> Alexandre Derumier via pve-devel <pve-devel@lists.proxmox.com> hat am > 19.05.2025 12:23 CEST geschrieben: > This is part of my work on qcow2 external snapshot, but could improve current > qcow2 linked clone > > This patch serie move qemu_img_create to common helpers, > and enable preallocation on backed_image to increase performance
did you maybe forget to send the actual patches? I can't find them in my inbox, and they aren't on lore either: https://lore.proxmox.com/pve-devel/mailman.556.1747917864.394.pve-de...@lists.proxmox.com/t/#u > > This require l2_extended=on on the backed image > > I have done some benchmarks on localssd with 100gb qcow2, the performance in > randwrite 4k is 5x faster > > some presentation of l2_extended=on are available here > https://www.youtube.com/watch?v=zJetcfDVFNw > https://www.youtube.com/watch?v=NfgLCdtkRus > > I don't have enabled it for base image, as I think that Fabian see > performance regression some month ago. > but I don't see performance difference in my bench. (can you could test on > your side again ?) > > It could help to reduce qcow2 overhead on disk, > and allow to keep more metadatas in memory for bigger image, as qemu default > memory l2_cache_size=1MB) > https://www.ibm.com/products/tutorials/how-to-tune-qemu-l2-cache-size-and-qcow2-cluster-size > Maybe more test with bigger image (>1TB) could be done too to see if it's help > > > > bench on 100G qcow2 file: > > fio --filename=/dev/sdb --direct=1 --rw=randwrite --bs=4k --iodepth=32 > --ioengine=libaio --name=test > fio --filename=/dev/sdb --direct=1 --rw=randread --bs=4k --iodepth=32 > --ioengine=libaio --name=test > > base image: > > randwrite 4k: prealloc=metadata, l2_extended=off, cluster_size=64k: 20215 > randread 4k: prealloc=metadata, l2_extended=off, cluster_size=64k: 22219 > randwrite 4k: prealloc=metadata, l2_extended=on, cluster_size=64k: 20217 > randread 4k: prealloc=metadata, l2_extended=on, cluster_size=64k: 21742 > randwrite 4k: prealloc=metadata, l2_extended=on, cluster_size=128k: 21599 > randread 4k: prealloc=metadata, l2_extended=on, cluster_size=128k: 22037 > > linked clone image with backing file: > > randwrite 4k: prealloc=metadata, l2_extended=off, cluster_size=64k: 3912 > randread 4k: prealloc=metadata, l2_extended=off, cluster_size=64k: 21476 > randwrite 4k: prealloc=metadata, l2_extended=on, cluster_size=64k: 20563 > randread 4k: prealloc=metadata, l2_extended=on, cluster_size=64k: 22265 > randwrite 4k: prealloc=metadata, l2_extended=on, cluster_size=128k: 18016 > randread 4k: prealloc=metadata, l2_extended=on, cluster_size=128k: 21611 > > Alexandre Derumier (2): > common: add qemu_img_create an preallocation_cmd_option > common: qemu_img_create: add backing_file support > > src/PVE/Storage/Common.pm | 62 ++++++++++++++++++++++++++++++ > src/PVE/Storage/GlusterfsPlugin.pm | 2 +- > src/PVE/Storage/Plugin.pm | 52 +------------------------ > 3 files changed, 65 insertions(+), 51 deletions(-) > > -- > 2.39.5 _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
