On Mon, Aug 27, 2018 at 09:32:16AM +0800, Wei Wang wrote: > 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 host. It can be used to accelerate virtual machine (VM) live > migration. 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 have the hypervisor write-protect all the guest memory. > > This feature enables the optimization by skipping the transfer of guest > free pages during VM live migration. 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 subsequent round if they are used and written. OK so it will be in linux-next. Now can I trouble you for a virtio spec patch with the description please? > * Tests > 1 Test Environment > Host: Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz > Migration setup: migrate_set_speed 100G, migrate_set_downtime 400ms > > 2 Test Results (results are averaged over several repeated runs) > 2.1 Guest setup: 8G RAM, 4 vCPU > 2.1.1 Idle guest live migration time > Optimization v.s. Legacy = 620ms vs 2970ms > --> ~79% reduction > 2.1.2 Guest live migration with Linux compilation workload > (i.e. make bzImage -j4) running > 1) Live Migration Time: > Optimization v.s. Legacy = 2273ms v.s. 4502ms > --> ~50% reduction > 2) Linux Compilation Time: > Optimization v.s. Legacy = 8min42s v.s. 8min43s > --> no obvious difference > > 2.2 Guest setup: 128G RAM, 4 vCPU > 2.2.1 Idle guest live migration time > Optimization v.s. Legacy = 5294ms vs 41651ms > --> ~87% reduction > 2.2.2 Guest live migration with Linux compilation workload > 1) Live Migration Time: > Optimization v.s. Legacy = 8816ms v.s. 54201ms > --> 84% reduction > 2) Linux Compilation Time: > Optimization v.s. Legacy = 8min30s v.s. 8min36s > --> no obvious difference > > ChangeLog: > v36->v37: > - free the reported pages to mm when receives a DONE cmd from host. > Please see patch 1's commit log for reasons. Please see patch 1's > commit for detailed explanations. > > For ChangeLogs from v22 to v36, please reference > https://lkml.org/lkml/2018/7/20/199 > > For ChangeLogs before v21, please reference > https://lwn.net/Articles/743660/ > > Wei Wang (3): > virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT > mm/page_poison: expose page_poisoning_enabled to kernel modules > virtio-balloon: VIRTIO_BALLOON_F_PAGE_POISON > > drivers/virtio/virtio_balloon.c | 374 ++++++++++++++++++++++++++++++++---- > include/uapi/linux/virtio_balloon.h | 8 + > mm/page_poison.c | 6 + > 3 files changed, 355 insertions(+), 33 deletions(-) > > -- > 2.7.4
