Re: [Xen-devel] xen-blkfront hang

[Dongli Zhang <dongli.zhang@xxxxxxxxxx>]

Here are the options:

1. Dump a vmcore of guest and print nr_grant_frames with crash utility.

2. Implement a kernel module in guest to dump nr_grant_frames if you still have
access to your hung guest domU.

3. There is a new utility in xen toolstack at tools/misc/xen-diag.c to dump
grant table usage for arbitrary guest domU (including dom0)

./xen-diag gnttab_query_size [domid]

4. If your host's xen toolstack does not have xen-diag, feel free to implement
one your self via GNTTABOP_query_size hypercall and compile with -lxenctrl.

Dongli Zhang


On 07/31/2017 02:30 PM, Valentin Vidic wrote:
> On Mon, Jul 31, 2017 at 09:09:19AM +0800, Dongli Zhang wrote:
>> This patch is not able to fix the lack of grant issue permanently. It is 
>> used to
>> optimize the utilization of grant table entires.
>>
>> To verify whether the above patch would help, please check the 
>> nr_grant_frames
>> value in guest domU. If this value is exactly the same of maximum grant 
>> frames
>> (by default, xen mainline uses 32) and the number of free grant references is
>> very small, the above patch might help.
> 
> I can try that, but how do I get the nr_grant_frames value in domU?
> 

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