Harmonizing Performance and Isolation in Microkernels with Efficient Intra-kernel

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" summary

UnderBridge redesigns microkernels by moving system servers into kernel space while enforcing isolation with Intel PKU/MPK, implementing a fast IPC gate that yields an IPC roundtrip as low as 109 cycles. The team builds ChCore and ports the design to seL4, Google Zircon, and Fiasco.OC, claiming up to 3.0× faster IPC than SkyBridge and up to 13.1× improvement on IPC‑heavy workloads. The design supports up to 16 PKU domains, server migration between user and kernel, and prevents privileged‑instruction escapes via VM exits plus targeted binary rewriting.

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" chapters (18)

1. 0:00Intro
2. 0:23Monolithic Kernel and Microkernel
3. 1:16Benefits and Usages of Microkernel
4. 1:49Expensive Communication Cost • Tradeoff: Performance and Isolation - Inter-process communication (IPC) overhead
5. 2:53IPC Overhead is considerable
6. 3:57Goal: Both Ends
7. 4:09New Hardware Brings Opportunities PKU: Protection Key for Userspace (aka. MPK) - Assign each page one PKEY (i.e., memory domain ID) PTE
8. 5:12Efficient Intra-Process Isolation
9. 6:00Intra-Process Isolation + Microkernel
10. 6:24Design Choice #2
11. 9:02UnderBridge: Sinking System Servers
12. 9:24Design Choice #3: UnderBridge Build execution domains in the kernel page table
13. 12:12IPC Gate
14. 13:37Server Migration
15. 15:10Privilege Deprivation
16. 17:40Other Designs and Implementations
17. 17:54Cross-server IPC Round-Trip Latency
18. 18:49SQLite Throughput under YCSB-A

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