Message-id: <1506863811.1916.1.camel@icloud.com>
Date:   Sun, 01 Oct 2017 15:16:51 +0200
From:   Damian Tometzki <damian.tometzki@...oud.com>
To:     Wei Wang <wei.w.wang@...el.com>, virtio-dev@...ts.oasis-open.org,
        linux-kernel@...r.kernel.org, qemu-devel@...gnu.org,
        virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org,
        linux-mm@...ck.org, mst@...hat.com, mhocko@...nel.org,
        akpm@...ux-foundation.org, mawilcox@...rosoft.com
Cc:     david@...hat.com, cornelia.huck@...ibm.com,
        mgorman@...hsingularity.net, aarcange@...hat.com,
        amit.shah@...hat.com, pbonzini@...hat.com, willy@...radead.org,
        liliang.opensource@...il.com, yang.zhang.wz@...il.com,
        quan.xu@...yun.com
Subject: Re: [PATCH v16 0/5] Virtio-balloon Enhancement

Hello,

where i can found the patch in git.kernel.org ?


Am Samstag, den 30.09.2017, 12:05 +0800 schrieb Wei Wang:
> This patch series enhances the existing virtio-balloon with the
> following
> new features:
> 1) fast ballooning: transfer ballooned pages between the guest and
> host in
> chunks using sgs, instead of one array each time; and
> 2) free page block reporting: a new virtqueue to report guest free
> pages
> to the host.
> 
> The second feature can be used to accelerate live migration of VMs.
> Here
> are some details:
> 
> Live migration needs to transfer the VM's memory from the source
> machine
> to the destination round by round. For the 1st round, all the VM's
> memory
> is transferred. From the 2nd round, only the pieces of memory that
> were
> written by the guest (after the 1st round) are transferred. One
> method
> that is popularly used by the hypervisor to track which part of
> memory is
> written is to write-protect all the guest memory.
> 
> The second feature enables the optimization of the 1st round memory
> transfer - the hypervisor can skip the transfer of guest free pages
> in the
> 1st round. It is not concerned that the memory pages are used after
> they
> are given to the hypervisor as a hint of the free pages, because they
> will
> be tracked by the hypervisor and transferred in the next round if
> they are
> used and written.
> 
> Change Log:
> v15->v16:
> 1) mm: stop reporting the free pfn range if the callback returns
> false;
> 2) mm: move some implementaion of walk_free_mem_block into a function
> to
> make the code layout looks better;
> 3) xbitmap: added some optimizations suggested by Matthew, please
> refer to
> the ChangLog in the xbitmap patch for details.
> 4) xbitmap: added a test suite
> 5) virtio-balloon: bail out with a warning when virtqueue_add_inbuf
> returns
> an error
> 6) virtio-balloon: some small code re-arrangement, e.g. detachinf
> used buf
> from the vq before adding a new buf
> 
> v14->v15:
> 1) mm: make the report callback return a bool value - returning 1 to
> stop
> walking through the free page list.
> 2) virtio-balloon: batching sgs of balloon pages till the vq is full
> 3) virtio-balloon: create a new workqueue, rather than using the
> default
> system_wq, to queue the free page reporting work item.
> 4) virtio-balloon: add a ctrl_vq to be a central control plane which
> will
> handle all the future control related commands between the host and
> guest.
> Add free page report as the first feature controlled under ctrl_vq,
> and
> the free_page_vq is a data plane vq dedicated to the transmission of
> free
> page blocks.
> 
> v13->v14:
> 1) xbitmap: move the code from lib/radix-tree.c to lib/xbitmap.c.
> 2) xbitmap: consolidate the implementation of xb_bit_set/clear/test
> into
> one xb_bit_ops.
> 3) xbitmap: add documents for the exported APIs.
> 4) mm: rewrite the function to walk through free page blocks.
> 5) virtio-balloon: when reporting a free page blcok to the device, if
> the
> vq is full (less likey to happen in practice), just skip reporting
> this
> block, instead of busywaiting till an entry gets released.
> 6) virtio-balloon: fail the probe function if adding the signal buf
> in
> init_vqs fails.
> 
> v12->v13:
> 1) mm: use a callback function to handle the the free page blocks
> from the
> report function. This avoids exposing the zone internal to a kernel
> module.
> 2) virtio-balloon: send balloon pages or a free page block using a
> single
> sg each time. This has the benefits of simpler implementation with no
> new
> APIs.
> 3) virtio-balloon: the free_page_vq is used to report free pages only
> (no
> multiple usages interleaving)
> 4) virtio-balloon: Balloon pages and free page blocks are sent via
> input
> sgs, and the completion signal to the host is sent via an output sg.
> 
> v11->v12:
> 1) xbitmap: use the xbitmap from Matthew Wilcox to record ballooned
> pages.
> 2) virtio-ring: enable the driver to build up a desc chain using
> vring
> desc.
> 3) virtio-ring: Add locking to the existing START_USE() and END_USE()
> macro to lock/unlock the vq when a vq operation starts/ends.
> 4) virtio-ring: add virtqueue_kick_sync() and virtqueue_kick_async()
> 5) virtio-balloon: describe chunks of ballooned pages and free pages
> blocks directly using one or more chains of desc from the vq.
> 
> v10->v11:
> 1) virtio_balloon: use vring_desc to describe a chunk;
> 2) virtio_ring: support to add an indirect desc table to virtqueue;
> 3)  virtio_balloon: use cmdq to report guest memory statistics.
> 
> v9->v10:
> 1) mm: put report_unused_page_block() under CONFIG_VIRTIO_BALLOON;
> 2) virtio-balloon: add virtballoon_validate();
> 3) virtio-balloon: msg format change;
> 4) virtio-balloon: move miscq handling to a task on
> system_freezable_wq;
> 5) virtio-balloon: code cleanup.
> 
> v8->v9:
> 1) Split the two new features, VIRTIO_BALLOON_F_BALLOON_CHUNKS and
> VIRTIO_BALLOON_F_MISC_VQ, which were mixed together in the previous
> implementation;
> 2) Simpler function to get the free page block.
> 
> v7->v8:
> 1) Use only one chunk format, instead of two.
> 2) re-write the virtio-balloon implementation patch.
> 3) commit changes
> 4) patch re-org
> 
> Matthew Wilcox (2):
>   lib/xbitmap: Introduce xbitmap
>   radix tree test suite: add tests for xbitmap
> 
> Wei Wang (3):
>   virtio-balloon: VIRTIO_BALLOON_F_SG
>   mm: support reporting free page blocks
>   virtio-balloon: VIRTIO_BALLOON_F_CTRL_VQ
> 
>  drivers/virtio/virtio_balloon.c         | 437
> +++++++++++++++++++++++++++++---
>  include/linux/mm.h                      |   6 +
>  include/linux/radix-tree.h              |   2 +
>  include/linux/xbitmap.h                 |  66 +++++
>  include/uapi/linux/virtio_balloon.h     |  16 ++
>  lib/Makefile                            |   2 +-
>  lib/radix-tree.c                        |  42 ++-
>  lib/xbitmap.c                           | 264 +++++++++++++++++++
>  mm/page_alloc.c                         |  91 +++++++
>  tools/include/linux/bitmap.h            |  34 +++
>  tools/include/linux/kernel.h            |   2 +
>  tools/testing/radix-tree/Makefile       |   7 +-
>  tools/testing/radix-tree/linux/kernel.h |   2 -
>  tools/testing/radix-tree/main.c         |   5 +
>  tools/testing/radix-tree/test.h         |   1 +
>  tools/testing/radix-tree/xbitmap.c      | 269 ++++++++++++++++++++
>  16 files changed, 1203 insertions(+), 43 deletions(-)
>  create mode 100644 include/linux/xbitmap.h
>  create mode 100644 lib/xbitmap.c
>  create mode 100644 tools/testing/radix-tree/xbitmap.c
> 

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