Re: [PATCH 0/1] vhost: add vhost_blk driver

[Jason Wang]

On 2018/11/5 äå11:23, Vitaly Mayatskih wrote:
> On Sun, Nov 4, 2018 at 10:00 PM Jason Wang <jasowang@xxxxxxxxxx> wrote:
>
> > > # fio num-jobs
> > > # A: bare metal over block
> > > # B: bare metal over file
> > > # C: virtio-blk over block
> > > # D: virtio-blk over file
> > > # E: vhost-blk bio over block
> > > # F: vhost-blk kiocb over block
> > > # G: vhost-blk kiocb over file
> > > #
> > > #  A     B     C    D    E     F     G
> > > 16 1480k 1506k 101k 102k 1346k 1202k 566k
> > Hi:
> >
> > Thanks for the patches.
> >
> > This is not the first attempt for having vhost-blk:
> >
> > - Badari's version: https://lwn.net/Articles/379864/
> >
> > - Asias' version: https://lwn.net/Articles/519880/
> >
> > It's better to describe the differences (kiocb vs bio? performance?).
> > E.g if my memory is correct, Asias said it doesn't give much improvement
> > compared with userspace qemu.
> >
> > And what's more important, I believe we tend to use virtio-scsi nowdays.
> > So what's the advantages of vhost-blk over vhost-scsi?
> Hi,
>
> Yes, I saw both. Frankly, my implementation is not that different,
> because the whole thing has only twice more LOC that vhost/test.c.
>
> I posted my numbers (see in quoted text above the 16 queues case),
> IOPS goes from ~100k to 1.2M and almost reaches the physical
> limitation of the backend.
>
> submit_bio() is a bit faster, but can't be used for disk images placed
> on a file system. I have that submit_bio implementation too.
>
> Storage industry is shifting away from SCSI, which has a scaling
> problem.


Know little about storage. For scaling, do you mean SCSI protocol 
itself? If not, it's probably not a real issue for virtio-scsi itself.


>   I can compare vhost-scsi vs vhost-blk if you are curious.


It would be very helpful to see the performance comparison.


Thanks


> Thanks!