Howdy-- I''m running what I believe to be a PV Linux-3.1 domU (on a Linux-3.1 dom0). I''m getting strange patterns of disk access accompanied by short lock-ups. Specifically, the disk will seek audibly 3 to 4 times a second, for a period ranging from 20 seconds to several minutes. There will be short durations in these period where my SSH session is not responsive to keystrokes. When I do: $ top -d .5 on dom0, I see kjournald, some other disk flushing daemon, and qemu-dm. There is nothing interesting on the domU (other than whatever is running--whether it''s the shell, or ./configure, or cc). Seeing qemu-dm in dom0 surprises me, because I thought I was running a PV domU, and I''m under the impression that qemu-dm is strictly for HVM domUs. My setup: * Linux-3.1 / 64-bit-only dom0 (no 32-bit glibc or toolchain) * Linux-3.1 / 64-bit-only domU So my questions are (which I think are related to this issue): * Does anyone have an idea about the strange disk access + brief lockup? * What, exactly, determines a PV guest from an HVM guest? * Is IOMMU relevant when the Intel virtualization is disabled in BIOS? * Do PV guests require any PCI support *XEN_PCI*, *PCI_XEN* in either kernel? * Do PV guests require PVHVM in either kernel? I''d be happy for any insights which may narrow my search... Q