linux-kernel - Re: [RFC PATCH]vhost-blk: In-kernel accelerator for virtio block device

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Date:	Mon, 08 Aug 2011 09:35:10 +0800
From:	Liu Yuan <namei.unix@...il.com>
To:	Badari Pulavarty <pbadari@...ibm.com>
CC:	Stefan Hajnoczi <stefanha@...il.com>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Avi Kivity <avi@...hat.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, Khoa Huynh <khoa@...ibm.com>
Subject: Re: [RFC PATCH]vhost-blk: In-kernel accelerator for virtio block
 device

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
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