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