On Thu, Jul 16, 2020 at 10:41:50AM +0800, Hui Zhu wrote: > The first, second and third version are in [1], [2] and [3]. > Code of current version for Linux and qemu is available in [4] and [5]. > Update of this version: > 1. Report continuous pages will increase the speed. So added deflate > continuous pages. > 2. According to the comments from David in [6], added 2 new vqs inflate_cont_vq > and deflate_cont_vq to report continuous pages with format 32 bits pfn and 32 > bits size. > Following is the introduction of the function. > These patches add VIRTIO_BALLOON_F_CONT_PAGES to virtio_balloon. With this > flag, balloon tries to use continuous pages to inflate and deflate. > Opening this flag can bring two benefits: > 1. Report continuous pages will increase memory report size of each time > call tell_host. Then it will increase the speed of balloon inflate and > deflate. > 2. Host THPs will be splitted when qemu release the page of balloon inflate. > Inflate balloon with continuous pages will let QEMU release the pages > of same THPs. That will help decrease the splitted THPs number in > the host. > Following is an example in a VM with 1G memory 1CPU. This test setups an > environment that has a lot of fragmentation pages. Then inflate balloon will > split the THPs. > // This is the THP number before VM execution in the host. > // None use THP. > cat /proc/meminfo | grep AnonHugePages: > AnonHugePages: 0 kB > // After VM start, use usemem > // (https://git.kernel.org/pub/scm/linux/kernel/git/wfg/vm-scalability.git) > // punch-holes function generates 400m fragmentation pages in the guest > // kernel. > usemem --punch-holes -s -1 800m & > // This is the THP number after this command in the host. > // Some THP is used by VM because usemem will access 800M memory > // in the guest. > cat /proc/meminfo | grep AnonHugePages: > AnonHugePages: 911360 kB > // Connect to the QEMU monitor, setup balloon, and set it size to 600M. > (qemu) device_add virtio-balloon-pci,id=balloon1 > (qemu) info balloon > balloon: actual=1024 > (qemu) balloon 600 > (qemu) info balloon > balloon: actual=600 > // This is the THP number after inflate the balloon in the host. > cat /proc/meminfo | grep AnonHugePages: > AnonHugePages: 88064 kB > // Set the size back to 1024M in the QEMU monitor. > (qemu) balloon 1024 > (qemu) info balloon > balloon: actual=1024 > // Use usemem to increase the memory usage of QEMU. > killall usemem > usemem 800m > // This is the THP number after this operation. > cat /proc/meminfo | grep AnonHugePages: > AnonHugePages: 65536 kB > > Following example change to use continuous pages balloon. The number of > splitted THPs is decreased. > // This is the THP number before VM execution in the host. > // None use THP. > cat /proc/meminfo | grep AnonHugePages: > AnonHugePages: 0 kB > // After VM start, use usemem punch-holes function generates 400M > // fragmentation pages in the guest kernel. > usemem --punch-holes -s -1 800m & > // This is the THP number after this command in the host. > // Some THP is used by VM because usemem will access 800M memory > // in the guest. > cat /proc/meminfo | grep AnonHugePages: > AnonHugePages: 911360 kB > // Connect to the QEMU monitor, setup balloon, and set it size to 600M. > (qemu) device_add virtio-balloon-pci,id=balloon1,cont-pages=on > (qemu) info balloon > balloon: actual=1024 > (qemu) balloon 600 > (qemu) info balloon > balloon: actual=600 > // This is the THP number after inflate the balloon in the host. > cat /proc/meminfo | grep AnonHugePages: > AnonHugePages: 616448 kB > // Set the size back to 1024M in the QEMU monitor. > (qemu) balloon 1024 > (qemu) info balloon > balloon: actual=1024 > // Use usemem to increase the memory usage of QEMU. > killall usemem > usemem 800m > // This is the THP number after this operation. > cat /proc/meminfo | grep AnonHugePages: > AnonHugePages: 907264 kB I'm a bit confused about which of the above run within guest, and which run within host. Could you explain pls? > [1] https://lkml.org/lkml/2020/3/12/144 > [2] https://lore.kernel.org/linux-mm/1584893097-12317-1-git-send-email-teawater@xxxxxxxxx/ > [3] https://lkml.org/lkml/2020/5/12/324 > [4] https://github.com/teawater/linux/tree/balloon_conts > [5] https://github.com/teawater/qemu/tree/balloon_conts > [6] https://lkml.org/lkml/2020/5/13/1211 > > Hui Zhu (2): > virtio_balloon: Add VIRTIO_BALLOON_F_CONT_PAGES and inflate_cont_vq > virtio_balloon: Add deflate_cont_vq to deflate continuous pages > > drivers/virtio/virtio_balloon.c | 180 +++++++++++++++++++++++++++++++----- > include/linux/balloon_compaction.h | 12 ++ > include/uapi/linux/virtio_balloon.h | 1 > mm/balloon_compaction.c | 117 +++++++++++++++++++++-- > 4 files changed, 280 insertions(+), 30 deletions(-)
