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

From: Liu Yuan
Date: Sun Aug 07 2011 - 21:35:33 EST


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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