Messages in this thread | | | Date | Fri, 02 Feb 2018 20:48:39 +0800 | From | Wei Wang <> | Subject | Re: [PATCH v25 0/2] Virtio-balloon: support free page reporting |
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On 02/02/2018 03:15 AM, Michael S. Tsirkin wrote: > On Thu, Jan 25, 2018 at 05:14:04PM +0800, Wei Wang wrote: >> This patch series is separated from the previous "Virtio-balloon >> Enhancement" series. The new feature, VIRTIO_BALLOON_F_FREE_PAGE_HINT, >> implemented by this series enables the virtio-balloon driver to report >> hints of guest free pages to the host. It can be used to accelerate live >> migration of VMs. Here is an introduction of this usage: >> >> 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. > Could you post performance numbers please?
Yes, it was posted here https://lkml.org/lkml/2018/1/25/698
I just changed the host side to poll the vq so that we don't need kick in the driver, it works pretty well. I'll test a little bit more and post out a new version with new performance numbers attached in the cover letter.
Best, Wei
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