Preventing performance degradation on operating system reboots
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Preventing Performance Degradation on Operating System Reboots. Kenichi Kourai Tokyo Institute of Technology. Motivation. OS reboot is not avoidable Many bugs in OSes Simple method for software rejuvenation Performance degradation after OS reboot The file cache is lost

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Preventing Performance Degradation on Operating System Reboots

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Preventing performance degradation on operating system reboots

Preventing Performance Degradation on Operating System Reboots

Kenichi Kourai

Tokyo Institute of Technology


Motivation

Motivation

  • OS reboot is not avoidable

    • Many bugs in OSes

    • Simple method for software rejuvenation

  • Performance degradation after OS reboot

    • The file cache is lost

    • Disk access conflicts betweenvirtual machines (VMs)

VM

VM

sharedphysical disk


Warm cache reboot

Warm-cache Reboot

  • A new reboot mechanism to prevent the performance degradation

    • Enables an OS to reuse the file cache

    • Preserves the integrity of the file cache

  • Our claim

    • The file cache does not need to be discarded if its integrity is preserved

      • The purpose of OS reboot is to initialize its internal state or to update its components


Preserving the file cache

Preserving the File Cache

  • The warm-cache reboot preserves cache pages on memory during OS reboot

    • The VMM allocates the same memory to VMs

    • The OS maintains a cache-mapping table

cache-mapping

table

cache page

VM

OS

virtual machine monitor (VMM)


Protecting the file cache

Protecting the File Cache

  • Cache pages are write-protected

    • The VMM reads file blocks into a protected cache page

    • The VMM maintains a reuse flag

write-protected

VM

OS

read

set a reuse flag

virtual machine monitor (VMM)

disk


Experiment

Experiment

VMM: Xen 3.0.0

OS: Linux 2.6.12

CPU: dual-core Opteron x2

Memory:12 GB

Disk: Ultra SCSI

  • Power test in DBT-3

    • To examine the performance just afterOS reboot

  • Results

    • Warm-cache reboot

      • No performance degradation

    • Normal reboot

      • Degraded by 67%

after

before


Conclusion

Conclusion

  • We proposed the warm-cache reboot

    • Preserves the file cache during OS reboot

    • Protects cache pages using the VMM

  • Related work

    • Rio file cache [Chen et al.'96]

      • Preserves dirty file cache for reliability

    • Warm-VM reboot [Kourai et al. '07]

      • Preserves VMs during VMM reboot


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