Virtual Asymmetric Multiprocessor for Interactive Performance of Consolidated Desktops

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Virtual Asymmetric Multiprocessor for Interactive Performance of Consolidated Desktops Hwanju Kim 12, Sangwook Kim 1, Jinkyu Jeong 1, and Joonwon Lee 1 Sungkyunkwan

1 Virtual Asymmetric Multiprocessor for Interactive Performance of Consolidated Desktops Hwanju Kim 12, Sangwook Kim 1, Jinkyu Jeong 1, and Joonwon Lee 1 Sungkyunkwan University 1 University of Cambridge 2 The 10 th ACM SIGPLAN/SIGOPS International Conference on Virtual Execution Environments (VEE) Salt Lake City, Utah, March

2 Virtual Desktop Infrastructure (VDI) Desktop provisioning Dedicated workstations VM-based shared environments VM VM VM VM VM - Resource underutilization - High management cost - High maintenance cost - Energy wastage by idle desktops - Low level of security + High resource utilization + Low management cost (flexible HW/SW provisioning) + Low maintenance cost (dynamic HW/SW upgrade) + Energy savings by consolidation + High level of security (centralized data containment) 2/20

Desktop Consolidation Distinctive workload

4:1~15:1 [VMware VDI], 6~8 per core [Botelho

(multi-core) Multi-layer mixed workloads

consolidated VM Interactive Mixed VM VM VM

virtualization solution. (http://www.vmware.

3 Desktop Consolidation Distinctive workload characteristics High consolidation ratio 4:1~15:1 [VMware VDI], 6~8 per core [Botelho 08] Ever-increasing h/w parallelism (multi-core) Multi-layer mixed workloads Diverse user-dependent workloads 8 threads (Core i7) 16 threads (Nehalem EX) Multi-tasking (interactive+background) in a consolidated VM Interactive Mixed VM VM VM VM CPU-intensive VM VM VM VM VM Virtual Machine Monitor (VMM) Hardware Parallel [VMware VDI] Enabling your end-to end virtualization solution. ( [Botelho 08] Virtual machines per server, a viable metric for hardware selection? ( 3/20

4 Motivation Limited support for interactive performance Existing VMM schedulers give an illusion of symmetric multiprocessor (SMP) to each VM Proportional share-based scheduler used for commodity VMM (e.g., Xen, KVM, VMware) The size of = The amount of CPU shares Virtual SMP (vsmp) Virtual AMP (vamp) Equally contended regardless of user interactions Interactive VM Background Proposal Interactive VM Background Time shared Fast s Slow s pcpu pcpu pcpu pcpu pcpu pcpu pcpu pcpu 4/20

asymmetrically to sibling s within per- VM share budget for performance isolation Optional guest OS

5 Goal Issue Accurately identifying a set of interactive s Design goals VMM-level approach Identifying interactive s unobtrusively using simple VMM extension No share exchange Distributing CPU shares asymmetrically to sibling s within per- VM share budget for performance isolation Optional guest OS extension Optionally installing lightweight guest OS extension for further improvement of interactive performance 5/20

6 Workload Classification Previous methods Time-quanta based classification [Kim et al., VEE 09] Interactive workloads typically show short time quantum + Clear classification between I/O-bound and CPU-bound tasks - Modern interactive workloads show mixed behaviors - Multithreaded CPU-bound job shows short time quanta due to inter-thread communication [Kim et al., VEE 09] Task-aware virtual machine scheduling for I/O performance 6/20

7 Workload Classification Previous methods OS technique User I/O-driven IPC tracking [Zheng et al., SIGMETRICS 10] X server Terminal Firefox IPC IPC User I/O An interactive task group + Identifying a set of tasks involved in a user interaction (I/O) - Relying on various OS-level IPC structures E.g., socket, pipe, signal [Zheng et al., SIGMETRICS 10] RSIO: automatic user interaction detection and scheduling 7/20

Workload Classification Challenges Time-quanta based scheme cannot accurately classify modern desktop workloads VMM cannot access OS-internal IPC structure Key idea Tracking

8 Workload Classification Challenges Time-quanta based scheme cannot accurately classify modern desktop workloads VMM cannot access OS-internal IPC structure Key idea Tracking background tasks Identifying background CPU load before user I/O Interactive CPU load is typically initiated by user I/O VMM can unobtrusively monitor user I/O & per-task CPU load 8/20

Workload Classification Proposed scheme VM Background Interactive QEMU / SPICE Task Load Monitor User input T1 CPU CPU CPU CPU Interactive phase 3 4 1 2 T2 vamp Scheduler Task Load Monitor Background

9 Workload Classification Proposed scheme VM Background Interactive QEMU / SPICE Task Load Monitor User input T1 CPU CPU CPU CPU Interactive phase T2 vamp Scheduler Task Load Monitor Background task information KVM Hypervisor T1 T2 Background Background Time User I/O monitoring => I/O virtualization Per-task CPU load monitoring => task tracking technique [Jones et al., USENIX 06] [Jones et al., USENIX 06] Antfarm: Tracking processes in a virtual machine environment 9/20

10 Virtual Asymmetric Multiprocessor vamp Dynamically adjusting CPU shares of a according to its currently hosting task 1. Maintaining per-task CPU load during pre-i/o period Pre-I/O period is set to shorter than general user think time (1 second by default) 2. Tagging tasks that have generated nontrivial CPU loads as background tasks Threshold can be set to filter daemon tasks that possibly serve interactive workloads 3. Dynamically adjusting s shares based on weight ratio (e.g., background : non-background = 1:5) 4. Providing vamp during an interactive episode An interactive episode is restarted when another user I/O occurs or is finished if maximum time is elapsed without user I/O 10/20

11 Multimedia Workload Filtering Exceptional case Multimedia workloads (e.g., video playback) Can be misidentified as background workloads since it continuously generate CPU load without user input Key observation Multimedia workloads generally accompany audio output [Zheng et al., SIGMETRICS 10, Kim et al., MMSys 12] Solution Tracking tasks that access a virtual audio device Excluding audio access in an interrupt context Checking audio Interrupt Service Register (ISR) [Zheng et al., SIGMETRICS 10] RSIO: automatic user interaction detection and scheduling [Kim et al., MMSys 12] Scheduler support for video-oriented multimedia on client-side virtualization 11/20

12 Limitation An intrinsic limitation of VMM-only approach A vamp-oblivious OS scheduler Agnostic about underlying vamp (i.e., all s are identical) Possibly multiplexing interactive and background tasks on the same A slow has higher scheduling latency Frequent multiplexing might offset the benefit of vamp Example: A scheduling trace during Google Chrome launch Background task Non-background task vamp might less effective if multiplexing frequently happens Guest OS can be enlightened to mitigate the adverse effect of multiplexing 12/20

13 Guest OS Extension Guest OS extension for vamp OS enlightenment about vamp To avoid ineffective multiplexing of interactive and background tasks on the same Isolation Design principles Keeping VMM OS-independent Optional extension for further enhancement of interactive performance Keeping extension OS-independent No reliance on specific OS functionality Isolating tasks on separate CPUs is a general interface of commodity OSes (e.g., modifying CPU affinity) Small kernel changes for low maintenance cost 13/20

Guest OS Extension Linux extension for vamp User-level vamp-daemon Isolating background tasks exposed by VMM from nonbackground tasks Small

Initially dedicating nr_fast_vcpus to interactive tasks (i.e., non-background tasks) Input interface Procfs interface T 3 T 4 Cpuset interface Kernel T 1 T 2 2.

isolation) Background tasks T 1, T 2 Task load monitor vamp scheduler VMM [Blake et al.

14 Guest OS Extension Linux extension for vamp User-level vamp-daemon Isolating background tasks exposed by VMM from nonbackground tasks Small kernel changes that expose background tasks to user VM 1. Eventdriven vamp-daemon 2. Read 3. Isolate User Isolation procedure: 1. Initially dedicating nr_fast_vcpus to interactive tasks (i.e., non-background tasks) Input interface Procfs interface T 3 T 4 Cpuset interface Kernel T 1 T 2 2. Periodically increasing nr_fast_vcpus when fast s become fully utilized (also periodically checking the end of an interactive episode stop isolation) Background tasks T 1, T 2 Task load monitor vamp scheduler VMM [Blake et al., ISCA 10] Evolution of thread-level parallelism in desktop applications Default nr_fast_vcpus = 1 due to the low thread-level parallelism of interactive workloads [Blake et al., ISCA 10] 14/20

15 Experimental Setup S/W Linux KVM QEMU 1.0: handles I/O requests from guest OS H/W Intel Xeon X Ghz quad-core processor 8 pcpus are available w/ hyperthreading enabled 8GB of DDR3 DRAM Measurement methodology Spiceplay: measures client-side performance Snapshot-based record/replay Robust replay for varying loads Similar to VNCPlay [Zeldovich et al., USENIX 05] and Deskbench [Rhee et al., IM 09] Extension on the SPICE remote desktop client [Zeldovich et al., USENIX 05] Interactive performance measurement with VNCplay [Rhee et al., IM 09] DeskBench: Flexible virtual desktop benchmarking toolkit 15/20

Normalized average launch time Evaluation Application launch Background workload Remote desktop client App launch Data mining application (freqmine) with 8 threads Weight ratio (background :

16 Normalized average launch time Evaluation Application launch Background workload Remote desktop client App launch Data mining application (freqmine) with 8 threads Weight ratio (background : non-background) vamp(l)=1:3, vamp(m)=1:9, vamp(h)=1:18 8- VM freqmine 8-pCPU 8- VM freqmine vamp improves launch performance by 7~40% High weight ratio is ineffective because of negative effect of multiplexing 0.80 Baseline vamp(l) Why did Gimp show significant improvement even without the guest OS extension? 0.60 vamp(m) 0.40 vamp(h) 0.20 vamp(l) w/ Ext vamp(m) w/ Ext 0.00 Impress Firefox Chrome Gimp vamp(h) w/ Ext Interactive applications Guest OS extension achieves further improvement of interactive performance by up to 70% 16/20

17 Evaluation Application launch Chrome vs. Gimp (without guest OS extension) Chrome (Web browser) Background task Non-background task Many threads are cooperatively scheduled in a fine-grained manner Gimp (Image editing program) Background task Non-background task A single thread dominantly involves computation with little communication 17/20

Average frames per second (FPS) Evaluation Media player VLC media player 1920x800 HD video with 23.

18 Average frames per second (FPS) Evaluation Media player VLC media player 1920x800 HD video with frames per second (FPS) Mult: multimedia workload filtering Media player 8- VM freqmine 8-pCPU 8- VM freqmine Without multimedia workload filtering, 30 VLC is misidentified as a background task vamp improves playback quality by up to 22.3 FPS, but high weight ratio still degrades the quality Baseline vamp(l) w/o Mult vamp(l) vamp(m) vamp(h) vamp(l) w/ Ext vamp(m) w/ Ext vamp(h) w/ Ext 0 Guest OS extension achieves 23.8 FPS 18/20

19 Conclusion vamp Dynamically varying performance based on their hosting workloads A feasible method of improving interactive performance Assisted by a simple guest OS extension Isolation of different types of workloads enhances the effectiveness of vamp Future work Collaboration of VMM and OSes for vamp Standard & well-defined API 19/20

20 Thank You! Questions and comments Source code 20/20

Scheduler Support for Video-oriented Multimedia on Client-side Virtualization

Scheduler Support for Video-oriented Multimedia on Client-side Virtualization Hwanju Kim 1, Jinkyu Jeong 1, Jaeho Hwang 1, Joonwon Lee 2, and Seungryoul Maeng 1 Korea Advanced Institute of Science and