Re: [Qemu-devel] KVM call agenda for 2013-04-09

[Stefan Hajnoczi]

Meeting notes on Abel's presentation:

Aim: improve vhost scalability

Shared vhost thread
==============
Problem: Linux scheduler does not see state of virtqueues, cannot make
good scheduling decisions
Solution: Shared thread serves multiple VMs and therefore influences
"I/O scheduling" instead of kernel thread per vhost device

Exitless communication
=================
 * Polling on host to notice guest vring updates without guest pio instruction
   * Use CPU affinity to bind vcpus to separate cores and let polling
run on dedicated cores
 * Existless Interrupt (ELI) or future hardware APIC virtualization
feature to inject virtual interrupts
without vmexit and EOI

See paper for performance results (impressive numbers):
http://domino.research.ibm.com/library/cyberdig.nsf/papers/479E3578ED05BFAC85257B4200427735/$File/h-0319.pdf

Abel will publish rebased code on GitHub but does not have time to
upstream them.

The next step: QEMU/KVM community can digest the paper + patches and
decide on ideas to upstream.