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Re: [Qemu-devel] [RFC PATCH 0/8] MemoryRegion and FlatView refcounting,
From: |
liu ping fan |
Subject: |
Re: [Qemu-devel] [RFC PATCH 0/8] MemoryRegion and FlatView refcounting, replace hostmem with memory_region_find |
Date: |
Thu, 9 May 2013 08:53:27 +0800 |
On Wed, May 8, 2013 at 11:44 PM, Paolo Bonzini <address@hidden> wrote:
> Il 08/05/2013 08:20, liu ping fan ha scritto:
>> On Mon, May 6, 2013 at 10:25 PM, Paolo Bonzini <address@hidden> 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
>>>
>
- [Qemu-devel] [RFC PATCH 2/8] exec: check MRU in qemu_ram_addr_from_host, (continued)
- [Qemu-devel] [RFC PATCH 2/8] exec: check MRU in qemu_ram_addr_from_host, Paolo Bonzini, 2013/05/06
- [Qemu-devel] [RFC PATCH 1/8] memory: add ref/unref calls, Paolo Bonzini, 2013/05/06
- [Qemu-devel] [RFC PATCH 4/8] memory: ref/unref memory across address_space_map/unmap, Paolo Bonzini, 2013/05/06
- [Qemu-devel] [RFC PATCH 3/8] memory: return MemoryRegion from qemu_ram_addr_from_host, Paolo Bonzini, 2013/05/06
- [Qemu-devel] [RFC PATCH 5/8] memory: access FlatView from a local variable, Paolo Bonzini, 2013/05/06
- [Qemu-devel] [RFC PATCH 6/8] memory: use a new FlatView pointer on every topology update, Paolo Bonzini, 2013/05/06
- [Qemu-devel] [RFC PATCH 7/8] memory: add reference counting to FlatView, Paolo Bonzini, 2013/05/06
- [Qemu-devel] [RFC PATCH 8/8] dataplane: replace hostmem with memory_region_find, Paolo Bonzini, 2013/05/06
- Re: [Qemu-devel] [RFC PATCH 0/8] MemoryRegion and FlatView refcounting, replace hostmem with memory_region_find, liu ping fan, 2013/05/08
Re: [Qemu-devel] [RFC PATCH 0/8] MemoryRegion and FlatView refcounting, replace hostmem with memory_region_find, Stefan Hajnoczi, 2013/05/08
Re: [Qemu-devel] [RFC PATCH 0/8] MemoryRegion and FlatView refcounting, replace hostmem with memory_region_find, Stefan Hajnoczi, 2013/05/08