Il 13/09/2012 22:12, Nicholas A. Bellinger ha scritto: >> > Are you still seeing the performance degradation discussed in the thread >> > >> > "vhost-scsi port to v1.1.0 + MSI-X performance regression" >> > > So the performance regression reported here with QEMU v1.2-rc + > virtio-scsi ended up being related to virtio interrupts being delivered > across multiple CPUs. > > After explicitly setting the IRQ affinity of the virtio0-request MSI-X > vector to a specific CPU, the small block (4k) mixed random I/O > performance jumped back up to the expected ~100K IOPs for a single LUN.
Have you tried setting rq_affinity to 2? Benchmarking this against multiqueue virtio-scsi is on my todo list. Paolo > FYI, I just tried this again with the most recent QEMU v1.2.50 (v1.3-rc) > code, and both cases appear to be performing as expected once again > regardless of the explicit IRQ affinity setting.
