[HAIFUX LECTURE] vIOMMU: Efficient IOMMU Emulation by Nadav Amit

Eli Billauer eli at billauer.co.il
Sun May 1 11:08:38 IDT 2011

On Monday, May 2nd (TOMORROW), at 18:30, Haifux will gather to hear 
Nadav Amit talk about

   vIOMMU: Efficient IOMMU Emulation


Direct device assignment, where a guest virtual machine directly 
interacts with an I/O device without host intervention, is 
appealing,because it allows an unmodified (non-hypervisor-aware) guest 
toachieve near-native performance. But device assignment for unmodified 
guests suffers from two serious deficiencies: (1) it requires pinning of 
all the guest's pages, thereby disallowing memory overcommitment,and (2) 
it exposes the guest's memory to buggy device drivers.

We solve these problems by designing, implementing, and exposing an 
emulated IOMMU (vIOMMU) to the unmodified guest. We employ two novel 
optimizations to make vIOMMU perform well: (1) waiting a few 
milliseconds before tearing down an IOMMU mapping in the hope it will be 
immediately reused (``optimistic teardown''), and (2) running the vIOMMU 
on a sidecore, and thereby enabling for the first time the use of a side 
core by unmodified guests. Both optimizations are highly effective in 
isolation. The former allows bare-metal to achieve 100%of a 10Gbps line 
rate. The combination of the two allows an unmodified guest to do the 
same.ools used to track and count I/O (including - why is process-based 
I/O accounting so tricky).


We meet in Taub (CS Faculty) building, room 6. For instructions see: 

Attendance is free, and you are all invited!


Future Haifux talks include:

16/5/2011 The anatomy of a PCI/PCI Express (Linux) kernel driver by Eli 
30/5/2011 How to Spread Knowledge Throughout the World While Wearing 
Only Your Slippers by Tomer Ashur.
13/6/2011 SSD fundamentals by Amit Berman

We are always interested in hearing your talks and ideas. If you wish to 
give a talk, hold a discussion, or just plan some event haifux might be 
interested in, please contact us at webmaster at haifux.org

Web: http://www.billauer.co.il

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