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Wednesday, November 7 • 9:15am - 10:00am
For Performance and Latency, Not for Fun - Jan Kiszka, Siemens

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We are writing the year 2012, and QEMU is still facing a challenge the Linux kernel already overcame: the BQL (Big QEMU Lock). This lock limits both scaling of userspace I/O paths and affects their latency, also preventing the use of QEMU for hard or even soft real-time workloads.

This talk will refresh the problem statement, analyze achievements of the last year and then look into current proposals to proceed with breaking the BQL. Aspects to be covered are

  • abstractions and locking models for MMIO/PIO dispatching
  • locking and execution models for devices and backends
  • conversion strategies (stepwise lock break-downs vs. early cut-through, full vs. selective conversions)
  • device/backend candidates for early adoption

The presentation will be enriched with traps and pitfalls discovered via prototype implementations in the past year and shall trigger further discussions & ideas.


Jan Kiszka

Jan Kiszka is working as consultant and software engineer in the competence center for embedded Linux at Siemens Corporate Technology. He is supporting Siemens sectors with adapting and enhancing open source as platform for their products. For customer pr

Wednesday November 7, 2012 9:15am - 10:00am CET

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