From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [RFC for Linux v4 0/2] virtio_balloon: Add VIRTIO_BALLOON_F_CONT_PAGES to report continuous pages Date: Thu, 16 Jul 2020 06:45:00 -0400 Message-ID: <20200716064340-mutt-send-email-mst@kernel.org> References: <1594867315-8626-1-git-send-email-teawater@gmail.com> <20200716021929-mutt-send-email-mst@kernel.org> <744230FA-78D8-4568-8188-683087065E84@linux.alibaba.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: In-Reply-To: <744230FA-78D8-4568-8188-683087065E84@linux.alibaba.com> Content-Disposition: inline To: teawater Cc: Hui Zhu , david@redhat.com, jasowang@redhat.com, akpm@linux-foundation.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, qemu-devel@nongnu.org, virtio-dev@lists.oasis-open.org, Andrea Arcangeli List-Id: virtualization@lists.linuxfoundation.org On Thu, Jul 16, 2020 at 03:01:18PM +0800, teawater wrote: > > > > 2020年7月16日 14:38，Michael S. Tsirkin 写道： > > > > 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 > These lines are from host. > > >> // 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 & > These lines are from guest. They setups the environment that has a lot of fragmentation pages. > > >> // 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 > These lines are from host. > > >> // 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 > These lines are from host. > > >> // This is the THP number after inflate the balloon in the host. > >> cat /proc/meminfo | grep AnonHugePages: > >> AnonHugePages: 88064 kB > These lines are from host. > > >> // Set the size back to 1024M in the QEMU monitor. > >> (qemu) balloon 1024 > >> (qemu) info balloon > >> balloon: actual=1024 > These lines are from host. > > >> // Use usemem to increase the memory usage of QEMU. > >> killall usemem > >> usemem 800m > These lines are from guest. > > >> // This is the THP number after this operation. > >> cat /proc/meminfo | grep AnonHugePages: > >> AnonHugePages: 65536 kB > These lines are from host. > > > > >> > >> 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 > These lines are from host. > > >> // After VM start, use usemem punch-holes function generates 400M > >> // fragmentation pages in the guest kernel. > >> usemem --punch-holes -s -1 800m & > These lines are from guest. They setups the environment that has a lot of fragmentation pages. > > >> // 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 > These lines are from host. > > >> // 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 > These lines are from host. > > >> // 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 > These lines are from host. > > >> // Use usemem to increase the memory usage of QEMU. > >> killall usemem > >> usemem 800m > These lines are from guest. > > >> // This is the THP number after this operation. > >> cat /proc/meminfo | grep AnonHugePages: > >> AnonHugePages: 907264 kB > These lines are from host. > > > > > I'm a bit confused about which of the above run within guest, > > and which run within host. Could you explain pls? > > > > > > I added some introduction to show where these lines is get from. > > Best, > Hui OK so we see host has more free THPs. But guest has presumably less now - so the total page table depth is the same. Did we gain anything? > > > > >> [1] https://lkml.org/lkml/2020/3/12/144 > >> [2] https://lore.kernel.org/linux-mm/1584893097-12317-1-git-send-email-teawater@gmail.com/ > >> [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(-) > > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org > > For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org