential issues were recently revealed and how we're fixing them. We'll describe new use-cases and features, both in-development and waiting to be implemented.

Speakers
avatar for Vitaly Kuznetsov

Vitaly Kuznetsov

Principal Software Engineer, Red Hat
Vitaly works at Virtualization Engineering team at Red Hat focusing on KVM development as well as making Linux the best guest for other hypervisors. He frequently presents at FOSDEM, KVM Forum, DevConf and other technical conferences.
VG

Vivek Goyal

Senior Principal Software Engineer, Red Hat
Vivek is a member of kernel storage team at Red Hat and has worked in various areas like Virtio FS, overlayfs SELinux support, docker storage, block cgroup controller, IO scheduler, kexec/kdump and secureboot. He frequently presents at LSF/MM, Linux plumbers and other technical c... Read More →



Friday October 30, 2020 16:30 - 17:00 GMT
KVM Theater
  KVM Track 1