virtio-fs looks a bit bad in performance.

[daiaji]

I use an Intel 900p 280G Optane SSD, and use the btrfs file system, the mounting parameters are as follows:
/dev/nvme0n1p2 on /home type btrfs (rw,noatime,compress=zstd:3,ssd,discard=async,space_cache=v2,subvolid=1527,subvol=/@home)
The libvirt parameters are as follows:

<filesystem type='mount' accessmode='passthrough'>    
  <driver type='virtiofs' queue='1024'/>    
  <source dir='/home/test/Vfs'/>    
  <target dir='Vfs'/>    
</filesystem>

I don't know why the performance looks so bad, the continuous read and write performance is only one-fifteenth of the bare metal.

[YanVugenfirer]

Hello All,

Please help us understanding you use cases for using virtio-fs, and thus make us virtio-fs support better.
Please participate in the discussion and add your use cases: #726

Thanks a lot,
Yan.

[daiaji]

@YanVugenfirer I noticed that this Issues was added with a feature request, does this mean that the win driver for virtio-fs just started performance optimization some time ago?

[YanVugenfirer]

Hi @daiaji, virtio-fs driver is relatively new driver in virtio-win drivers collection. And currently we view it as tech preview. That means we expect some issues, definitely those related to performance.

[wangyan0507]

I also meet the performance problem，virtiofs has a bad performance compared with samba in guest windows.
Compared with guest linux, its continuous read and write performance is only one-third.

[viktor-prutyanov]

Hi @wangyan0507

How do you measure the performance?

[wangyan0507]

Hi @viktor-prutyanov

[Compared with linux guest]
virtiofsd:
./virtiofsd --socket-path=/tmp/vhostqemu -o source=$TESTDIR -o cache=always
qemu-6.2:
./build/qemu-system-aarch64
-chardev socket,id=char0,path=/tmp/vhostqemu
-device vhost-user-fs-pci,queue-size=1024,chardev=char0,tag=myfs
-m 4G -object memory-backend-memfd,id=mem1,size=4G,share=on -numa node,memdev=mem1
-machine virt,virtualization=off,its=off,gic-version=host
-accel kvm
-cpu host -smp 4
-bios ./QEMU_EFI.fd
-object iothread,id=disk-iothread
-device virtio-blk-pci,drive=win11,iothread=disk-iothread
-drive if=none,id=win11,format=qcow2,file=./win11.qcow2,overlap-check=none,cache=unsafe
fio:
win11 guest: fio -name=test -filename=./test -direct=1 -iodepth=8 -rw=read/write -ioengine=windowsaio -bs=1M -size=4g -group_reporting --time_based -runtime=20
ubuntu22.04 guest:fio -name=test -filename=./test -direct=1 -iodepth=8 -rw=read/write -ioengine=libaio -bs=1M -size=4g -group_reporting --time_based -runtime=20

test read(bs-1M) write(bs-1M)
win11 281MB/s 300MB/s
ubuntu2204 1078MB/s 1262MB/s

[viktor-prutyanov]

@wangyan0507

So, you're running VirtIO-FS on ARM64 ?

[wangyan0507]

@viktor-prutyanov
Yes, the host is arm64 os.

The samba performace is using win11/ubuntu2204 guest:
test read(bs-1M) write(bs-1M)
win11 996MB/s 896MB/s
ubuntu2204 935MB/s 889MB/s

It's better than virtiofs on win11, worse than virtiofs on ubuntu2204