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Re: [Qemu-devel] [RFC PATCH 0/8] MemoryRegion and FlatView refcounting,
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [RFC PATCH 0/8] MemoryRegion and FlatView refcounting, replace hostmem with memory_region_find |
Date: |
Wed, 08 May 2013 17:44:37 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 |
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.
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 0/8] MemoryRegion and FlatView refcounting, replace hostmem with memory_region_find, Paolo Bonzini, 2013/05/06
- [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,
Paolo Bonzini <=
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