• Share
  • Email
  • Embed
  • Like
  • Save
  • Private Content
* Distributed System Lab 1 Analysis and experimental ...
 

* Distributed System Lab 1 Analysis and experimental ...

on

  • 477 views

 

Statistics

Views

Total Views
477
Views on SlideShare
475
Embed Views
2

Actions

Likes
0
Downloads
1
Comments
0

1 Embed 2

http://www.slideshare.net 2

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment
  • Asdfdffef Wef Wef We F F Ew Fewf Ewfewfewfwf We F Wef We F ewf

* Distributed System Lab 1 Analysis and experimental ... * Distributed System Lab 1 Analysis and experimental ... Presentation Transcript

  • Analysis and experimental evaluation of data plane virtualization with Xen 04/03/10 Distributed System Lab 游清權
  • Outline
    • Introduction
    • Virtual Network with Xen
      • Data path in Xen
      • Routers data plane virtualization with Xen
      • Performance problem statement
    • Experiments and Analysis
    • Related work
    • Conclusion and perspectives
    04/03/10 Distributed System Lab
  • Introduction
    • System virtualization
      • Isolation
      • Mobility
      • Dynamic reconfiguration
      • Fault tolerance of distributed systems
      • Increase security due to the isolation
    04/03/10 Distributed System Lab
  • Introduction
    • Virtualization could potentially solve main issues of the actual Internet (security, mobility, eliability,configurability)
      • Overhead due to the additional layers
    • Considering this sharing of resources like the
      • network interfaces
      • the processors
      • the memory(buffer space)
      • the switching fabric
    • It is a challenge to get a predictable, stable and optimal performance!
    04/03/10 Distributed System Lab
  • Virtual Network with Xen
    • Data path in Xen
    04/03/10 Distributed System Lab
  • Data path in Xen
    • VMs in Xen access the network hardware through the virtualization layer
    • domU has a virtual interface for each physical network interface
    • Virtual interface be accessed via a split device driver ( frontend driver in domU , the backend driver in dom0 )
    04/03/10 Distributed System Lab
  • 1.Data path in Xen
    • Network packets emitted on a VM
    • Copied to a segment of shared memory by the Xen hypervisor , transmitted to dom0
    • Packets are bridged (path 1), routed (path 2) between the virtual interfaces and the physical ones
    • The additional path a packet (dashed line)
    • Overhead:
      • Copy the shared memory,
      • multiplexing and demultiplexing
    04/03/10 Distributed System Lab
  • 2.Routers data plane virtualization with Xen
    • Xen can be used for fully (i. e. control plane and data plane) virtualized software routers
    • Figure 2 .Architecture with software routers uploaded into two virtual machines to create virtual routers
    • VM not direct access to the physical hardware interfaces
    • Packets are forwarded between the virtual interface and corresponding physical interface (multiplexing and demultiplexing)
    04/03/10 Distributed System Lab
  • 04/03/10 Distributed System Lab
  • 3.Performance problem statement 04/03/10 Distributed System Lab
  • 3.Performance problem statement
    • Define the efficiency in terms of throughput
    • Fairness of the inter-virtual machine resource sharing is derived from the classical Jain index[6]
    • n : Number of VMs sharing the physical resources
    • Xi: The metric achieved by each virtual machine I
    04/03/10 Distributed System Lab
  • Experiments and Analysis
    • 1.Experimental setup
    • All executed on the fully controlled, reservable and reconfigurable French national testbed Grid’5000 [4].
    • End-hosts are IBM eServers 325
      • With 2 CPUs AMD Opteron 246 (2.0 GHz/1MB)
      • With one core each one
      • 2GB of memory and a 1Gb/s NIC.
    04/03/10 Distributed System Lab
  • Experiments and Analysis
    • Virtual routers host on IBM eServers 326m
      • With 2 CPUs AMD Opteron 246 (2.0GHz/1MB),
      • With one core each one
      • 2GB of memory and 2 1Gb/s NICs.
    • Xen 3.1.0 and 3.2.1 with respectively the modified 2.6.18-3 and 2.6.18.8 linux kernels
    • Measurement tools
      • iperf for TCP throughput
      • netperf for UDP rate
      • xentop for the CPU utilization
      • classical ping utility for latency
    04/03/10 Distributed System Lab
  • Experiments and Analysis
    • Evaluation of virtual end-hosts
      • Network performance on virtual end-hosts implemented with Xen 3.1 and Xen 3.2.
      • Some results with Xen 3.1 were not satisfying , dom0 being the bottleneck.
      • Second run of the on Xen 3.1 , attributing more CPU time to dom0, (up to 32 times the part attributed to a domU) called Xen 3.1a.
    04/03/10 Distributed System Lab
  • Sending performance
    • First experiment
      • TCP sending throughput on 1, 2, 4 and 8 virtual hosts
      • Figure 3:Throughput per VM , Aggregate throughput.
      • 3.1 and 3.2, close to classical linux throughput R classical(T/R) = 938Mb/s
      • 3.1a and 3.2, aggregated throughput obtained by VMs reaches roughly more than on 3.1
    04/03/10 Distributed System Lab
  • 04/03/10 Distributed System Lab
  • Sending performance
    • Conclude in three cases
      • The system is efficient and predictable (Throughput)
    • The throughput per VM corresponds to the fair share of the available bandwidth of the link (Rtheoretical/N).
    04/03/10 Distributed System Lab
  • Sending performance
    • Average CPU utilization for each guest domain Figure 4 .
    • For a single domU
      • Two CPUs are used at around 50% in the three setups (Xen 3.1, 3.1a and 3.2)
    • Linux system without virtualization :
      • only Cclassical(E) = 32% of both CPUs are in use
    • With 8 domUs
      • Both of the CPUs are used at over 70%
    04/03/10 Distributed System Lab
  • 04/03/10 Distributed System Lab
  • Sending performance
    • 3.1a : Increasing dom0’s CPU weight
    • Even if virtualization introduces a processing overhead , two processors can allow to achieve a throughput equivalent to the Max theoretical throughput on 8 concurrent VMs using a 1Gb/s link.
    • Fairness index is here close to 1 (bandwidth and CPU time are fairly)
    04/03/10 Distributed System Lab
  • 2.Receiving performance
    • Figure 5
    • Xen 3.1: Aggregate throughput decreases slightly
      • (according to the number of VM)
    • Only 882Mb/s on a single domU
    • Only 900Mb/s on a set of 8 concurrent domUs
      • What corresponds to around 95% of the throughput Rclassical(T/R) = 938Mb/s on a classical linux system.
    04/03/10 Distributed System Lab
  • Receiving performance.
    • The efficiency E throughput
      • Varies between 0.96 for 8 domUs and 0.94 for a single domU
    • By changing scheduler parameters (Xen3.1a)
      • Improve the aggregate throughput to reach about 970Mb/s on 8 virtual machines.
    04/03/10 Distributed System Lab
  • Receiving performance
    • Xen 3.1, bandwidth between the domUs is very unfair (Growing number of domUs)
    • Unfair treatment of the events and has been fixed in Xen 3.2.
    • To provide simply dom0 with more CPU time
      • 3.1a improve fairness in Xen 3.1 by giving dom0 enough time to treat all the events
    04/03/10 Distributed System Lab
  • Receiving performance
    • Fair resource sharing:
      • Makes performance much more predictable
    • Xen 3.2 is similar to Xen 3.1a
      • Throughput increases by about 6%
      • (compared to the default 3.1 version)
    04/03/10 Distributed System Lab
  • Receiving performance 04/03/10 Distributed System Lab
  • Receiving performance
    • Total CPU cost
      • Varie between 70% and 75%(Xen3.1 and 3.2)
      • (important overhead compared to linux system without virtualization)
      • Network reception takes C classical(R) = 24%
    • Notice that on default Xen 3.1
      • The efficiency in terms of throughput decreases, but the available CPU time is not entirely consumed
      • Unfairness
    04/03/10 Distributed System Lab
  • Receiving performance
    • Proposal improves fairness but increases CPU
    • Xen 3.2
      • DomUs CPU sharing is fair (dom0’s CPU decreases slightly)
      • Less total CPU overhead and achieving however better throughput
    • Conclude:
      • Important improvements have been implemented in Xen 3.2 to decrease the excessive dom0 CPU overhead.
    04/03/10 Distributed System Lab
  • Receiving performance 04/03/10 Distributed System Lab
  • 3.Evaluation of virtual routers
    • Forwarding performance of virtual routers with 2 NICs
      • UDP receiving throughput over VMs
      • Sending Max sized packets on Max link speed over the virtual routers and the TCP throughput is measured.
      • Further Latency over virtual routers is measured
    • Xen 3.2a
      • Xen 3.2 in its default configuration
      • Increased weight parameter for dom0 in CPU scheduling
    04/03/10 Distributed System Lab
  • 3.Evaluation of virtual routers
    • Forwarding performance.
    04/03/10 Distributed System Lab
  • 3.Evaluation of virtual routers
    • Performance of virtual routers
      • Generate UDP traffic over one or several virtual routers (1 to 8) sharing a single physical machine
        • Max(1500 bytes)
        • min (64 bytes)
    • Figure 7 ,obtained UDP bit rate and TCP throughput
    • Packet loss rate with Max sized packets on each VM
    • 1 − Rtheoretical/(N × Rtheoretical)
    • Classical linux router Rclassical(F) = 957Mb/s
    04/03/10 Distributed System Lab
  • 3.Evaluation of virtual routers
    • Details the UDP packet rates and the loss rates per domU with Max and min sized packets.
    04/03/10 Distributed System Lab
  • 3.Evaluation of virtual routers
    • Aggregate UDP some cases a bit higher than theoretical value
      • Due to little variation in the start times of the different flows
    • Resource sharing is fair
      • Performance of this setup is predictable
    • With min sized packets on 4 or 8 virtual routers , dom0 becomes too overloaded
    • Giving a bigger CPU part to dom0 (Xen 3.2a)
      • Overall TCP throughput increases
    04/03/10 Distributed System Lab
  • 3.Evaluation of virtual routers
    • Virtual router(VR) latency.
      • Concurrent virtual routers sharing the same physical machine are either idle or stressed forwarding Max rate TCP flows.
    04/03/10 Distributed System Lab
  • Related work
    • Performance of virtual packet transmission in Xen is a crucial subject and has been treated in several papers
    04/03/10 Distributed System Lab
  • Conclusion and perspectives
    • Virtualization mechanisms are costly
      • Additional copy
      • I/O scheduling of virtual machines sharing the physical devices
    • Virtualizing the data plane by forwarding packets in domU becomes a more and more promising approach
    04/03/10 Distributed System Lab
  • Conclusion and perspectives
    • End-host throughput improved in Xen 3.2 compared to 3.1
    • Virtual routers act similar to classical linux routers forwarding big packets.
    • Latency is impacted by the number of concurrent virtual routers .
    • Our next goal is to evaluate the performance on 10 Gbit/s links and implement virtual routers on the Grid’5000 platform.
    04/03/10 Distributed System Lab