ISCA Day 1

LAP: Loop-Block Aware Inclusion Properties for Energy-Efficient Asymmetric Last Level Caches

Adaptive selection between inclusive and exclusive cache based on the LLC misses and memory traffic?

This work is of interest, and I should take a look at it.

Loop blocks are used as guides to the adaptive inclusive/exclusive cache.


Short-Circuit Dispatch: Accelerating Virtual Machine Interpreters on Embedded Processors

Scripting languages offer ease of programming and natural support for event-driven programming model. However, too slow.

Recurring inefficiency of bytecode dispatch loop.

Fetches a bytcode, and doecode, bounds checking, jump address calculation, jump, execute bytecode.

This dispatcher code takes 10~30% of total instruction counts.

There are a few problems:

  • Hard to predice inderict jumps.
  • Redundunt calculations
  • This work solves the two problems above by using the BTB (with bytecode as key!)

Use the BTB using the bytecode as key (not PC)

  • Hits short-circuit to correct bytecode hanlder
  • Miss falls back to the original slow path

A Measurement Study of ARM Virtualization Performance

KVM & Xen was used to compare ARM & x86

ARM on Xen can be 4x fast for Hypercalls
4x slower on KVM

This is because Xen is a bare-metal hypervisor.

KVM is type 2 hypervisor. Runs app & virtual machine.

ARM EL2 (hypervisor privelege) is designed for simple hardware (Xen)

KVM does a lot better for Virtualized I/O – Hosted Hypervisor is running with linux in the same level that is sophisticated enough to execute I/O

Xen requires switcing from VM->Xen->Dom0->Xen->HW, Thus a lot of traps!

VHE (Virtualization host extension?) Allows KVM ARM to run on EL2 (Hypervisor priviledge)


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