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Re: [Qemu-devel] [RFC PATCH qemu 0/4] memory: Reduce memory use
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [RFC PATCH qemu 0/4] memory: Reduce memory use |
Date: |
Thu, 7 Sep 2017 10:51:42 +0100 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
* Alexey Kardashevskiy (address@hidden) wrote:
> This was inspired by https://bugzilla.redhat.com/show_bug.cgi?id=1481593
>
> What happens ithere is that every virtio block device creates 2 address
> spaces - for modern config space (called "virtio-pci-cfg-as") and
> for busmaster (common pci thing, called after the device name,
> in my case "virtio-blk-pci").
>
> Each address_space_init() updates topology for every address space.
> Every topology update (address_space_update_topology()) creates a new
> dispatch tree - AddressSpaceDispatch with nodes (1KB) and
> sections (48KB) and destroys the old one.
>
> However the dispatch destructor is postponed via RCU which does not
> get a chance to execute until the machine is initialized but before
> we get there, memory is not returned to the pool, and this is a lot
> of memory which grows n^2.
>
> These patches are trying to address the memory use and boot time
> issues but tbh only the first one provides visible outcome.
Do you have a feel for how much memory is saved?
Dave
> There are still things to polish and double check the use of RCU,
> I'd like to get any feedback before proceeding - is this going
> the right way or way too ugly?
>
>
> This is based on sha1
> 1ab5eb4efb Peter Maydell "Update version for v2.10.0 release".
>
> Please comment. Thanks.
>
>
>
> Alexey Kardashevskiy (4):
> memory: Postpone flatview and dispatch tree building till all devices
> are added
> memory: Prepare for shared flat views
> memory: Share flat views and dispatch trees between address spaces
> memory: Add flat views to HMP "info mtree"
>
> include/exec/memory-internal.h | 6 +-
> include/exec/memory.h | 93 +++++++++----
> exec.c | 242 +++++++++++++++++++--------------
> hw/alpha/typhoon.c | 2 +-
> hw/dma/rc4030.c | 4 +-
> hw/i386/amd_iommu.c | 2 +-
> hw/i386/intel_iommu.c | 9 +-
> hw/intc/openpic_kvm.c | 2 +-
> hw/pci-host/apb.c | 2 +-
> hw/pci/pci.c | 3 +-
> hw/ppc/spapr_iommu.c | 4 +-
> hw/s390x/s390-pci-bus.c | 2 +-
> hw/vfio/common.c | 6 +-
> hw/virtio/vhost.c | 6 +-
> memory.c | 299
> +++++++++++++++++++++++++++--------------
> monitor.c | 3 +-
> vl.c | 4 +
> hmp-commands-info.hx | 7 +-
> 18 files changed, 448 insertions(+), 248 deletions(-)
>
> --
> 2.11.0
>
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-devel] [RFC PATCH qemu 1/4] memory: Postpone flatview and dispatch tree building till all devices are added, (continued)
[Qemu-devel] [RFC PATCH qemu 3/4] memory: Share flat views and dispatch trees between address spaces, Alexey Kardashevskiy, 2017/09/07
[Qemu-devel] [RFC PATCH qemu 2/4] memory: Prepare for shared flat views, Alexey Kardashevskiy, 2017/09/07
Re: [Qemu-devel] [RFC PATCH qemu 0/4] memory: Reduce memory use,
Dr. David Alan Gilbert <=