From: "Michael S. Tsirkin" <mst@redhat.com>
To: "Eugenio Pérez" <eperezma@redhat.com>
Cc: Parav Pandit <parav@mellanox.com>,
Markus Armbruster <armbru@redhat.com>,
qemu-devel@nongnu.org, Harpreet Singh Anand <hanand@xilinx.com>,
Xiao W Wang <xiao.w.wang@intel.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
Eli Cohen <eli@mellanox.com>,
virtualization@lists.linux-foundation.org,
Eric Blake <eblake@redhat.com>, Michael Lilja <ml@napatech.com>
Subject: Re: [RFC v3 00/29] vDPA software assisted live migration
Date: Mon, 24 May 2021 05:38:05 -0400 [thread overview]
Message-ID: <20210524053144-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20210519162903.1172366-1-eperezma@redhat.com>
On Wed, May 19, 2021 at 06:28:34PM +0200, Eugenio Pérez wrote:
> Commit 17 introduces the buffer forwarding. Previous one are for
> preparations again, and laters are for enabling some obvious
> optimizations. However, it needs the vdpa device to be able to map
> every IOVA space, and some vDPA devices are not able to do so. Checking
> of this is added in previous commits.
That might become a significant limitation. And it worries me that
this is such a big patchset which might yet take a while to get
finalized.
I have an idea: how about as a first step we implement a transparent
switch from vdpa to a software virtio in QEMU or a software vhost in
kernel?
This will give us live migration quickly with performance comparable
to failover but without dependance on guest cooperation.
Next step could be driving vdpa from userspace while still copying
packets to a pre-registered buffer.
Finally your approach will be a performance optimization for devices
that support arbitrary IOVA.
Thoughts?
--
MST
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next parent reply other threads:[~2021-05-24 9:38 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210519162903.1172366-1-eperezma@redhat.com>
2021-05-24 9:38 ` Michael S. Tsirkin [this message]
[not found] ` <CAJaqyWcVm55qjaDpQsuLzaY0FCzjW2ARyvOWCdfS9RJNoOM7Aw@mail.gmail.com>
2021-05-24 11:29 ` [RFC v3 00/29] vDPA software assisted live migration Michael S. Tsirkin
2021-07-19 14:13 ` Stefan Hajnoczi
2021-05-25 0:09 ` Jason Wang
[not found] ` <20210519162903.1172366-7-eperezma@redhat.com>
2021-05-26 1:06 ` [RFC v3 06/29] virtio-net: Honor VIRTIO_CONFIG_S_DEVICE_STOPPED Jason Wang
2021-05-26 1:10 ` Jason Wang
[not found] ` <CAJaqyWeV+za=xeKHb9vn=Y+0mfekCb8w5dmWNMgzQ6uOtU3jxw@mail.gmail.com>
2021-06-03 3:12 ` Jason Wang
[not found] ` <20210519162903.1172366-14-eperezma@redhat.com>
2021-05-26 1:14 ` [RFC v3 13/29] vhost: Add vhost_get_iova_range operation Jason Wang
[not found] ` <CAJaqyWeL-0KjsBcXs1tYdvn9xLAK-x0Sb+RFuzPgngXxYtF9uw@mail.gmail.com>
2021-05-27 4:51 ` Jason Wang
[not found] ` <CAJaqyWf+=-nwOsS=zZEhmiTA_TotVMQibUgE0grCMZgXVDNpxg@mail.gmail.com>
2021-06-03 3:13 ` Jason Wang
[not found] ` <20210519162903.1172366-16-eperezma@redhat.com>
2021-05-31 9:01 ` [RFC v3 15/29] vhost: Add enable_custom_iommu to VhostOps Jason Wang
[not found] ` <20210519162903.1172366-22-eperezma@redhat.com>
2021-05-31 9:40 ` [RFC v3 21/29] vhost: Add VhostIOVATree Jason Wang
[not found] ` <CAJaqyWfKTiKeKLLjB9qDf4qJwL420YRo6FrJgozp_tn0Z57pOA@mail.gmail.com>
2021-07-14 3:04 ` Jason Wang
[not found] ` <CAJaqyWdZtvUM0_O1BiZNMkkgJEa_yrOh=XDgjTt2byZwU9J8tQ@mail.gmail.com>
[not found] ` <CAJaqyWePZSo8-q=d3fWBGUwgM8EfHHVYgR_KGKxjcgeZn5C=Vw@mail.gmail.com>
2021-07-14 9:33 ` Jason Wang
[not found] ` <20210519162903.1172366-18-eperezma@redhat.com>
2021-06-02 9:50 ` [RFC v3 17/29] vhost: Shadow virtqueue buffers forwarding Jason Wang
[not found] ` <CAJaqyWf7M1fjrd+kr-2bcYj+ibrqZVoREZuTiJ0i+p6dA+Dukw@mail.gmail.com>
2021-06-03 3:34 ` Jason Wang
[not found] ` <20210519162903.1172366-26-eperezma@redhat.com>
2021-06-02 9:51 ` [RFC v3 25/29] vhost: Add custom IOTLB translations to SVQ Jason Wang
[not found] ` <CAJaqyWc7OWeQnXHihY=mYp=N+rRJLcbFUsJA-OszD6tyr6v-FQ@mail.gmail.com>
2021-06-03 3:39 ` Jason Wang
2021-06-02 9:59 ` [RFC v3 00/29] vDPA software assisted live migration Jason Wang
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