Re: [RFC PATCH]vhost-blk: In-kernel accelerator for virtio blockdevice

[Badari Pulavarty]

On 8/7/2011 6:35 PM, Liu Yuan wrote:
> On 08/06/2011 02:02 AM, Badari Pulavarty wrote:
> > On 8/5/2011 4:04 AM, Liu Yuan wrote:
> > > On 08/05/2011 05:58 AM, Badari Pulavarty wrote:
> > > > Hi Liu Yuan,
> > > >
> > > > I started testing your patches. I applied your kernel patch to 3.0
> > > > and applied QEMU to latest git.
> > > >
> > > > I passed 6 blockdevices from the host to guest (4 vcpu, 4GB RAM).
> > > > I ran simple "dd" read tests from the guest on all block devices
> > > > (with various blocksizes, iflag=direct).
> > > >
> > > > Unfortunately, system doesn't stay up. I immediately get into
> > > > panic on the host. I didn't get time to debug the problem. Wondering
> > > > if you have seen this issue before and/or you have new patchset
> > > > to try ?
> > > >
> > > > Let me know.
> > > >
> > > > Thanks,
> > > > Badari
> > >
> > > Okay, it is actually a bug pointed out by MST on the other thread, 
> > > that it needs a mutex for completion thread.
> > >
> > > Now would you please this attachment?This patch only applies to 
> > > kernel part, on top of v1 kernel patch.
> > >
> > > This patch mainly moves completion thread into vhost thread as a 
> > > function. As a result, both requests submitting and completion 
> > > signalling is in the same thread.
> > >
> > > Yuan
> >
> > Unfortunately, "dd" tests (4 out of 6) in the guest hung. I see 
> > following messages
> >
> > virtio_blk virtio2: requests: id 0 is not a head !
> > virtio_blk virtio3: requests: id 1 is not a head !
> > virtio_blk virtio5: requests: id 1 is not a head !
> > virtio_blk virtio1: requests: id 1 is not a head !
> >
> > I still see host panics. I will collect the host panic and see if its 
> > still same or not.
> >
> > Thanks,
> > Badari
> Would you please show me how to reproduce it step by step? I tried dd 
> with two block device attached, but didn't get hung nor panic.
>
> Yuan

I did 6 "dd"s on 6 block devices..

dd if=/dev/vdb of=/dev/null bs=1M iflag=direct &
dd if=/dev/vdc of=/dev/null bs=1M iflag=direct &
dd if=/dev/vdd of=/dev/null bs=1M iflag=direct &
dd if=/dev/vde of=/dev/null bs=1M iflag=direct &
dd if=/dev/vdf of=/dev/null bs=1M iflag=direct &
dd if=/dev/vdg of=/dev/null bs=1M iflag=direct &

I can reproduce the problem with in 3 minutes :(

Thanks,
Badari


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