Re: Question about performance comparison between virtio-fs and virtio-blk

[Vivek Goyal]

On Tue, Jul 26, 2022 at 10:41:23PM +0800, Hao Xu wrote:
> On 7/26/22 21:17, Vivek Goyal wrote:
> > On Tue, Jul 26, 2022 at 08:55:38AM -0400, Stefan Hajnoczi wrote:
> > > On Tue, 26 Jul 2022 at 08:24, Hao Xu <hao.xu@linux.dev> wrote:
> > > > I watched your presentation about virtiofs in 2020,
> > > > 
> > > > https://www.youtube.com/watch?v=EIVOzTsGMMI&t=232s
> > > > 
> > > > which is really helpful to me, but I have a question about the graph at
> > > > 3:53, could you give
> > > > 
> > > > me more info about the test, like what tool you use for the test, if
> > > > it's fio, what is the parameters.
> > > > 
> > > > I used fio to do randread test in a qemu box, but turns out the iops of
> > > > virtio-blk and virtio-fs are similar.
> > > 
> > 
> > Hi Hao,
> > 
> > My impression in general is that virtio-blk is much faster than virtiofs.
> 
> When testing virtio-blk, did you use the device directly or mount it and
> test against a file.

Frankly speaking, I don't recall any of the details right now. If do
remember that I ran some kernel compilation tests on virtio-blk and
that ofcourse needed mounting filesystem on virtio-blk.

> 
> > A simple macro test is do a kernel compilation and compare time taken
> > between the two.
> 
> Good idea, I just tested with single file.

single file using fio is good as micro benchmark which primarily
excercises the data operations. But kernel compilation is a good
macro benchmark sort of workload which stresses filesystem both for
data and metadata operations.

Thanks
Vivek

> 
> Thanks,
> Hao
> 
> > 
> > > I have CCed Vivek Goyal, who has done more virtiofs benchmarking and
> > > might have ideas to share.
> > > 
> > > The benchmarking tool was fio with the stated blocksize and I/O
> > > pattern. The benchmark was probably run with direct=1. Based on the
> > > virtio-blk numbers I think iodepth was greater than 1 but I don't have
> > > the exact fio job parameters.
> > 
> > I had basically used fio jobs. I wrote some simple wrapper scripts to
> > run fio and parse and report numbers.
> > 
> > https://github.com/rhvgoyal/virtiofs-tests
> > 
> > I don't have data for virtio-blk but I do seem to have some comparison
> > numbers of virtiofs and virtio-9p.
> > 
> > https://github.com/rhvgoyal/virtiofs-tests/tree/master/performance-results/feb-23-2021
> > 
> > Thanks
> > Vivek
> > 
> > 
>