From: "Li, Liang Z" <liang.z.li@intel.com>
To: David Hildenbrand <david@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Cc: "aarcange@redhat.com" <aarcange@redhat.com>,
"virtio-dev@lists.oasis-open.org"
<virtio-dev@lists.oasis-open.org>,
"Hansen, Dave" <dave.hansen@intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"mst@redhat.com" <mst@redhat.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"virtualization@lists.linux-foundation.org"
<virtualization@lists.linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"amit.shah@redhat.com" <amit.shah@redhat.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"dgilbert@redhat.com" <dgilbert@redhat.com>
Subject: RE: [PATCH v6 kernel 0/5] Extend virtio-balloon for fast (de)inflating & fast live migration
Date: Wed, 18 Jan 2017 13:29:59 +0000 [thread overview]
Message-ID: <F2CBF3009FA73547804AE4C663CAB28E3C356F1B__33066.8158516803$1484746239$gmane$org@shsmsx102.ccr.corp.intel.com> (raw)
In-Reply-To: <2a32f616-25a8-ba5a-f74c-d619fc8ab333@redhat.com>
> Am 21.12.2016 um 07:52 schrieb Liang Li:
> > This patch set contains two parts of changes to the virtio-balloon.
> >
> > One is the change for speeding up the inflating & deflating process,
> > the main idea of this optimization is to use {pfn|length} to present
> > the page information instead of the PFNs, to reduce the overhead of
> > virtio data transmission, address translation and madvise(). This can
> > help to improve the performance by about 85%.
> >
> > Another change is for speeding up live migration. By skipping process
> > guest's unused pages in the first round of data copy, to reduce
> > needless data processing, this can help to save quite a lot of CPU
> > cycles and network bandwidth. We put guest's unused page information
> > in a {pfn|length} array and send it to host with the virt queue of
> > virtio-balloon. For an idle guest with 8GB RAM, this can help to
> > shorten the total live migration time from 2Sec to about 500ms in
> > 10Gbps network environment. For an guest with quite a lot of page
> > cache and with little unused pages, it's possible to let the guest
> > drop it's page cache before live migration, this case can benefit from this
> new feature too.
>
> I agree that both changes make sense (although the second change just
> smells very racy, as you also pointed out in the patch description), however I
> am not sure if virtio-balloon is really the right place for the latter change.
>
> virtio-balloon is all about ballooning, nothing else. What you're doing is using
> it as a way to communicate balloon-unrelated data from/to the hypervisor.
> Yes, it is also about guest memory, but completely unrelated to the purpose
> of the balloon device.
>
> Maybe using virtio-balloon for this purpose is okay - I have mixed feelings
> (especially as I can't tell where else this could go). I would like to get a second
> opinion on this.
>
We have ever discussed the implementation for a long time, making use the current
virtio balloon seems better than the other solutions and is recommended by Michael.
Thanks!
Liang
> --
>
> David
next prev parent reply other threads:[~2017-01-18 13:29 UTC|newest]
Thread overview: 100+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-21 6:52 [PATCH v6 kernel 0/5] Extend virtio-balloon for fast (de)inflating & fast live migration Liang Li
2016-12-21 6:52 ` [Qemu-devel] " Liang Li
2016-12-21 6:52 ` Liang Li
2016-12-21 6:52 ` Liang Li
2016-12-21 6:52 ` [PATCH v6 kernel 1/5] virtio-balloon: rework deflate to add page to a list Liang Li
2016-12-21 6:52 ` [Qemu-devel] " Liang Li
2016-12-21 6:52 ` Liang Li
2016-12-21 6:52 ` Liang Li
2016-12-21 6:52 ` [PATCH v6 kernel 2/5] virtio-balloon: define new feature bit and head struct Liang Li
2016-12-21 6:52 ` [Qemu-devel] " Liang Li
2016-12-21 6:52 ` Liang Li
2017-01-12 19:43 ` Michael S. Tsirkin
2017-01-12 19:43 ` Michael S. Tsirkin
2017-01-12 19:43 ` [Qemu-devel] " Michael S. Tsirkin
2017-01-12 19:43 ` Michael S. Tsirkin
2017-01-13 9:24 ` [virtio-dev] " Li, Liang Z
2017-01-13 9:24 ` [Qemu-devel] " Li, Liang Z
2017-01-13 9:24 ` Li, Liang Z
2017-01-17 19:11 ` Michael S. Tsirkin
2017-01-17 19:11 ` [Qemu-devel] " Michael S. Tsirkin
2017-01-17 19:11 ` Michael S. Tsirkin
2017-01-18 1:55 ` Li, Liang Z
2017-01-18 1:55 ` Li, Liang Z
2017-01-18 1:55 ` [Qemu-devel] " Li, Liang Z
2017-01-18 1:55 ` Li, Liang Z
2017-01-18 15:30 ` Michael S. Tsirkin
2017-01-18 15:30 ` Michael S. Tsirkin
2017-01-18 15:30 ` [Qemu-devel] " Michael S. Tsirkin
2017-01-18 15:30 ` Michael S. Tsirkin
2017-01-18 15:30 ` Michael S. Tsirkin
2017-01-19 1:30 ` [virtio-dev] " Li, Liang Z
2017-01-19 1:30 ` [Qemu-devel] " Li, Liang Z
2017-01-19 1:30 ` Li, Liang Z
2017-01-19 1:30 ` Li, Liang Z
2017-01-19 1:30 ` [virtio-dev] " Li, Liang Z
2017-01-17 19:11 ` Michael S. Tsirkin
2017-01-13 9:24 ` Li, Liang Z
2016-12-21 6:52 ` Liang Li
2016-12-21 6:52 ` [PATCH v6 kernel 3/5] virtio-balloon: speed up inflate/deflate process Liang Li
2016-12-21 6:52 ` [Qemu-devel] " Liang Li
2016-12-21 6:52 ` Liang Li
2017-01-17 19:15 ` Michael S. Tsirkin
2017-01-17 19:15 ` [Qemu-devel] " Michael S. Tsirkin
2017-01-17 19:15 ` Michael S. Tsirkin
2017-01-18 4:56 ` Li, Liang Z
2017-01-18 4:56 ` Li, Liang Z
2017-01-18 4:56 ` [Qemu-devel] " Li, Liang Z
2017-01-18 4:56 ` Li, Liang Z
2017-01-18 4:56 ` Li, Liang Z
2017-01-18 15:30 ` Michael S. Tsirkin
2017-01-18 15:30 ` [Qemu-devel] " Michael S. Tsirkin
2017-01-18 15:30 ` Michael S. Tsirkin
2017-01-18 15:30 ` Michael S. Tsirkin
2017-01-19 1:44 ` Li, Liang Z
2017-01-19 1:44 ` [Qemu-devel] " Li, Liang Z
2017-01-19 1:44 ` Li, Liang Z
2017-01-19 1:44 ` Li, Liang Z
2017-01-20 16:34 ` Michael S. Tsirkin
2017-01-20 16:34 ` [Qemu-devel] " Michael S. Tsirkin
2017-01-20 16:34 ` Michael S. Tsirkin
2017-01-20 16:34 ` Michael S. Tsirkin
2017-01-17 19:15 ` Michael S. Tsirkin
2017-01-20 11:48 ` Dr. David Alan Gilbert
2017-01-20 11:48 ` [Qemu-devel] " Dr. David Alan Gilbert
2017-01-20 11:48 ` Dr. David Alan Gilbert
2017-02-04 4:35 ` Li, Liang Z
2017-02-04 4:35 ` [Qemu-devel] " Li, Liang Z
2017-02-04 4:35 ` Li, Liang Z
2017-02-04 4:35 ` Li, Liang Z
2017-01-20 11:48 ` Dr. David Alan Gilbert
2016-12-21 6:52 ` Liang Li
2016-12-21 6:52 ` [PATCH v6 kernel 4/5] virtio-balloon: define flags and head for host request vq Liang Li
2016-12-21 6:52 ` [Qemu-devel] " Liang Li
2016-12-21 6:52 ` Liang Li
2016-12-21 6:52 ` Liang Li
2016-12-21 6:52 ` [PATCH v6 kernel 5/5] virtio-balloon: tell host vm's unused page info Liang Li
2016-12-21 6:52 ` [Qemu-devel] " Liang Li
2016-12-21 6:52 ` Liang Li
2016-12-21 6:52 ` Liang Li
2017-01-10 6:43 ` [PATCH v6 kernel 0/5] Extend virtio-balloon for fast (de)inflating & fast live migration Li, Liang Z
2017-01-10 6:43 ` [Qemu-devel] " Li, Liang Z
2017-01-10 6:43 ` Li, Liang Z
2017-01-10 6:43 ` Li, Liang Z
2017-01-18 10:09 ` David Hildenbrand
2017-01-18 10:09 ` [Qemu-devel] " David Hildenbrand
2017-01-18 10:09 ` David Hildenbrand
2017-01-18 10:09 ` David Hildenbrand
2017-01-18 13:29 ` Li, Liang Z
2017-01-18 13:29 ` [Qemu-devel] " Li, Liang Z
2017-01-18 13:29 ` Li, Liang Z
2017-01-18 13:29 ` Li, Liang Z
2017-01-18 13:29 ` Li, Liang Z [this message]
2017-01-18 15:38 ` Michael S. Tsirkin
2017-01-18 15:38 ` Michael S. Tsirkin
2017-01-18 15:38 ` [Qemu-devel] " Michael S. Tsirkin
2017-01-18 15:38 ` Michael S. Tsirkin
2017-01-19 17:24 ` David Hildenbrand
2017-01-19 17:24 ` David Hildenbrand
2017-01-19 17:24 ` [Qemu-devel] " David Hildenbrand
2017-01-19 17:24 ` David Hildenbrand
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