Re: [Qemu-devel] [PATCH v2 00/15] SCSI s/g + SCSI migration + virtio-scsi

[Paolo Bonzini]

On 02/09/2012 06:46 AM, Hu Tao wrote:
> > > >  >I've re-tested today, with host kernel 2.6.35.6-45.fc14.x86_64,
> > > >  >2.6.32-71.el6.x86_64, 3.1.0 and 3.3.0-rc1+, qemu version and guest
> > > >  >configuration remain the same, including guest kernel. It apears
> > > >  >that the problem appears only when the host kernel version is 3.1.0.
> Sorry, forget about the kernel versions. With very heavy IO load, it's
> easy to reproduce the problem. In my case, 300 disks were attached to a
> virtio-scsi HBA, and 300 dd processes were launched at the same time,
> each for a disk.

Yes, we're not yet optimizing for _that_ kind of scalability. :)  That 
raw works is already surprising enough to me!

What disk was it?  Can you try on an SSD?

Paolo