understanding performance interference of io workload in virtualized clooud env

7/25/2019 Understanding Performance Interference of IO Workload in Virtualized Clooud Env

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Understanding Performance

Interference of I/O Workload in

Virtualized Cloud EnvironmentsSummarized by: Michael Riera

9/17/2011

University of Central Florida CDA5532


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Agenda

Purpose

Xen I/O Architecture

Experiment Setup

Experiment Results

Base case Measurement

Interference Analysis

Throughput Interference

Conclusion


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Purpose

The purpose of this paper is to quantify the

interference of multiple VMs on the

throughput of an I/O intensive workload

of 1KB, 4KB, 10KB, 30KB, 50KB, 70KB, 100KB.


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Xen Architecture /Description

Is a popular open-source x86 virtual machine

monitor (VMM) based on virtualization

Technologies

- Hypercalls straight to the host operating system

Lower overhead

PCI Pass through


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Xen Architecture /Description


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Example

NIC Receive Packet

Event Channel (Xen VMM) Decides whether the driver has access to HW

Physical Interface Interface to Network card

Bridge Removes from NIC

Demux the network packet and delivers it to the appropriate VM

Backend Raise a hypercall to the VMM requesting space on the guest

I/O Channel Netback and netfront exchange the page descriptor by page remapping over mechanism over

I/O descriptor ring

Frontend Receives a packet as if it came from a NIC card


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Experiment Setup

IBM ThinkCentre A52 Workstation

3.2Ghz Intel Pentium 4

16KB L1 Cache

2MB L2 Cache2GB 400Mhz DDR memory

Seagate 250GB

Intel NIC E100 PRO/100 Network

Client machinesConnected 1Gb/s lines


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Experiment Setup

I/O intensive workload

Running two isolated guest (VM1, VM2)

VMM Sharing physical hardware

Each VM has equal resources

CPU Scheduling: SMP Credit scheduler

VM1 has an Apache HTTP server

VM2 provides the web services Cache buffer data (no disk reading are involved)


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Experiment Setup


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Experiment Results


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Experiment Results


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Experiment Results

CPU Utilization Measured the average CPU utilization of each VM, including CPU usage of

Dom0, VM1 and VM2

VMM events per second VMM adopts asynchronous hypercall mechanism to notify the VMs of system

events.

VM switches Metric for number of times VMM need to context switch

I/O count Pages Exchange

I/O counts per execution Page exchange per execution

VM State Execution state(using CPU), runnable state(waiting for CPU), block state

(waiting for IO)


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Experiment Results


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Experiment Results


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Conclusion

Competing network intensive loads

High Cache misses

High Wait times

ess compe ng resources , p ma

Interference highly sensitive to multiple VMs

Credit Scheduler to blame for large wait in the

larger files compared to the smaller ones

understanding performance interference of io workload in virtualized clooud env

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