On Wed, May 8, 2013 at 11:44 PM, Paolo Bonzini <pbonz...@redhat.com> wrote: > Il 08/05/2013 08:20, liu ping fan ha scritto: >> On Mon, May 6, 2013 at 10:25 PM, Paolo Bonzini <pbonz...@redhat.com> wrote: >>> Hi, >>> >>> this is an alternative approach to refactoring of dataplane's HostMem >>> code. Here, I take Ping Fan's idea of RCU-style updating of the >>> region list and apply it to the AddressSpace's FlatView. With this >> >> In fact, I am worrying about the priority of MemoryListener, if it is >> true, then we should drop RCU-style idea. > > You mean in hostmem, or in general as in this patch? Note that this > patch releases the old FlatView at the end of all MemoryListener operations. > Both in hostmem and this patch, they all broke the original design of the MemoryListener, see notes for priority in code. I have set out 2 patches to highlight this issue, and have CC you and Stefanha.
Regards, Pingfan > Paolo > >> Also if it is true, there is >> already a bug with hostmem listener. It should use region_del, not >> region_nop to reconstruct the local view. But just let me have a deep >> thinking. >> >> Regards, >> Pingfan >>> change, dataplane can simply use memory_region_find instead of >>> hostmem. >>> >>> This is a somewhat larger change, but I prefer it for two reasons. >>> >>> 1) it splits the task of adding BQL-less memory dispatch in two parts, >>> tacking memory_region_find first (which is simpler because locking >>> is left to the caller). >>> >>> 2) HostMem duplicates a lot of the FlatView logic, and adding the >>> RCU-style update in FlatView benefits everyone. >>> >>> The missing ingredients here are: >>> >>> 1) remember and unreference the MemoryRegions that are used in >>> a vring entry. In order to implement this, it is probably simpler >>> to change vring.c to use virtio.c's VirtQueueElement data structure. >>> We want something like that anyway in order to support migration. >>> >>> 2) add an owner field to MemoryRegion, and set it for all MemoryRegions >>> for hot-unpluggable devices. In this series, ref/unref are stubs. >>> >>> For simplicity I based the patches on my IOMMU rebase. I placed the >>> tree at git://github.com/bonzini/qemu.git, branch iommu. >>> >>> Paolo >>> >>> Paolo Bonzini (8): >>> memory: add ref/unref calls >>> exec: check MRU in qemu_ram_addr_from_host >>> memory: return MemoryRegion from qemu_ram_addr_from_host >>> memory: ref/unref memory across address_space_map/unmap >>> memory: access FlatView from a local variable >>> memory: use a new FlatView pointer on every topology update >>> memory: add reference counting to FlatView >>> dataplane: replace hostmem with memory_region_find >>> >>> exec.c | 63 +++++++++--- >>> hw/core/loader.c | 1 + >>> hw/display/exynos4210_fimd.c | 6 + >>> hw/display/framebuffer.c | 10 +- >>> hw/i386/kvm/ioapic.c | 2 + >>> hw/i386/kvmvapic.c | 1 + >>> hw/misc/vfio.c | 2 + >>> hw/virtio/dataplane/Makefile.objs | 2 +- >>> hw/virtio/dataplane/hostmem.c | 176 >>> --------------------------------- >>> hw/virtio/dataplane/vring.c | 56 +++++++++-- >>> hw/virtio/vhost.c | 2 + >>> hw/virtio/virtio-balloon.c | 1 + >>> hw/xen/xen_pt.c | 4 + >>> include/exec/cpu-common.h | 2 +- >>> include/exec/memory.h | 9 ++ >>> include/hw/virtio/dataplane/hostmem.h | 57 ----------- >>> include/hw/virtio/dataplane/vring.h | 3 +- >>> kvm-all.c | 2 + >>> memory.c | 142 +++++++++++++++++++++----- >>> target-arm/kvm.c | 2 + >>> target-i386/kvm.c | 4 +- >>> target-sparc/mmu_helper.c | 1 + >>> xen-all.c | 2 + >>> 23 files changed, 253 insertions(+), 297 deletions(-) >>> delete mode 100644 hw/virtio/dataplane/hostmem.c >>> delete mode 100644 include/hw/virtio/dataplane/hostmem.h >>> >