[libvirt] NFS over RDMA small block DIRECT_IO bug

[Andrew Holway]

Hi Steve,

Do you think these patches will make their way into the redhat kernel sometime soon?

What is the state of support for NFS over RDMA support at redhat?

Thanks,

Andrew


On Sep 11, 2012, at 7:03 PM, Steve Dickson wrote:

> 
> 
> On 09/04/2012 05:31 AM, Andrew Holway wrote:
>> Hello.
>> 
>> # Avi Kivity avi(a)redhat recommended I copy kvm in on this. It would also seem relevent to libvirt. #
>> 
>> I have a Centos 6.2 server and Centos 6.2 client.
>> 
>> [root at store ~]# cat /etc/exports 
>> /dev/shm				10.149.0.0/16(rw,fsid=1,no_root_squash,insecure)    (I have tried with non tempfs targets also)
>> 
>> 
>> [root at node001 ~]# cat /etc/fstab 
>> store.ibnet:/dev/shm             /mnt                 nfs          rdma,port=2050,defaults 0 0
>> 
>> 
>> I wrote a little for loop one liner that dd'd the centos net install image to a file called 'hello' then checksummed that file. Each iteration uses a different block size.
>> 
>> Non DIRECT_IO seems to work fine. DIRECT_IO with 512byte, 1K and 2K block sizes get corrupted.
>> 
>> I want to run my KVM guests on top of NFS over RDMA. My guests cannot create filesystems.
>> 
>> Thanks,
>> 
>> Andrew.
>> 
>> bug report: https://bugzilla.linux-nfs.org/show_bug.cgi?id=228
> Well it appears the RHEL6 kernels are lacking a couple patches that might
> help with this....
> 
> 5c635e09 RPCRDMA: Fix FRMR registration/invalidate handling.
> 9b78145c xprtrdma: Remove assumption that each segment is <= PAGE_SIZE
> 
> I can only image that Centos 6.2 might me lacking these too... ;-)
> 
> steved.
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